This patch series adjusts functions in the get_user_pages* family such that desired FOLL_* flags are passed as an argument rather than implied by flags.
The purpose of this change is to make the use of FOLL_FORCE explicit so it is easier to grep for and clearer to callers that this flag is being used. The use of FOLL_FORCE is an issue as it overrides missing VM_READ/VM_WRITE flags for the VMA whose pages we are reading from/writing to, which can result in surprising behaviour.
The patch series came out of the discussion around commit 38e0885, which addressed a BUG_ON() being triggered when a page was faulted in with PROT_NONE set but having been overridden by FOLL_FORCE. do_numa_page() was run on the assumption the page _must_ be one marked for NUMA node migration as an actual PROT_NONE page would have been dealt with prior to this code path, however FOLL_FORCE introduced a situation where this assumption did not hold.
See https://marc.info/?l=linux-mm&m=147585445805166 for the patch proposal.
Lorenzo Stoakes (10): mm: remove write/force parameters from __get_user_pages_locked() mm: remove write/force parameters from __get_user_pages_unlocked() mm: replace get_user_pages_unlocked() write/force parameters with gup_flags mm: replace get_user_pages_locked() write/force parameters with gup_flags mm: replace get_vaddr_frames() write/force parameters with gup_flags mm: replace get_user_pages() write/force parameters with gup_flags mm: replace get_user_pages_remote() write/force parameters with gup_flags mm: replace __access_remote_vm() write parameter with gup_flags mm: replace access_remote_vm() write parameter with gup_flags mm: replace access_process_vm() write parameter with gup_flags
arch/alpha/kernel/ptrace.c | 9 ++-- arch/blackfin/kernel/ptrace.c | 5 ++- arch/cris/arch-v32/drivers/cryptocop.c | 4 +- arch/cris/arch-v32/kernel/ptrace.c | 4 +- arch/ia64/kernel/err_inject.c | 2 +- arch/ia64/kernel/ptrace.c | 14 +++--- arch/m32r/kernel/ptrace.c | 15 ++++--- arch/mips/kernel/ptrace32.c | 5 ++- arch/mips/mm/gup.c | 2 +- arch/powerpc/kernel/ptrace32.c | 5 ++- arch/s390/mm/gup.c | 3 +- arch/score/kernel/ptrace.c | 10 +++-- arch/sh/mm/gup.c | 3 +- arch/sparc/kernel/ptrace_64.c | 24 +++++++---- arch/sparc/mm/gup.c | 3 +- arch/x86/kernel/step.c | 3 +- arch/x86/mm/gup.c | 2 +- arch/x86/mm/mpx.c | 5 +-- arch/x86/um/ptrace_32.c | 3 +- arch/x86/um/ptrace_64.c | 3 +- drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 7 ++- drivers/gpu/drm/etnaviv/etnaviv_gem.c | 7 ++- drivers/gpu/drm/exynos/exynos_drm_g2d.c | 3 +- drivers/gpu/drm/i915/i915_gem_userptr.c | 6 ++- drivers/gpu/drm/radeon/radeon_ttm.c | 3 +- drivers/gpu/drm/via/via_dmablit.c | 4 +- drivers/infiniband/core/umem.c | 6 ++- drivers/infiniband/core/umem_odp.c | 7 ++- drivers/infiniband/hw/mthca/mthca_memfree.c | 2 +- drivers/infiniband/hw/qib/qib_user_pages.c | 3 +- drivers/infiniband/hw/usnic/usnic_uiom.c | 5 ++- drivers/media/pci/ivtv/ivtv-udma.c | 4 +- drivers/media/pci/ivtv/ivtv-yuv.c | 5 ++- drivers/media/platform/omap/omap_vout.c | 2 +- drivers/media/v4l2-core/videobuf-dma-sg.c | 7 ++- drivers/media/v4l2-core/videobuf2-memops.c | 6 ++- drivers/misc/mic/scif/scif_rma.c | 3 +- drivers/misc/sgi-gru/grufault.c | 2 +- drivers/platform/goldfish/goldfish_pipe.c | 3 +- drivers/rapidio/devices/rio_mport_cdev.c | 3 +- drivers/scsi/st.c | 5 +-- .../interface/vchiq_arm/vchiq_2835_arm.c | 3 +- .../vc04_services/interface/vchiq_arm/vchiq_arm.c | 3 +- drivers/video/fbdev/pvr2fb.c | 4 +- drivers/virt/fsl_hypervisor.c | 4 +- fs/exec.c | 9 +++- fs/proc/base.c | 19 +++++--- include/linux/mm.h | 18 ++++---- kernel/events/uprobes.c | 6 ++- kernel/ptrace.c | 16 ++++--- mm/frame_vector.c | 9 ++-- mm/gup.c | 50 ++++++++++------------ mm/memory.c | 16 ++++--- mm/mempolicy.c | 2 +- mm/nommu.c | 38 +++++++--------- mm/process_vm_access.c | 7 ++- mm/util.c | 8 ++-- net/ceph/pagevec.c | 2 +- security/tomoyo/domain.c | 2 +- virt/kvm/async_pf.c | 3 +- virt/kvm/kvm_main.c | 11 +++-- 61 files changed, 260 insertions(+), 187 deletions(-)
This patch removes the write and force parameters from __get_user_pages_locked() to make the use of FOLL_FORCE explicit in callers as use of this flag can result in surprising behaviour (and hence bugs) within the mm subsystem.
Signed-off-by: Lorenzo Stoakes lstoakes@gmail.com --- mm/gup.c | 47 +++++++++++++++++++++++++++++++++-------------- 1 file changed, 33 insertions(+), 14 deletions(-)
diff --git a/mm/gup.c b/mm/gup.c index 96b2b2f..ba83942 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -729,7 +729,6 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk, struct mm_struct *mm, unsigned long start, unsigned long nr_pages, - int write, int force, struct page **pages, struct vm_area_struct **vmas, int *locked, bool notify_drop, @@ -747,10 +746,6 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
if (pages) flags |= FOLL_GET; - if (write) - flags |= FOLL_WRITE; - if (force) - flags |= FOLL_FORCE;
pages_done = 0; lock_dropped = false; @@ -846,9 +841,15 @@ long get_user_pages_locked(unsigned long start, unsigned long nr_pages, int write, int force, struct page **pages, int *locked) { + unsigned int flags = FOLL_TOUCH; + + if (write) + flags |= FOLL_WRITE; + if (force) + flags |= FOLL_FORCE; + return __get_user_pages_locked(current, current->mm, start, nr_pages, - write, force, pages, NULL, locked, true, - FOLL_TOUCH); + pages, NULL, locked, true, flags); } EXPORT_SYMBOL(get_user_pages_locked);
@@ -869,9 +870,15 @@ __always_inline long __get_user_pages_unlocked(struct task_struct *tsk, struct m { long ret; int locked = 1; + + if (write) + gup_flags |= FOLL_WRITE; + if (force) + gup_flags |= FOLL_FORCE; + down_read(&mm->mmap_sem); - ret = __get_user_pages_locked(tsk, mm, start, nr_pages, write, force, - pages, NULL, &locked, false, gup_flags); + ret = __get_user_pages_locked(tsk, mm, start, nr_pages, pages, NULL, + &locked, false, gup_flags); if (locked) up_read(&mm->mmap_sem); return ret; @@ -963,9 +970,15 @@ long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm, int write, int force, struct page **pages, struct vm_area_struct **vmas) { - return __get_user_pages_locked(tsk, mm, start, nr_pages, write, force, - pages, vmas, NULL, false, - FOLL_TOUCH | FOLL_REMOTE); + unsigned int flags = FOLL_TOUCH | FOLL_REMOTE; + + if (write) + flags |= FOLL_WRITE; + if (force) + flags |= FOLL_FORCE; + + return __get_user_pages_locked(tsk, mm, start, nr_pages, pages, vmas, + NULL, false, flags); } EXPORT_SYMBOL(get_user_pages_remote);
@@ -979,9 +992,15 @@ long get_user_pages(unsigned long start, unsigned long nr_pages, int write, int force, struct page **pages, struct vm_area_struct **vmas) { + unsigned int flags = FOLL_TOUCH; + + if (write) + flags |= FOLL_WRITE; + if (force) + flags |= FOLL_FORCE; + return __get_user_pages_locked(current, current->mm, start, nr_pages, - write, force, pages, vmas, NULL, false, - FOLL_TOUCH); + pages, vmas, NULL, false, flags); } EXPORT_SYMBOL(get_user_pages);
On Thu 13-10-16 01:20:11, Lorenzo Stoakes wrote:
This patch removes the write and force parameters from __get_user_pages_locked() to make the use of FOLL_FORCE explicit in callers as use of this flag can result in surprising behaviour (and hence bugs) within the mm subsystem.
Signed-off-by: Lorenzo Stoakes lstoakes@gmail.com
Looks good. You can add:
Reviewed-by: Jan Kara jack@suse.cz
Honza
This patch removes the write and force parameters from __get_user_pages_unlocked() to make the use of FOLL_FORCE explicit in callers as use of this flag can result in surprising behaviour (and hence bugs) within the mm subsystem.
Signed-off-by: Lorenzo Stoakes lstoakes@gmail.com --- include/linux/mm.h | 3 +-- mm/gup.c | 17 +++++++++-------- mm/nommu.c | 12 +++++++++--- mm/process_vm_access.c | 7 +++++-- virt/kvm/async_pf.c | 3 ++- virt/kvm/kvm_main.c | 11 ++++++++--- 6 files changed, 34 insertions(+), 19 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h index e9caec6..2db98b6 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1285,8 +1285,7 @@ long get_user_pages_locked(unsigned long start, unsigned long nr_pages, int write, int force, struct page **pages, int *locked); long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm, unsigned long start, unsigned long nr_pages, - int write, int force, struct page **pages, - unsigned int gup_flags); + struct page **pages, unsigned int gup_flags); long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages, int write, int force, struct page **pages); int get_user_pages_fast(unsigned long start, int nr_pages, int write, diff --git a/mm/gup.c b/mm/gup.c index ba83942..3d620dd 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -865,17 +865,11 @@ EXPORT_SYMBOL(get_user_pages_locked); */ __always_inline long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm, unsigned long start, unsigned long nr_pages, - int write, int force, struct page **pages, - unsigned int gup_flags) + struct page **pages, unsigned int gup_flags) { long ret; int locked = 1;
- if (write) - gup_flags |= FOLL_WRITE; - if (force) - gup_flags |= FOLL_FORCE; - down_read(&mm->mmap_sem); ret = __get_user_pages_locked(tsk, mm, start, nr_pages, pages, NULL, &locked, false, gup_flags); @@ -905,8 +899,15 @@ EXPORT_SYMBOL(__get_user_pages_unlocked); long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages, int write, int force, struct page **pages) { + unsigned int flags = FOLL_TOUCH; + + if (write) + flags |= FOLL_WRITE; + if (force) + flags |= FOLL_FORCE; + return __get_user_pages_unlocked(current, current->mm, start, nr_pages, - write, force, pages, FOLL_TOUCH); + pages, flags); } EXPORT_SYMBOL(get_user_pages_unlocked);
diff --git a/mm/nommu.c b/mm/nommu.c index 95daf81..925dcc1 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -185,8 +185,7 @@ EXPORT_SYMBOL(get_user_pages_locked);
long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm, unsigned long start, unsigned long nr_pages, - int write, int force, struct page **pages, - unsigned int gup_flags) + struct page **pages, unsigned int gup_flags) { long ret; down_read(&mm->mmap_sem); @@ -200,8 +199,15 @@ EXPORT_SYMBOL(__get_user_pages_unlocked); long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages, int write, int force, struct page **pages) { + unsigned int flags = 0; + + if (write) + flags |= FOLL_WRITE; + if (force) + flags |= FOLL_FORCE; + return __get_user_pages_unlocked(current, current->mm, start, nr_pages, - write, force, pages, 0); + pages, flags); } EXPORT_SYMBOL(get_user_pages_unlocked);
diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c index 07514d4..be8dc8d 100644 --- a/mm/process_vm_access.c +++ b/mm/process_vm_access.c @@ -88,12 +88,16 @@ static int process_vm_rw_single_vec(unsigned long addr, ssize_t rc = 0; unsigned long max_pages_per_loop = PVM_MAX_KMALLOC_PAGES / sizeof(struct pages *); + unsigned int flags = FOLL_REMOTE;
/* Work out address and page range required */ if (len == 0) return 0; nr_pages = (addr + len - 1) / PAGE_SIZE - addr / PAGE_SIZE + 1;
+ if (vm_write) + flags |= FOLL_WRITE; + while (!rc && nr_pages && iov_iter_count(iter)) { int pages = min(nr_pages, max_pages_per_loop); size_t bytes; @@ -104,8 +108,7 @@ static int process_vm_rw_single_vec(unsigned long addr, * current/current->mm */ pages = __get_user_pages_unlocked(task, mm, pa, pages, - vm_write, 0, process_pages, - FOLL_REMOTE); + process_pages, flags); if (pages <= 0) return -EFAULT;
diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c index db96688..8035cc1 100644 --- a/virt/kvm/async_pf.c +++ b/virt/kvm/async_pf.c @@ -84,7 +84,8 @@ static void async_pf_execute(struct work_struct *work) * mm and might be done in another context, so we must * use FOLL_REMOTE. */ - __get_user_pages_unlocked(NULL, mm, addr, 1, 1, 0, NULL, FOLL_REMOTE); + __get_user_pages_unlocked(NULL, mm, addr, 1, NULL, + FOLL_WRITE | FOLL_REMOTE);
kvm_async_page_present_sync(vcpu, apf);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 81dfc73..28510e7 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1416,10 +1416,15 @@ static int hva_to_pfn_slow(unsigned long addr, bool *async, bool write_fault, down_read(¤t->mm->mmap_sem); npages = get_user_page_nowait(addr, write_fault, page); up_read(¤t->mm->mmap_sem); - } else + } else { + unsigned int flags = FOLL_TOUCH | FOLL_HWPOISON; + + if (write_fault) + flags |= FOLL_WRITE; + npages = __get_user_pages_unlocked(current, current->mm, addr, 1, - write_fault, 0, page, - FOLL_TOUCH|FOLL_HWPOISON); + page, flags); + } if (npages != 1) return npages;
On 13/10/2016 02:20, Lorenzo Stoakes wrote:
This patch removes the write and force parameters from __get_user_pages_unlocked() to make the use of FOLL_FORCE explicit in callers as use of this flag can result in surprising behaviour (and hence bugs) within the mm subsystem.
Signed-off-by: Lorenzo Stoakes lstoakes@gmail.com
include/linux/mm.h | 3 +-- mm/gup.c | 17 +++++++++-------- mm/nommu.c | 12 +++++++++--- mm/process_vm_access.c | 7 +++++-- virt/kvm/async_pf.c | 3 ++- virt/kvm/kvm_main.c | 11 ++++++++--- 6 files changed, 34 insertions(+), 19 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h index e9caec6..2db98b6 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1285,8 +1285,7 @@ long get_user_pages_locked(unsigned long start, unsigned long nr_pages, int write, int force, struct page **pages, int *locked); long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm, unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages,unsigned int gup_flags);
struct page **pages, unsigned int gup_flags);long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages, int write, int force, struct page **pages); int get_user_pages_fast(unsigned long start, int nr_pages, int write, diff --git a/mm/gup.c b/mm/gup.c index ba83942..3d620dd 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -865,17 +865,11 @@ EXPORT_SYMBOL(get_user_pages_locked); */ __always_inline long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm, unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages,unsigned int gup_flags)
struct page **pages, unsigned int gup_flags){ long ret; int locked = 1;
- if (write)
gup_flags |= FOLL_WRITE;- if (force)
gup_flags |= FOLL_FORCE;- down_read(&mm->mmap_sem); ret = __get_user_pages_locked(tsk, mm, start, nr_pages, pages, NULL, &locked, false, gup_flags);
@@ -905,8 +899,15 @@ EXPORT_SYMBOL(__get_user_pages_unlocked); long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages, int write, int force, struct page **pages) {
- unsigned int flags = FOLL_TOUCH;
- if (write)
flags |= FOLL_WRITE;- if (force)
flags |= FOLL_FORCE;- return __get_user_pages_unlocked(current, current->mm, start, nr_pages,
write, force, pages, FOLL_TOUCH);
pages, flags);} EXPORT_SYMBOL(get_user_pages_unlocked);
diff --git a/mm/nommu.c b/mm/nommu.c index 95daf81..925dcc1 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -185,8 +185,7 @@ EXPORT_SYMBOL(get_user_pages_locked);
long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm, unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages,unsigned int gup_flags)
struct page **pages, unsigned int gup_flags){ long ret; down_read(&mm->mmap_sem); @@ -200,8 +199,15 @@ EXPORT_SYMBOL(__get_user_pages_unlocked); long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages, int write, int force, struct page **pages) {
- unsigned int flags = 0;
- if (write)
flags |= FOLL_WRITE;- if (force)
flags |= FOLL_FORCE;- return __get_user_pages_unlocked(current, current->mm, start, nr_pages,
write, force, pages, 0);
pages, flags);} EXPORT_SYMBOL(get_user_pages_unlocked);
diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c index 07514d4..be8dc8d 100644 --- a/mm/process_vm_access.c +++ b/mm/process_vm_access.c @@ -88,12 +88,16 @@ static int process_vm_rw_single_vec(unsigned long addr, ssize_t rc = 0; unsigned long max_pages_per_loop = PVM_MAX_KMALLOC_PAGES / sizeof(struct pages *);
unsigned int flags = FOLL_REMOTE;
/* Work out address and page range required */ if (len == 0) return 0; nr_pages = (addr + len - 1) / PAGE_SIZE - addr / PAGE_SIZE + 1;
if (vm_write)
flags |= FOLL_WRITE;while (!rc && nr_pages && iov_iter_count(iter)) { int pages = min(nr_pages, max_pages_per_loop); size_t bytes;
@@ -104,8 +108,7 @@ static int process_vm_rw_single_vec(unsigned long addr, * current/current->mm */ pages = __get_user_pages_unlocked(task, mm, pa, pages,
vm_write, 0, process_pages,FOLL_REMOTE);
process_pages, flags);diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c index db96688..8035cc1 100644 --- a/virt/kvm/async_pf.c +++ b/virt/kvm/async_pf.c @@ -84,7 +84,8 @@ static void async_pf_execute(struct work_struct *work) * mm and might be done in another context, so we must * use FOLL_REMOTE. */
- __get_user_pages_unlocked(NULL, mm, addr, 1, 1, 0, NULL, FOLL_REMOTE);
__get_user_pages_unlocked(NULL, mm, addr, 1, NULL,
FOLL_WRITE | FOLL_REMOTE);kvm_async_page_present_sync(vcpu, apf);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 81dfc73..28510e7 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1416,10 +1416,15 @@ static int hva_to_pfn_slow(unsigned long addr, bool *async, bool write_fault, down_read(¤t->mm->mmap_sem); npages = get_user_page_nowait(addr, write_fault, page); up_read(¤t->mm->mmap_sem);
- } else
- } else {
unsigned int flags = FOLL_TOUCH | FOLL_HWPOISON;if (write_fault)flags |= FOLL_WRITE;- npages = __get_user_pages_unlocked(current, current->mm, addr, 1,
write_fault, 0, page,FOLL_TOUCH|FOLL_HWPOISON);
page, flags);- } if (npages != 1) return npages;
Acked-by: Paolo Bonzini pbonzini@redhat.com
On Thu 13-10-16 01:20:12, Lorenzo Stoakes wrote:
This patch removes the write and force parameters from __get_user_pages_unlocked() to make the use of FOLL_FORCE explicit in callers as use of this flag can result in surprising behaviour (and hence bugs) within the mm subsystem.
Signed-off-by: Lorenzo Stoakes lstoakes@gmail.com
The patch looks good. You can add:
Reviewed-by: Jan Kara jack@suse.cz
Honza
This patch removes the write and force parameters from get_user_pages_unlocked() and replaces them with a gup_flags parameter to make the use of FOLL_FORCE explicit in callers as use of this flag can result in surprising behaviour (and hence bugs) within the mm subsystem.
Signed-off-by: Lorenzo Stoakes lstoakes@gmail.com --- arch/mips/mm/gup.c | 2 +- arch/s390/mm/gup.c | 3 ++- arch/sh/mm/gup.c | 3 ++- arch/sparc/mm/gup.c | 3 ++- arch/x86/mm/gup.c | 2 +- drivers/media/pci/ivtv/ivtv-udma.c | 4 ++-- drivers/media/pci/ivtv/ivtv-yuv.c | 5 +++-- drivers/scsi/st.c | 5 ++--- drivers/video/fbdev/pvr2fb.c | 4 ++-- include/linux/mm.h | 2 +- mm/gup.c | 14 ++++---------- mm/nommu.c | 11 ++--------- mm/util.c | 3 ++- net/ceph/pagevec.c | 2 +- 14 files changed, 27 insertions(+), 36 deletions(-)
diff --git a/arch/mips/mm/gup.c b/arch/mips/mm/gup.c index 42d124f..d8c3c15 100644 --- a/arch/mips/mm/gup.c +++ b/arch/mips/mm/gup.c @@ -287,7 +287,7 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write, pages += nr;
ret = get_user_pages_unlocked(start, (end - start) >> PAGE_SHIFT, - write, 0, pages); + pages, write ? FOLL_WRITE : 0);
/* Have to be a bit careful with return values */ if (nr > 0) { diff --git a/arch/s390/mm/gup.c b/arch/s390/mm/gup.c index adb0c34..18d4107 100644 --- a/arch/s390/mm/gup.c +++ b/arch/s390/mm/gup.c @@ -266,7 +266,8 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write, /* Try to get the remaining pages with get_user_pages */ start += nr << PAGE_SHIFT; pages += nr; - ret = get_user_pages_unlocked(start, nr_pages - nr, write, 0, pages); + ret = get_user_pages_unlocked(start, nr_pages - nr, pages, + write ? FOLL_WRITE : 0); /* Have to be a bit careful with return values */ if (nr > 0) ret = (ret < 0) ? nr : ret + nr; diff --git a/arch/sh/mm/gup.c b/arch/sh/mm/gup.c index 40fa6c8..063c298 100644 --- a/arch/sh/mm/gup.c +++ b/arch/sh/mm/gup.c @@ -258,7 +258,8 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write, pages += nr;
ret = get_user_pages_unlocked(start, - (end - start) >> PAGE_SHIFT, write, 0, pages); + (end - start) >> PAGE_SHIFT, pages, + write ? FOLL_WRITE : 0);
/* Have to be a bit careful with return values */ if (nr > 0) { diff --git a/arch/sparc/mm/gup.c b/arch/sparc/mm/gup.c index 4e06750..cd0e32b 100644 --- a/arch/sparc/mm/gup.c +++ b/arch/sparc/mm/gup.c @@ -238,7 +238,8 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write, pages += nr;
ret = get_user_pages_unlocked(start, - (end - start) >> PAGE_SHIFT, write, 0, pages); + (end - start) >> PAGE_SHIFT, pages, + write ? FOLL_WRITE : 0);
/* Have to be a bit careful with return values */ if (nr > 0) { diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c index b8b6a60..0d4fb3e 100644 --- a/arch/x86/mm/gup.c +++ b/arch/x86/mm/gup.c @@ -435,7 +435,7 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write,
ret = get_user_pages_unlocked(start, (end - start) >> PAGE_SHIFT, - write, 0, pages); + pages, write ? FOLL_WRITE : 0);
/* Have to be a bit careful with return values */ if (nr > 0) { diff --git a/drivers/media/pci/ivtv/ivtv-udma.c b/drivers/media/pci/ivtv/ivtv-udma.c index 4769469..2c9232e 100644 --- a/drivers/media/pci/ivtv/ivtv-udma.c +++ b/drivers/media/pci/ivtv/ivtv-udma.c @@ -124,8 +124,8 @@ int ivtv_udma_setup(struct ivtv *itv, unsigned long ivtv_dest_addr, }
/* Get user pages for DMA Xfer */ - err = get_user_pages_unlocked(user_dma.uaddr, user_dma.page_count, 0, - 1, dma->map); + err = get_user_pages_unlocked(user_dma.uaddr, user_dma.page_count, + dma->map, FOLL_FORCE);
if (user_dma.page_count != err) { IVTV_DEBUG_WARN("failed to map user pages, returned %d instead of %d\n", diff --git a/drivers/media/pci/ivtv/ivtv-yuv.c b/drivers/media/pci/ivtv/ivtv-yuv.c index b094054..f7299d3 100644 --- a/drivers/media/pci/ivtv/ivtv-yuv.c +++ b/drivers/media/pci/ivtv/ivtv-yuv.c @@ -76,11 +76,12 @@ static int ivtv_yuv_prep_user_dma(struct ivtv *itv, struct ivtv_user_dma *dma,
/* Get user pages for DMA Xfer */ y_pages = get_user_pages_unlocked(y_dma.uaddr, - y_dma.page_count, 0, 1, &dma->map[0]); + y_dma.page_count, &dma->map[0], FOLL_FORCE); uv_pages = 0; /* silence gcc. value is set and consumed only if: */ if (y_pages == y_dma.page_count) { uv_pages = get_user_pages_unlocked(uv_dma.uaddr, - uv_dma.page_count, 0, 1, &dma->map[y_pages]); + uv_dma.page_count, &dma->map[y_pages], + FOLL_FORCE); }
if (y_pages != y_dma.page_count || uv_pages != uv_dma.page_count) { diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c index 7af5226..618422e 100644 --- a/drivers/scsi/st.c +++ b/drivers/scsi/st.c @@ -4922,9 +4922,8 @@ static int sgl_map_user_pages(struct st_buffer *STbp, res = get_user_pages_unlocked( uaddr, nr_pages, - rw == READ, - 0, /* don't force */ - pages); + pages, + rw == READ ? FOLL_WRITE : 0); /* don't force */
/* Errors and no page mapped should return here */ if (res < nr_pages) diff --git a/drivers/video/fbdev/pvr2fb.c b/drivers/video/fbdev/pvr2fb.c index 3b1ca44..a2564ab 100644 --- a/drivers/video/fbdev/pvr2fb.c +++ b/drivers/video/fbdev/pvr2fb.c @@ -686,8 +686,8 @@ static ssize_t pvr2fb_write(struct fb_info *info, const char *buf, if (!pages) return -ENOMEM;
- ret = get_user_pages_unlocked((unsigned long)buf, nr_pages, WRITE, - 0, pages); + ret = get_user_pages_unlocked((unsigned long)buf, nr_pages, pages, + FOLL_WRITE);
if (ret < nr_pages) { nr_pages = ret; diff --git a/include/linux/mm.h b/include/linux/mm.h index 2db98b6..6adc4bc 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1287,7 +1287,7 @@ long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm, unsigned long start, unsigned long nr_pages, struct page **pages, unsigned int gup_flags); long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages, - int write, int force, struct page **pages); + struct page **pages, unsigned int gup_flags); int get_user_pages_fast(unsigned long start, int nr_pages, int write, struct page **pages);
diff --git a/mm/gup.c b/mm/gup.c index 3d620dd..cfcb014 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -897,17 +897,10 @@ EXPORT_SYMBOL(__get_user_pages_unlocked); * "force" parameter). */ long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages, - int write, int force, struct page **pages) + struct page **pages, unsigned int gup_flags) { - unsigned int flags = FOLL_TOUCH; - - if (write) - flags |= FOLL_WRITE; - if (force) - flags |= FOLL_FORCE; - return __get_user_pages_unlocked(current, current->mm, start, nr_pages, - pages, flags); + pages, gup_flags | FOLL_TOUCH); } EXPORT_SYMBOL(get_user_pages_unlocked);
@@ -1525,7 +1518,8 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write, start += nr << PAGE_SHIFT; pages += nr;
- ret = get_user_pages_unlocked(start, nr_pages - nr, write, 0, pages); + ret = get_user_pages_unlocked(start, nr_pages - nr, pages, + write ? FOLL_WRITE : 0);
/* Have to be a bit careful with return values */ if (nr > 0) { diff --git a/mm/nommu.c b/mm/nommu.c index 925dcc1..7e27add 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -197,17 +197,10 @@ long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm, EXPORT_SYMBOL(__get_user_pages_unlocked);
long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages, - int write, int force, struct page **pages) + struct page **pages, unsigned int gup_flags) { - unsigned int flags = 0; - - if (write) - flags |= FOLL_WRITE; - if (force) - flags |= FOLL_FORCE; - return __get_user_pages_unlocked(current, current->mm, start, nr_pages, - pages, flags); + pages, gup_flags); } EXPORT_SYMBOL(get_user_pages_unlocked);
diff --git a/mm/util.c b/mm/util.c index 662cddf..4c685bd 100644 --- a/mm/util.c +++ b/mm/util.c @@ -283,7 +283,8 @@ EXPORT_SYMBOL_GPL(__get_user_pages_fast); int __weak get_user_pages_fast(unsigned long start, int nr_pages, int write, struct page **pages) { - return get_user_pages_unlocked(start, nr_pages, write, 0, pages); + return get_user_pages_unlocked(start, nr_pages, pages, + write ? FOLL_WRITE : 0); } EXPORT_SYMBOL_GPL(get_user_pages_fast);
diff --git a/net/ceph/pagevec.c b/net/ceph/pagevec.c index 00d2601..1a7c9a7 100644 --- a/net/ceph/pagevec.c +++ b/net/ceph/pagevec.c @@ -26,7 +26,7 @@ struct page **ceph_get_direct_page_vector(const void __user *data, while (got < num_pages) { rc = get_user_pages_unlocked( (unsigned long)data + ((unsigned long)got * PAGE_SIZE), - num_pages - got, write_page, 0, pages + got); + num_pages - got, pages + got, write_page ? FOLL_WRITE : 0); if (rc < 0) break; BUG_ON(rc == 0);
On Thu 13-10-16 01:20:13, Lorenzo Stoakes wrote:
This patch removes the write and force parameters from get_user_pages_unlocked() and replaces them with a gup_flags parameter to make the use of FOLL_FORCE explicit in callers as use of this flag can result in surprising behaviour (and hence bugs) within the mm subsystem.
Signed-off-by: Lorenzo Stoakes lstoakes@gmail.com
Looks good. You can add:
Reviewed-by: Jan Kara jack@suse.cz
Honza
This patch removes the write and force parameters from get_user_pages_locked() and replaces them with a gup_flags parameter to make the use of FOLL_FORCE explicit in callers as use of this flag can result in surprising behaviour (and hence bugs) within the mm subsystem.
Signed-off-by: Lorenzo Stoakes lstoakes@gmail.com --- include/linux/mm.h | 2 +- mm/frame_vector.c | 8 +++++++- mm/gup.c | 12 +++--------- mm/nommu.c | 5 ++++- 4 files changed, 15 insertions(+), 12 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h index 6adc4bc..27ab538 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1282,7 +1282,7 @@ long get_user_pages(unsigned long start, unsigned long nr_pages, int write, int force, struct page **pages, struct vm_area_struct **vmas); long get_user_pages_locked(unsigned long start, unsigned long nr_pages, - int write, int force, struct page **pages, int *locked); + unsigned int gup_flags, struct page **pages, int *locked); long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm, unsigned long start, unsigned long nr_pages, struct page **pages, unsigned int gup_flags); diff --git a/mm/frame_vector.c b/mm/frame_vector.c index 381bb07..81b6749 100644 --- a/mm/frame_vector.c +++ b/mm/frame_vector.c @@ -41,10 +41,16 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, int ret = 0; int err; int locked; + unsigned int gup_flags = 0;
if (nr_frames == 0) return 0;
+ if (write) + gup_flags |= FOLL_WRITE; + if (force) + gup_flags |= FOLL_FORCE; + if (WARN_ON_ONCE(nr_frames > vec->nr_allocated)) nr_frames = vec->nr_allocated;
@@ -59,7 +65,7 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, vec->got_ref = true; vec->is_pfns = false; ret = get_user_pages_locked(start, nr_frames, - write, force, (struct page **)(vec->ptrs), &locked); + gup_flags, (struct page **)(vec->ptrs), &locked); goto out; }
diff --git a/mm/gup.c b/mm/gup.c index cfcb014..7a0d033 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -838,18 +838,12 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk, * up_read(&mm->mmap_sem); */ long get_user_pages_locked(unsigned long start, unsigned long nr_pages, - int write, int force, struct page **pages, + unsigned int gup_flags, struct page **pages, int *locked) { - unsigned int flags = FOLL_TOUCH; - - if (write) - flags |= FOLL_WRITE; - if (force) - flags |= FOLL_FORCE; - return __get_user_pages_locked(current, current->mm, start, nr_pages, - pages, NULL, locked, true, flags); + pages, NULL, locked, true, + gup_flags | FOLL_TOUCH); } EXPORT_SYMBOL(get_user_pages_locked);
diff --git a/mm/nommu.c b/mm/nommu.c index 7e27add..842cfdd 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -176,9 +176,12 @@ long get_user_pages(unsigned long start, unsigned long nr_pages, EXPORT_SYMBOL(get_user_pages);
long get_user_pages_locked(unsigned long start, unsigned long nr_pages, - int write, int force, struct page **pages, + unsigned int gup_flags, struct page **pages, int *locked) { + int write = gup_flags & FOLL_WRITE; + int force = gup_flags & FOLL_FORCE; + return get_user_pages(start, nr_pages, write, force, pages, NULL); } EXPORT_SYMBOL(get_user_pages_locked);
On Thu 13-10-16 01:20:14, Lorenzo Stoakes wrote:
This patch removes the write and force parameters from get_user_pages_locked() and replaces them with a gup_flags parameter to make the use of FOLL_FORCE explicit in callers as use of this flag can result in surprising behaviour (and hence bugs) within the mm subsystem.
Signed-off-by: Lorenzo Stoakes lstoakes@gmail.com
include/linux/mm.h | 2 +- mm/frame_vector.c | 8 +++++++- mm/gup.c | 12 +++--------- mm/nommu.c | 5 ++++- 4 files changed, 15 insertions(+), 12 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h index 6adc4bc..27ab538 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1282,7 +1282,7 @@ long get_user_pages(unsigned long start, unsigned long nr_pages, int write, int force, struct page **pages, struct vm_area_struct **vmas); long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages, int *locked);
unsigned int gup_flags, struct page **pages, int *locked);
Hum, the prototype is inconsistent with e.g. __get_user_pages_unlocked() where gup_flags come after **pages argument. Actually it makes more sense to have it before **pages so that input arguments come first and output arguments second but I don't care that much. But it definitely should be consistent...
Honza
On Tue, Oct 18, 2016 at 02:54:25PM +0200, Jan Kara wrote:
@@ -1282,7 +1282,7 @@ long get_user_pages(unsigned long start, unsigned long nr_pages, int write, int force, struct page **pages, struct vm_area_struct **vmas); long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages, int *locked);
unsigned int gup_flags, struct page **pages, int *locked);Hum, the prototype is inconsistent with e.g. __get_user_pages_unlocked() where gup_flags come after **pages argument. Actually it makes more sense to have it before **pages so that input arguments come first and output arguments second but I don't care that much. But it definitely should be consistent...
It was difficult to decide quite how to arrange parameters as there was inconsitency with regards to parameter ordering already - for example __get_user_pages() places its flags argument before pages whereas, as you note, __get_user_pages_unlocked() puts them afterwards.
I ended up compromising by trying to match the existing ordering of the function as much as I could by replacing write, force pairs with gup_flags in the same location (with the exception of get_user_pages_unlocked() which I felt should match __get_user_pages_unlocked() in signature) or if there was already a gup_flags parameter as in the case of __get_user_pages_unlocked() I simply removed the write, force pair and left the flags as the last parameter.
I am happy to rearrange parameters as needed, however I am not sure if it'd be worthwhile for me to do so (I am keen to try to avoid adding too much noise here :)
If we were to rearrange parameters for consistency I'd suggest adjusting __get_user_pages_unlocked() to put gup_flags before pages and do the same with get_user_pages_unlocked(), let me know what you think.
On Tue 18-10-16 14:56:09, Lorenzo Stoakes wrote:
On Tue, Oct 18, 2016 at 02:54:25PM +0200, Jan Kara wrote:
@@ -1282,7 +1282,7 @@ long get_user_pages(unsigned long start, unsigned long nr_pages, int write, int force, struct page **pages, struct vm_area_struct **vmas); long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages, int *locked);
unsigned int gup_flags, struct page **pages, int *locked);Hum, the prototype is inconsistent with e.g. __get_user_pages_unlocked() where gup_flags come after **pages argument. Actually it makes more sense to have it before **pages so that input arguments come first and output arguments second but I don't care that much. But it definitely should be consistent...
It was difficult to decide quite how to arrange parameters as there was inconsitency with regards to parameter ordering already - for example __get_user_pages() places its flags argument before pages whereas, as you note, __get_user_pages_unlocked() puts them afterwards.
I ended up compromising by trying to match the existing ordering of the function as much as I could by replacing write, force pairs with gup_flags in the same location (with the exception of get_user_pages_unlocked() which I felt should match __get_user_pages_unlocked() in signature) or if there was already a gup_flags parameter as in the case of __get_user_pages_unlocked() I simply removed the write, force pair and left the flags as the last parameter.
I am happy to rearrange parameters as needed, however I am not sure if it'd be worthwhile for me to do so (I am keen to try to avoid adding too much noise here :)
If we were to rearrange parameters for consistency I'd suggest adjusting __get_user_pages_unlocked() to put gup_flags before pages and do the same with get_user_pages_unlocked(), let me know what you think.
Yeah, ok. If the inconsistency is already there, just leave it for now.
Honza
On Thu 13-10-16 01:20:14, Lorenzo Stoakes wrote:
This patch removes the write and force parameters from get_user_pages_locked() and replaces them with a gup_flags parameter to make the use of FOLL_FORCE explicit in callers as use of this flag can result in surprising behaviour (and hence bugs) within the mm subsystem.
Signed-off-by: Lorenzo Stoakes lstoakes@gmail.com
After our discussion the patch looks good to me. You can add:
Reviewed-by: Jan Kara jack@suse.cz
Honza
This patch removes the write and force parameters from get_vaddr_frames() and replaces them with a gup_flags parameter to make the use of FOLL_FORCE explicit in callers as use of this flag can result in surprising behaviour (and hence bugs) within the mm subsystem.
Signed-off-by: Lorenzo Stoakes lstoakes@gmail.com --- drivers/gpu/drm/exynos/exynos_drm_g2d.c | 3 ++- drivers/media/platform/omap/omap_vout.c | 2 +- drivers/media/v4l2-core/videobuf2-memops.c | 6 +++++- include/linux/mm.h | 2 +- mm/frame_vector.c | 13 ++----------- 5 files changed, 11 insertions(+), 15 deletions(-)
diff --git a/drivers/gpu/drm/exynos/exynos_drm_g2d.c b/drivers/gpu/drm/exynos/exynos_drm_g2d.c index aa92dec..fbd13fa 100644 --- a/drivers/gpu/drm/exynos/exynos_drm_g2d.c +++ b/drivers/gpu/drm/exynos/exynos_drm_g2d.c @@ -488,7 +488,8 @@ static dma_addr_t *g2d_userptr_get_dma_addr(struct drm_device *drm_dev, goto err_free; }
- ret = get_vaddr_frames(start, npages, true, true, g2d_userptr->vec); + ret = get_vaddr_frames(start, npages, FOLL_FORCE | FOLL_WRITE, + g2d_userptr->vec); if (ret != npages) { DRM_ERROR("failed to get user pages from userptr.\n"); if (ret < 0) diff --git a/drivers/media/platform/omap/omap_vout.c b/drivers/media/platform/omap/omap_vout.c index e668dde..a31b95c 100644 --- a/drivers/media/platform/omap/omap_vout.c +++ b/drivers/media/platform/omap/omap_vout.c @@ -214,7 +214,7 @@ static int omap_vout_get_userptr(struct videobuf_buffer *vb, u32 virtp, if (!vec) return -ENOMEM;
- ret = get_vaddr_frames(virtp, 1, true, false, vec); + ret = get_vaddr_frames(virtp, 1, FOLL_WRITE, vec); if (ret != 1) { frame_vector_destroy(vec); return -EINVAL; diff --git a/drivers/media/v4l2-core/videobuf2-memops.c b/drivers/media/v4l2-core/videobuf2-memops.c index 3c3b517..1cd322e 100644 --- a/drivers/media/v4l2-core/videobuf2-memops.c +++ b/drivers/media/v4l2-core/videobuf2-memops.c @@ -42,6 +42,10 @@ struct frame_vector *vb2_create_framevec(unsigned long start, unsigned long first, last; unsigned long nr; struct frame_vector *vec; + unsigned int flags = FOLL_FORCE; + + if (write) + flags |= FOLL_WRITE;
first = start >> PAGE_SHIFT; last = (start + length - 1) >> PAGE_SHIFT; @@ -49,7 +53,7 @@ struct frame_vector *vb2_create_framevec(unsigned long start, vec = frame_vector_create(nr); if (!vec) return ERR_PTR(-ENOMEM); - ret = get_vaddr_frames(start & PAGE_MASK, nr, write, true, vec); + ret = get_vaddr_frames(start & PAGE_MASK, nr, flags, vec); if (ret < 0) goto out_destroy; /* We accept only complete set of PFNs */ diff --git a/include/linux/mm.h b/include/linux/mm.h index 27ab538..5ff084f6 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1305,7 +1305,7 @@ struct frame_vector { struct frame_vector *frame_vector_create(unsigned int nr_frames); void frame_vector_destroy(struct frame_vector *vec); int get_vaddr_frames(unsigned long start, unsigned int nr_pfns, - bool write, bool force, struct frame_vector *vec); + unsigned int gup_flags, struct frame_vector *vec); void put_vaddr_frames(struct frame_vector *vec); int frame_vector_to_pages(struct frame_vector *vec); void frame_vector_to_pfns(struct frame_vector *vec); diff --git a/mm/frame_vector.c b/mm/frame_vector.c index 81b6749..db77dcb 100644 --- a/mm/frame_vector.c +++ b/mm/frame_vector.c @@ -11,10 +11,7 @@ * get_vaddr_frames() - map virtual addresses to pfns * @start: starting user address * @nr_frames: number of pages / pfns from start to map - * @write: whether pages will be written to by the caller - * @force: whether to force write access even if user mapping is - * readonly. See description of the same argument of - get_user_pages(). + * @gup_flags: flags modifying lookup behaviour * @vec: structure which receives pages / pfns of the addresses mapped. * It should have space for at least nr_frames entries. * @@ -34,23 +31,17 @@ * This function takes care of grabbing mmap_sem as necessary. */ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, - bool write, bool force, struct frame_vector *vec) + unsigned int gup_flags, struct frame_vector *vec) { struct mm_struct *mm = current->mm; struct vm_area_struct *vma; int ret = 0; int err; int locked; - unsigned int gup_flags = 0;
if (nr_frames == 0) return 0;
- if (write) - gup_flags |= FOLL_WRITE; - if (force) - gup_flags |= FOLL_FORCE; - if (WARN_ON_ONCE(nr_frames > vec->nr_allocated)) nr_frames = vec->nr_allocated;
On Thu 13-10-16 01:20:15, Lorenzo Stoakes wrote:
This patch removes the write and force parameters from get_vaddr_frames() and replaces them with a gup_flags parameter to make the use of FOLL_FORCE explicit in callers as use of this flag can result in surprising behaviour (and hence bugs) within the mm subsystem.
Signed-off-by: Lorenzo Stoakes lstoakes@gmail.com
Looks good. You can add:
Reviewed-by: Jan Kara jack@suse.cz
Honza
drivers/gpu/drm/exynos/exynos_drm_g2d.c | 3 ++- drivers/media/platform/omap/omap_vout.c | 2 +- drivers/media/v4l2-core/videobuf2-memops.c | 6 +++++- include/linux/mm.h | 2 +- mm/frame_vector.c | 13 ++----------- 5 files changed, 11 insertions(+), 15 deletions(-)
diff --git a/drivers/gpu/drm/exynos/exynos_drm_g2d.c b/drivers/gpu/drm/exynos/exynos_drm_g2d.c index aa92dec..fbd13fa 100644 --- a/drivers/gpu/drm/exynos/exynos_drm_g2d.c +++ b/drivers/gpu/drm/exynos/exynos_drm_g2d.c @@ -488,7 +488,8 @@ static dma_addr_t *g2d_userptr_get_dma_addr(struct drm_device *drm_dev, goto err_free; }
- ret = get_vaddr_frames(start, npages, true, true, g2d_userptr->vec);
- ret = get_vaddr_frames(start, npages, FOLL_FORCE | FOLL_WRITE,
g2d_userptr->vec);diff --git a/drivers/media/platform/omap/omap_vout.c b/drivers/media/platform/omap/omap_vout.c index e668dde..a31b95c 100644 --- a/drivers/media/platform/omap/omap_vout.c +++ b/drivers/media/platform/omap/omap_vout.c @@ -214,7 +214,7 @@ static int omap_vout_get_userptr(struct videobuf_buffer *vb, u32 virtp, if (!vec) return -ENOMEM;
- ret = get_vaddr_frames(virtp, 1, true, false, vec);
- ret = get_vaddr_frames(virtp, 1, FOLL_WRITE, vec); if (ret != 1) { frame_vector_destroy(vec); return -EINVAL;
diff --git a/drivers/media/v4l2-core/videobuf2-memops.c b/drivers/media/v4l2-core/videobuf2-memops.c index 3c3b517..1cd322e 100644 --- a/drivers/media/v4l2-core/videobuf2-memops.c +++ b/drivers/media/v4l2-core/videobuf2-memops.c @@ -42,6 +42,10 @@ struct frame_vector *vb2_create_framevec(unsigned long start, unsigned long first, last; unsigned long nr; struct frame_vector *vec;
unsigned int flags = FOLL_FORCE;
if (write)
flags |= FOLL_WRITE;first = start >> PAGE_SHIFT; last = (start + length - 1) >> PAGE_SHIFT;
@@ -49,7 +53,7 @@ struct frame_vector *vb2_create_framevec(unsigned long start, vec = frame_vector_create(nr); if (!vec) return ERR_PTR(-ENOMEM);
- ret = get_vaddr_frames(start & PAGE_MASK, nr, write, true, vec);
- ret = get_vaddr_frames(start & PAGE_MASK, nr, flags, vec); if (ret < 0) goto out_destroy; /* We accept only complete set of PFNs */
diff --git a/include/linux/mm.h b/include/linux/mm.h index 27ab538..5ff084f6 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1305,7 +1305,7 @@ struct frame_vector { struct frame_vector *frame_vector_create(unsigned int nr_frames); void frame_vector_destroy(struct frame_vector *vec); int get_vaddr_frames(unsigned long start, unsigned int nr_pfns,
bool write, bool force, struct frame_vector *vec);
unsigned int gup_flags, struct frame_vector *vec);void put_vaddr_frames(struct frame_vector *vec); int frame_vector_to_pages(struct frame_vector *vec); void frame_vector_to_pfns(struct frame_vector *vec); diff --git a/mm/frame_vector.c b/mm/frame_vector.c index 81b6749..db77dcb 100644 --- a/mm/frame_vector.c +++ b/mm/frame_vector.c @@ -11,10 +11,7 @@
- get_vaddr_frames() - map virtual addresses to pfns
- @start: starting user address
- @nr_frames: number of pages / pfns from start to map
- @write: whether pages will be written to by the caller
- @force: whether to force write access even if user mapping is
readonly. See description of the same argument ofget_user_pages().
- @gup_flags: flags modifying lookup behaviour
- @vec: structure which receives pages / pfns of the addresses mapped.
It should have space for at least nr_frames entries.@@ -34,23 +31,17 @@
- This function takes care of grabbing mmap_sem as necessary.
*/ int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
bool write, bool force, struct frame_vector *vec)
unsigned int gup_flags, struct frame_vector *vec){ struct mm_struct *mm = current->mm; struct vm_area_struct *vma; int ret = 0; int err; int locked;
unsigned int gup_flags = 0;
if (nr_frames == 0) return 0;
if (write)
gup_flags |= FOLL_WRITE;if (force)
gup_flags |= FOLL_FORCE;if (WARN_ON_ONCE(nr_frames > vec->nr_allocated)) nr_frames = vec->nr_allocated;
-- 2.10.0
This patch removes the write and force parameters from get_user_pages() and replaces them with a gup_flags parameter to make the use of FOLL_FORCE explicit in callers as use of this flag can result in surprising behaviour (and hence bugs) within the mm subsystem.
Signed-off-by: Lorenzo Stoakes lstoakes@gmail.com --- arch/cris/arch-v32/drivers/cryptocop.c | 4 +--- arch/ia64/kernel/err_inject.c | 2 +- arch/x86/mm/mpx.c | 5 ++--- drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 7 +++++-- drivers/gpu/drm/radeon/radeon_ttm.c | 3 ++- drivers/gpu/drm/via/via_dmablit.c | 4 ++-- drivers/infiniband/core/umem.c | 6 +++++- drivers/infiniband/hw/mthca/mthca_memfree.c | 2 +- drivers/infiniband/hw/qib/qib_user_pages.c | 3 ++- drivers/infiniband/hw/usnic/usnic_uiom.c | 5 ++++- drivers/media/v4l2-core/videobuf-dma-sg.c | 7 +++++-- drivers/misc/mic/scif/scif_rma.c | 3 +-- drivers/misc/sgi-gru/grufault.c | 2 +- drivers/platform/goldfish/goldfish_pipe.c | 3 ++- drivers/rapidio/devices/rio_mport_cdev.c | 3 ++- .../vc04_services/interface/vchiq_arm/vchiq_2835_arm.c | 3 +-- .../vc04_services/interface/vchiq_arm/vchiq_arm.c | 3 +-- drivers/virt/fsl_hypervisor.c | 4 ++-- include/linux/mm.h | 2 +- mm/gup.c | 12 +++--------- mm/mempolicy.c | 2 +- mm/nommu.c | 18 ++++-------------- 22 files changed, 49 insertions(+), 54 deletions(-)
diff --git a/arch/cris/arch-v32/drivers/cryptocop.c b/arch/cris/arch-v32/drivers/cryptocop.c index b5698c8..099e170 100644 --- a/arch/cris/arch-v32/drivers/cryptocop.c +++ b/arch/cris/arch-v32/drivers/cryptocop.c @@ -2722,7 +2722,6 @@ static int cryptocop_ioctl_process(struct inode *inode, struct file *filp, unsig err = get_user_pages((unsigned long int)(oper.indata + prev_ix), noinpages, 0, /* read access only for in data */ - 0, /* no force */ inpages, NULL);
@@ -2736,8 +2735,7 @@ static int cryptocop_ioctl_process(struct inode *inode, struct file *filp, unsig if (oper.do_cipher){ err = get_user_pages((unsigned long int)oper.cipher_outdata, nooutpages, - 1, /* write access for out data */ - 0, /* no force */ + FOLL_WRITE, /* write access for out data */ outpages, NULL); up_read(¤t->mm->mmap_sem); diff --git a/arch/ia64/kernel/err_inject.c b/arch/ia64/kernel/err_inject.c index 09f8457..5ed0ea9 100644 --- a/arch/ia64/kernel/err_inject.c +++ b/arch/ia64/kernel/err_inject.c @@ -142,7 +142,7 @@ store_virtual_to_phys(struct device *dev, struct device_attribute *attr, u64 virt_addr=simple_strtoull(buf, NULL, 16); int ret;
- ret = get_user_pages(virt_addr, 1, VM_READ, 0, NULL, NULL); + ret = get_user_pages(virt_addr, 1, FOLL_WRITE, NULL, NULL); if (ret<=0) { #ifdef ERR_INJ_DEBUG printk("Virtual address %lx is not existing.\n",virt_addr); diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c index 8047687..e4f8009 100644 --- a/arch/x86/mm/mpx.c +++ b/arch/x86/mm/mpx.c @@ -544,10 +544,9 @@ static int mpx_resolve_fault(long __user *addr, int write) { long gup_ret; int nr_pages = 1; - int force = 0;
- gup_ret = get_user_pages((unsigned long)addr, nr_pages, write, - force, NULL, NULL); + gup_ret = get_user_pages((unsigned long)addr, nr_pages, + write ? FOLL_WRITE : 0, NULL, NULL); /* * get_user_pages() returns number of pages gotten. * 0 means we failed to fault in and get anything, diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c index 887483b..dcaf691 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c @@ -555,10 +555,13 @@ struct amdgpu_ttm_tt { int amdgpu_ttm_tt_get_user_pages(struct ttm_tt *ttm, struct page **pages) { struct amdgpu_ttm_tt *gtt = (void *)ttm; - int write = !(gtt->userflags & AMDGPU_GEM_USERPTR_READONLY); + unsigned int flags = 0; unsigned pinned = 0; int r;
+ if (!(gtt->userflags & AMDGPU_GEM_USERPTR_READONLY)) + flags |= FOLL_WRITE; + if (gtt->userflags & AMDGPU_GEM_USERPTR_ANONONLY) { /* check that we only use anonymous memory to prevent problems with writeback */ @@ -581,7 +584,7 @@ int amdgpu_ttm_tt_get_user_pages(struct ttm_tt *ttm, struct page **pages) list_add(&guptask.list, >t->guptasks); spin_unlock(>t->guptasklock);
- r = get_user_pages(userptr, num_pages, write, 0, p, NULL); + r = get_user_pages(userptr, num_pages, flags, p, NULL);
spin_lock(>t->guptasklock); list_del(&guptask.list); diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c b/drivers/gpu/drm/radeon/radeon_ttm.c index 4552682..3de5e6e 100644 --- a/drivers/gpu/drm/radeon/radeon_ttm.c +++ b/drivers/gpu/drm/radeon/radeon_ttm.c @@ -566,7 +566,8 @@ static int radeon_ttm_tt_pin_userptr(struct ttm_tt *ttm) uint64_t userptr = gtt->userptr + pinned * PAGE_SIZE; struct page **pages = ttm->pages + pinned;
- r = get_user_pages(userptr, num_pages, write, 0, pages, NULL); + r = get_user_pages(userptr, num_pages, write ? FOLL_WRITE : 0, + pages, NULL); if (r < 0) goto release_pages;
diff --git a/drivers/gpu/drm/via/via_dmablit.c b/drivers/gpu/drm/via/via_dmablit.c index 7e2a12c..1a3ad76 100644 --- a/drivers/gpu/drm/via/via_dmablit.c +++ b/drivers/gpu/drm/via/via_dmablit.c @@ -241,8 +241,8 @@ via_lock_all_dma_pages(drm_via_sg_info_t *vsg, drm_via_dmablit_t *xfer) down_read(¤t->mm->mmap_sem); ret = get_user_pages((unsigned long)xfer->mem_addr, vsg->num_pages, - (vsg->direction == DMA_FROM_DEVICE), - 0, vsg->pages, NULL); + (vsg->direction == DMA_FROM_DEVICE) ? FOLL_WRITE : 0, + vsg->pages, NULL);
up_read(¤t->mm->mmap_sem); if (ret != vsg->num_pages) { diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c index c68746c..224ad27 100644 --- a/drivers/infiniband/core/umem.c +++ b/drivers/infiniband/core/umem.c @@ -94,6 +94,7 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr, unsigned long dma_attrs = 0; struct scatterlist *sg, *sg_list_start; int need_release = 0; + unsigned int gup_flags = FOLL_WRITE;
if (dmasync) dma_attrs |= DMA_ATTR_WRITE_BARRIER; @@ -183,6 +184,9 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr, if (ret) goto out;
+ if (!umem->writable) + gup_flags |= FOLL_FORCE; + need_release = 1; sg_list_start = umem->sg_head.sgl;
@@ -190,7 +194,7 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr, ret = get_user_pages(cur_base, min_t(unsigned long, npages, PAGE_SIZE / sizeof (struct page *)), - 1, !umem->writable, page_list, vma_list); + gup_flags, page_list, vma_list);
if (ret < 0) goto out; diff --git a/drivers/infiniband/hw/mthca/mthca_memfree.c b/drivers/infiniband/hw/mthca/mthca_memfree.c index 6c00d04..c6fe89d 100644 --- a/drivers/infiniband/hw/mthca/mthca_memfree.c +++ b/drivers/infiniband/hw/mthca/mthca_memfree.c @@ -472,7 +472,7 @@ int mthca_map_user_db(struct mthca_dev *dev, struct mthca_uar *uar, goto out; }
- ret = get_user_pages(uaddr & PAGE_MASK, 1, 1, 0, pages, NULL); + ret = get_user_pages(uaddr & PAGE_MASK, 1, FOLL_WRITE, pages, NULL); if (ret < 0) goto out;
diff --git a/drivers/infiniband/hw/qib/qib_user_pages.c b/drivers/infiniband/hw/qib/qib_user_pages.c index 2d2b94f..75f0862 100644 --- a/drivers/infiniband/hw/qib/qib_user_pages.c +++ b/drivers/infiniband/hw/qib/qib_user_pages.c @@ -67,7 +67,8 @@ static int __qib_get_user_pages(unsigned long start_page, size_t num_pages,
for (got = 0; got < num_pages; got += ret) { ret = get_user_pages(start_page + got * PAGE_SIZE, - num_pages - got, 1, 1, + num_pages - got, + FOLL_WRITE | FOLL_FORCE, p + got, NULL); if (ret < 0) goto bail_release; diff --git a/drivers/infiniband/hw/usnic/usnic_uiom.c b/drivers/infiniband/hw/usnic/usnic_uiom.c index a0b6ebe..1ccee6e 100644 --- a/drivers/infiniband/hw/usnic/usnic_uiom.c +++ b/drivers/infiniband/hw/usnic/usnic_uiom.c @@ -111,6 +111,7 @@ static int usnic_uiom_get_pages(unsigned long addr, size_t size, int writable, int i; int flags; dma_addr_t pa; + unsigned int gup_flags;
if (!can_do_mlock()) return -EPERM; @@ -135,6 +136,8 @@ static int usnic_uiom_get_pages(unsigned long addr, size_t size, int writable,
flags = IOMMU_READ | IOMMU_CACHE; flags |= (writable) ? IOMMU_WRITE : 0; + gup_flags = FOLL_WRITE; + gup_flags |= (writable) ? 0 : FOLL_FORCE; cur_base = addr & PAGE_MASK; ret = 0;
@@ -142,7 +145,7 @@ static int usnic_uiom_get_pages(unsigned long addr, size_t size, int writable, ret = get_user_pages(cur_base, min_t(unsigned long, npages, PAGE_SIZE / sizeof(struct page *)), - 1, !writable, page_list, NULL); + gup_flags, page_list, NULL);
if (ret < 0) goto out; diff --git a/drivers/media/v4l2-core/videobuf-dma-sg.c b/drivers/media/v4l2-core/videobuf-dma-sg.c index f300f06..1db0af6 100644 --- a/drivers/media/v4l2-core/videobuf-dma-sg.c +++ b/drivers/media/v4l2-core/videobuf-dma-sg.c @@ -156,6 +156,7 @@ static int videobuf_dma_init_user_locked(struct videobuf_dmabuf *dma, { unsigned long first, last; int err, rw = 0; + unsigned int flags = FOLL_FORCE;
dma->direction = direction; switch (dma->direction) { @@ -178,12 +179,14 @@ static int videobuf_dma_init_user_locked(struct videobuf_dmabuf *dma, if (NULL == dma->pages) return -ENOMEM;
+ if (rw == READ) + flags |= FOLL_WRITE; + dprintk(1, "init user [0x%lx+0x%lx => %d pages]\n", data, size, dma->nr_pages);
err = get_user_pages(data & PAGE_MASK, dma->nr_pages, - rw == READ, 1, /* force */ - dma->pages, NULL); + flags, dma->pages, NULL);
if (err != dma->nr_pages) { dma->nr_pages = (err >= 0) ? err : 0; diff --git a/drivers/misc/mic/scif/scif_rma.c b/drivers/misc/mic/scif/scif_rma.c index e0203b1..f806a44 100644 --- a/drivers/misc/mic/scif/scif_rma.c +++ b/drivers/misc/mic/scif/scif_rma.c @@ -1396,8 +1396,7 @@ int __scif_pin_pages(void *addr, size_t len, int *out_prot, pinned_pages->nr_pages = get_user_pages( (u64)addr, nr_pages, - !!(prot & SCIF_PROT_WRITE), - 0, + (prot & SCIF_PROT_WRITE) ? FOLL_WRITE : 0, pinned_pages->pages, NULL); up_write(&mm->mmap_sem); diff --git a/drivers/misc/sgi-gru/grufault.c b/drivers/misc/sgi-gru/grufault.c index a2d97b9..6fb773d 100644 --- a/drivers/misc/sgi-gru/grufault.c +++ b/drivers/misc/sgi-gru/grufault.c @@ -198,7 +198,7 @@ static int non_atomic_pte_lookup(struct vm_area_struct *vma, #else *pageshift = PAGE_SHIFT; #endif - if (get_user_pages(vaddr, 1, write, 0, &page, NULL) <= 0) + if (get_user_pages(vaddr, 1, write ? FOLL_WRITE : 0, &page, NULL) <= 0) return -EFAULT; *paddr = page_to_phys(page); put_page(page); diff --git a/drivers/platform/goldfish/goldfish_pipe.c b/drivers/platform/goldfish/goldfish_pipe.c index 07462d7..1aba2c7 100644 --- a/drivers/platform/goldfish/goldfish_pipe.c +++ b/drivers/platform/goldfish/goldfish_pipe.c @@ -309,7 +309,8 @@ static ssize_t goldfish_pipe_read_write(struct file *filp, char __user *buffer, * much memory to the process. */ down_read(¤t->mm->mmap_sem); - ret = get_user_pages(address, 1, !is_write, 0, &page, NULL); + ret = get_user_pages(address, 1, is_write ? 0 : FOLL_WRITE, + &page, NULL); up_read(¤t->mm->mmap_sem); if (ret < 0) break; diff --git a/drivers/rapidio/devices/rio_mport_cdev.c b/drivers/rapidio/devices/rio_mport_cdev.c index 436dfe8..9013a58 100644 --- a/drivers/rapidio/devices/rio_mport_cdev.c +++ b/drivers/rapidio/devices/rio_mport_cdev.c @@ -892,7 +892,8 @@ rio_dma_transfer(struct file *filp, u32 transfer_mode, down_read(¤t->mm->mmap_sem); pinned = get_user_pages( (unsigned long)xfer->loc_addr & PAGE_MASK, - nr_pages, dir == DMA_FROM_DEVICE, 0, + nr_pages, + dir == DMA_FROM_DEVICE ? FOLL_WRITE : 0, page_list, NULL); up_read(¤t->mm->mmap_sem);
diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c index c29040f..1091b9f 100644 --- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c @@ -423,8 +423,7 @@ create_pagelist(char __user *buf, size_t count, unsigned short type, actual_pages = get_user_pages(task, task->mm, (unsigned long)buf & ~(PAGE_SIZE - 1), num_pages, - (type == PAGELIST_READ) /*Write */ , - 0 /*Force */ , + (type == PAGELIST_READ) ? FOLL_WRITE : 0, pages, NULL /*vmas */); up_read(&task->mm->mmap_sem); diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c index e11c0e0..7b6cd4d 100644 --- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c @@ -1477,8 +1477,7 @@ dump_phys_mem(void *virt_addr, uint32_t num_bytes) current->mm, /* mm */ (unsigned long)virt_addr, /* start */ num_pages, /* len */ - 0, /* write */ - 0, /* force */ + 0, /* gup_flags */ pages, /* pages (array of page pointers) */ NULL); /* vmas */ up_read(¤t->mm->mmap_sem); diff --git a/drivers/virt/fsl_hypervisor.c b/drivers/virt/fsl_hypervisor.c index 60bdad3..150ce2a 100644 --- a/drivers/virt/fsl_hypervisor.c +++ b/drivers/virt/fsl_hypervisor.c @@ -245,8 +245,8 @@ static long ioctl_memcpy(struct fsl_hv_ioctl_memcpy __user *p) /* Get the physical addresses of the source buffer */ down_read(¤t->mm->mmap_sem); num_pinned = get_user_pages(param.local_vaddr - lb_offset, - num_pages, (param.source == -1) ? READ : WRITE, - 0, pages, NULL); + num_pages, (param.source == -1) ? 0 : FOLL_WRITE, + pages, NULL); up_read(¤t->mm->mmap_sem);
if (num_pinned != num_pages) { diff --git a/include/linux/mm.h b/include/linux/mm.h index 5ff084f6..686a477 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1279,7 +1279,7 @@ long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm, int write, int force, struct page **pages, struct vm_area_struct **vmas); long get_user_pages(unsigned long start, unsigned long nr_pages, - int write, int force, struct page **pages, + unsigned int gup_flags, struct page **pages, struct vm_area_struct **vmas); long get_user_pages_locked(unsigned long start, unsigned long nr_pages, unsigned int gup_flags, struct page **pages, int *locked); diff --git a/mm/gup.c b/mm/gup.c index 7a0d033..dc91303 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -977,18 +977,12 @@ EXPORT_SYMBOL(get_user_pages_remote); * obviously don't pass FOLL_REMOTE in here. */ long get_user_pages(unsigned long start, unsigned long nr_pages, - int write, int force, struct page **pages, + unsigned int gup_flags, struct page **pages, struct vm_area_struct **vmas) { - unsigned int flags = FOLL_TOUCH; - - if (write) - flags |= FOLL_WRITE; - if (force) - flags |= FOLL_FORCE; - return __get_user_pages_locked(current, current->mm, start, nr_pages, - pages, vmas, NULL, false, flags); + pages, vmas, NULL, false, + gup_flags | FOLL_TOUCH); } EXPORT_SYMBOL(get_user_pages);
diff --git a/mm/mempolicy.c b/mm/mempolicy.c index ad1c96a..0b859af 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -850,7 +850,7 @@ static int lookup_node(unsigned long addr) struct page *p; int err;
- err = get_user_pages(addr & PAGE_MASK, 1, 0, 0, &p, NULL); + err = get_user_pages(addr & PAGE_MASK, 1, 0, &p, NULL); if (err >= 0) { err = page_to_nid(p); put_page(p); diff --git a/mm/nommu.c b/mm/nommu.c index 842cfdd..70cb844 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -160,18 +160,11 @@ long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, * - don't permit access to VMAs that don't support it, such as I/O mappings */ long get_user_pages(unsigned long start, unsigned long nr_pages, - int write, int force, struct page **pages, + unsigned int gup_flags, struct page **pages, struct vm_area_struct **vmas) { - int flags = 0; - - if (write) - flags |= FOLL_WRITE; - if (force) - flags |= FOLL_FORCE; - - return __get_user_pages(current, current->mm, start, nr_pages, flags, - pages, vmas, NULL); + return __get_user_pages(current, current->mm, start, nr_pages, + gup_flags, pages, vmas, NULL); } EXPORT_SYMBOL(get_user_pages);
@@ -179,10 +172,7 @@ long get_user_pages_locked(unsigned long start, unsigned long nr_pages, unsigned int gup_flags, struct page **pages, int *locked) { - int write = gup_flags & FOLL_WRITE; - int force = gup_flags & FOLL_FORCE; - - return get_user_pages(start, nr_pages, write, force, pages, NULL); + return get_user_pages(start, nr_pages, gup_flags, pages, NULL); } EXPORT_SYMBOL(get_user_pages_locked);
On Thu, Oct 13, 2016 at 01:20:16AM +0100, Lorenzo Stoakes wrote:
This patch removes the write and force parameters from get_user_pages() and replaces them with a gup_flags parameter to make the use of FOLL_FORCE explicit in callers as use of this flag can result in surprising behaviour (and hence bugs) within the mm subsystem.
Signed-off-by: Lorenzo Stoakes lstoakes@gmail.com
arch/cris/arch-v32/drivers/cryptocop.c | 4 +---
For the CRIS part:
Acked-by: Jesper Nilsson jesper.nilsson@axis.com
/^JN - Jesper Nilsson
On Thu 13-10-16 01:20:16, Lorenzo Stoakes wrote:
This patch removes the write and force parameters from get_user_pages() and replaces them with a gup_flags parameter to make the use of FOLL_FORCE explicit in callers as use of this flag can result in surprising behaviour (and hence bugs) within the mm subsystem.
Signed-off-by: Lorenzo Stoakes lstoakes@gmail.com
The patch looks good. You can add:
Reviewed-by: Jan Kara jack@suse.cz
Honza
arch/cris/arch-v32/drivers/cryptocop.c | 4 +--- arch/ia64/kernel/err_inject.c | 2 +- arch/x86/mm/mpx.c | 5 ++--- drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 7 +++++-- drivers/gpu/drm/radeon/radeon_ttm.c | 3 ++- drivers/gpu/drm/via/via_dmablit.c | 4 ++-- drivers/infiniband/core/umem.c | 6 +++++- drivers/infiniband/hw/mthca/mthca_memfree.c | 2 +- drivers/infiniband/hw/qib/qib_user_pages.c | 3 ++- drivers/infiniband/hw/usnic/usnic_uiom.c | 5 ++++- drivers/media/v4l2-core/videobuf-dma-sg.c | 7 +++++-- drivers/misc/mic/scif/scif_rma.c | 3 +-- drivers/misc/sgi-gru/grufault.c | 2 +- drivers/platform/goldfish/goldfish_pipe.c | 3 ++- drivers/rapidio/devices/rio_mport_cdev.c | 3 ++- .../vc04_services/interface/vchiq_arm/vchiq_2835_arm.c | 3 +-- .../vc04_services/interface/vchiq_arm/vchiq_arm.c | 3 +-- drivers/virt/fsl_hypervisor.c | 4 ++-- include/linux/mm.h | 2 +- mm/gup.c | 12 +++--------- mm/mempolicy.c | 2 +- mm/nommu.c | 18 ++++-------------- 22 files changed, 49 insertions(+), 54 deletions(-)
diff --git a/arch/cris/arch-v32/drivers/cryptocop.c b/arch/cris/arch-v32/drivers/cryptocop.c index b5698c8..099e170 100644 --- a/arch/cris/arch-v32/drivers/cryptocop.c +++ b/arch/cris/arch-v32/drivers/cryptocop.c @@ -2722,7 +2722,6 @@ static int cryptocop_ioctl_process(struct inode *inode, struct file *filp, unsig err = get_user_pages((unsigned long int)(oper.indata + prev_ix), noinpages, 0, /* read access only for in data */
0, /* no force */ inpages, NULL);@@ -2736,8 +2735,7 @@ static int cryptocop_ioctl_process(struct inode *inode, struct file *filp, unsig if (oper.do_cipher){ err = get_user_pages((unsigned long int)oper.cipher_outdata, nooutpages,
1, /* write access for out data */0, /* no force */
FOLL_WRITE, /* write access for out data */ outpages, NULL);diff --git a/arch/ia64/kernel/err_inject.c b/arch/ia64/kernel/err_inject.c index 09f8457..5ed0ea9 100644 --- a/arch/ia64/kernel/err_inject.c +++ b/arch/ia64/kernel/err_inject.c @@ -142,7 +142,7 @@ store_virtual_to_phys(struct device *dev, struct device_attribute *attr, u64 virt_addr=simple_strtoull(buf, NULL, 16); int ret;
- ret = get_user_pages(virt_addr, 1, VM_READ, 0, NULL, NULL);
- ret = get_user_pages(virt_addr, 1, FOLL_WRITE, NULL, NULL); if (ret<=0) {
#ifdef ERR_INJ_DEBUG printk("Virtual address %lx is not existing.\n",virt_addr); diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c index 8047687..e4f8009 100644 --- a/arch/x86/mm/mpx.c +++ b/arch/x86/mm/mpx.c @@ -544,10 +544,9 @@ static int mpx_resolve_fault(long __user *addr, int write) { long gup_ret; int nr_pages = 1;
int force = 0;
gup_ret = get_user_pages((unsigned long)addr, nr_pages, write,
force, NULL, NULL);
- gup_ret = get_user_pages((unsigned long)addr, nr_pages,
write ? FOLL_WRITE : 0, NULL, NULL);
- get_user_pages() returns number of pages gotten.
- 0 means we failed to fault in and get anything,
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c index 887483b..dcaf691 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c @@ -555,10 +555,13 @@ struct amdgpu_ttm_tt { int amdgpu_ttm_tt_get_user_pages(struct ttm_tt *ttm, struct page **pages) { struct amdgpu_ttm_tt *gtt = (void *)ttm;
- int write = !(gtt->userflags & AMDGPU_GEM_USERPTR_READONLY);
unsigned int flags = 0; unsigned pinned = 0; int r;
if (!(gtt->userflags & AMDGPU_GEM_USERPTR_READONLY))
flags |= FOLL_WRITE;if (gtt->userflags & AMDGPU_GEM_USERPTR_ANONONLY) { /* check that we only use anonymous memory to prevent problems with writeback */
@@ -581,7 +584,7 @@ int amdgpu_ttm_tt_get_user_pages(struct ttm_tt *ttm, struct page **pages) list_add(&guptask.list, >t->guptasks); spin_unlock(>t->guptasklock);
r = get_user_pages(userptr, num_pages, write, 0, p, NULL);
r = get_user_pages(userptr, num_pages, flags, p, NULL);spin_lock(>t->guptasklock); list_del(&guptask.list);
diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c b/drivers/gpu/drm/radeon/radeon_ttm.c index 4552682..3de5e6e 100644 --- a/drivers/gpu/drm/radeon/radeon_ttm.c +++ b/drivers/gpu/drm/radeon/radeon_ttm.c @@ -566,7 +566,8 @@ static int radeon_ttm_tt_pin_userptr(struct ttm_tt *ttm) uint64_t userptr = gtt->userptr + pinned * PAGE_SIZE; struct page **pages = ttm->pages + pinned;
r = get_user_pages(userptr, num_pages, write, 0, pages, NULL);
r = get_user_pages(userptr, num_pages, write ? FOLL_WRITE : 0,pages, NULL);diff --git a/drivers/gpu/drm/via/via_dmablit.c b/drivers/gpu/drm/via/via_dmablit.c index 7e2a12c..1a3ad76 100644 --- a/drivers/gpu/drm/via/via_dmablit.c +++ b/drivers/gpu/drm/via/via_dmablit.c @@ -241,8 +241,8 @@ via_lock_all_dma_pages(drm_via_sg_info_t *vsg, drm_via_dmablit_t *xfer) down_read(¤t->mm->mmap_sem); ret = get_user_pages((unsigned long)xfer->mem_addr, vsg->num_pages,
(vsg->direction == DMA_FROM_DEVICE),0, vsg->pages, NULL);
(vsg->direction == DMA_FROM_DEVICE) ? FOLL_WRITE : 0,vsg->pages, NULL);up_read(¤t->mm->mmap_sem); if (ret != vsg->num_pages) {
diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c index c68746c..224ad27 100644 --- a/drivers/infiniband/core/umem.c +++ b/drivers/infiniband/core/umem.c @@ -94,6 +94,7 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr, unsigned long dma_attrs = 0; struct scatterlist *sg, *sg_list_start; int need_release = 0;
unsigned int gup_flags = FOLL_WRITE;
if (dmasync) dma_attrs |= DMA_ATTR_WRITE_BARRIER;
@@ -183,6 +184,9 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr, if (ret) goto out;
- if (!umem->writable)
gup_flags |= FOLL_FORCE;- need_release = 1; sg_list_start = umem->sg_head.sgl;
@@ -190,7 +194,7 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr, ret = get_user_pages(cur_base, min_t(unsigned long, npages, PAGE_SIZE / sizeof (struct page *)),
1, !umem->writable, page_list, vma_list);
gup_flags, page_list, vma_list);if (ret < 0) goto out;
diff --git a/drivers/infiniband/hw/mthca/mthca_memfree.c b/drivers/infiniband/hw/mthca/mthca_memfree.c index 6c00d04..c6fe89d 100644 --- a/drivers/infiniband/hw/mthca/mthca_memfree.c +++ b/drivers/infiniband/hw/mthca/mthca_memfree.c @@ -472,7 +472,7 @@ int mthca_map_user_db(struct mthca_dev *dev, struct mthca_uar *uar, goto out; }
- ret = get_user_pages(uaddr & PAGE_MASK, 1, 1, 0, pages, NULL);
- ret = get_user_pages(uaddr & PAGE_MASK, 1, FOLL_WRITE, pages, NULL); if (ret < 0) goto out;
diff --git a/drivers/infiniband/hw/qib/qib_user_pages.c b/drivers/infiniband/hw/qib/qib_user_pages.c index 2d2b94f..75f0862 100644 --- a/drivers/infiniband/hw/qib/qib_user_pages.c +++ b/drivers/infiniband/hw/qib/qib_user_pages.c @@ -67,7 +67,8 @@ static int __qib_get_user_pages(unsigned long start_page, size_t num_pages,
for (got = 0; got < num_pages; got += ret) { ret = get_user_pages(start_page + got * PAGE_SIZE,
num_pages - got, 1, 1,
num_pages - got,FOLL_WRITE | FOLL_FORCE, p + got, NULL);diff --git a/drivers/infiniband/hw/usnic/usnic_uiom.c b/drivers/infiniband/hw/usnic/usnic_uiom.c index a0b6ebe..1ccee6e 100644 --- a/drivers/infiniband/hw/usnic/usnic_uiom.c +++ b/drivers/infiniband/hw/usnic/usnic_uiom.c @@ -111,6 +111,7 @@ static int usnic_uiom_get_pages(unsigned long addr, size_t size, int writable, int i; int flags; dma_addr_t pa;
unsigned int gup_flags;
if (!can_do_mlock()) return -EPERM;
@@ -135,6 +136,8 @@ static int usnic_uiom_get_pages(unsigned long addr, size_t size, int writable,
flags = IOMMU_READ | IOMMU_CACHE; flags |= (writable) ? IOMMU_WRITE : 0;
- gup_flags = FOLL_WRITE;
- gup_flags |= (writable) ? 0 : FOLL_FORCE; cur_base = addr & PAGE_MASK; ret = 0;
@@ -142,7 +145,7 @@ static int usnic_uiom_get_pages(unsigned long addr, size_t size, int writable, ret = get_user_pages(cur_base, min_t(unsigned long, npages, PAGE_SIZE / sizeof(struct page *)),
1, !writable, page_list, NULL);
gup_flags, page_list, NULL);if (ret < 0) goto out;
diff --git a/drivers/media/v4l2-core/videobuf-dma-sg.c b/drivers/media/v4l2-core/videobuf-dma-sg.c index f300f06..1db0af6 100644 --- a/drivers/media/v4l2-core/videobuf-dma-sg.c +++ b/drivers/media/v4l2-core/videobuf-dma-sg.c @@ -156,6 +156,7 @@ static int videobuf_dma_init_user_locked(struct videobuf_dmabuf *dma, { unsigned long first, last; int err, rw = 0;
unsigned int flags = FOLL_FORCE;
dma->direction = direction; switch (dma->direction) {
@@ -178,12 +179,14 @@ static int videobuf_dma_init_user_locked(struct videobuf_dmabuf *dma, if (NULL == dma->pages) return -ENOMEM;
if (rw == READ)
flags |= FOLL_WRITE;dprintk(1, "init user [0x%lx+0x%lx => %d pages]\n", data, size, dma->nr_pages);
err = get_user_pages(data & PAGE_MASK, dma->nr_pages,
rw == READ, 1, /* force */dma->pages, NULL);
flags, dma->pages, NULL);if (err != dma->nr_pages) { dma->nr_pages = (err >= 0) ? err : 0;
diff --git a/drivers/misc/mic/scif/scif_rma.c b/drivers/misc/mic/scif/scif_rma.c index e0203b1..f806a44 100644 --- a/drivers/misc/mic/scif/scif_rma.c +++ b/drivers/misc/mic/scif/scif_rma.c @@ -1396,8 +1396,7 @@ int __scif_pin_pages(void *addr, size_t len, int *out_prot, pinned_pages->nr_pages = get_user_pages( (u64)addr, nr_pages,
!!(prot & SCIF_PROT_WRITE),0,
(prot & SCIF_PROT_WRITE) ? FOLL_WRITE : 0, pinned_pages->pages, NULL);diff --git a/drivers/misc/sgi-gru/grufault.c b/drivers/misc/sgi-gru/grufault.c index a2d97b9..6fb773d 100644 --- a/drivers/misc/sgi-gru/grufault.c +++ b/drivers/misc/sgi-gru/grufault.c @@ -198,7 +198,7 @@ static int non_atomic_pte_lookup(struct vm_area_struct *vma, #else *pageshift = PAGE_SHIFT; #endif
- if (get_user_pages(vaddr, 1, write, 0, &page, NULL) <= 0)
- if (get_user_pages(vaddr, 1, write ? FOLL_WRITE : 0, &page, NULL) <= 0) return -EFAULT; *paddr = page_to_phys(page); put_page(page);
diff --git a/drivers/platform/goldfish/goldfish_pipe.c b/drivers/platform/goldfish/goldfish_pipe.c index 07462d7..1aba2c7 100644 --- a/drivers/platform/goldfish/goldfish_pipe.c +++ b/drivers/platform/goldfish/goldfish_pipe.c @@ -309,7 +309,8 @@ static ssize_t goldfish_pipe_read_write(struct file *filp, char __user *buffer, * much memory to the process. */ down_read(¤t->mm->mmap_sem);
ret = get_user_pages(address, 1, !is_write, 0, &page, NULL);
ret = get_user_pages(address, 1, is_write ? 0 : FOLL_WRITE,&page, NULL);diff --git a/drivers/rapidio/devices/rio_mport_cdev.c b/drivers/rapidio/devices/rio_mport_cdev.c index 436dfe8..9013a58 100644 --- a/drivers/rapidio/devices/rio_mport_cdev.c +++ b/drivers/rapidio/devices/rio_mport_cdev.c @@ -892,7 +892,8 @@ rio_dma_transfer(struct file *filp, u32 transfer_mode, down_read(¤t->mm->mmap_sem); pinned = get_user_pages( (unsigned long)xfer->loc_addr & PAGE_MASK,
nr_pages, dir == DMA_FROM_DEVICE, 0,
nr_pages,dir == DMA_FROM_DEVICE ? FOLL_WRITE : 0, page_list, NULL);diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c index c29040f..1091b9f 100644 --- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c @@ -423,8 +423,7 @@ create_pagelist(char __user *buf, size_t count, unsigned short type, actual_pages = get_user_pages(task, task->mm, (unsigned long)buf & ~(PAGE_SIZE - 1), num_pages,
(type == PAGELIST_READ) /*Write */ ,0 /*Force */ ,
(type == PAGELIST_READ) ? FOLL_WRITE : 0, pages, NULL /*vmas */);diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c index e11c0e0..7b6cd4d 100644 --- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c @@ -1477,8 +1477,7 @@ dump_phys_mem(void *virt_addr, uint32_t num_bytes) current->mm, /* mm */ (unsigned long)virt_addr, /* start */ num_pages, /* len */
0, /* write */0, /* force */
0, /* gup_flags */diff --git a/drivers/virt/fsl_hypervisor.c b/drivers/virt/fsl_hypervisor.c index 60bdad3..150ce2a 100644 --- a/drivers/virt/fsl_hypervisor.c +++ b/drivers/virt/fsl_hypervisor.c @@ -245,8 +245,8 @@ static long ioctl_memcpy(struct fsl_hv_ioctl_memcpy __user *p) /* Get the physical addresses of the source buffer */ down_read(¤t->mm->mmap_sem); num_pinned = get_user_pages(param.local_vaddr - lb_offset,
num_pages, (param.source == -1) ? READ : WRITE,0, pages, NULL);
num_pages, (param.source == -1) ? 0 : FOLL_WRITE,pages, NULL);up_read(¤t->mm->mmap_sem);
if (num_pinned != num_pages) {
diff --git a/include/linux/mm.h b/include/linux/mm.h index 5ff084f6..686a477 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1279,7 +1279,7 @@ long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm, int write, int force, struct page **pages, struct vm_area_struct **vmas); long get_user_pages(unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages,
unsigned int gup_flags, struct page **pages, struct vm_area_struct **vmas);long get_user_pages_locked(unsigned long start, unsigned long nr_pages, unsigned int gup_flags, struct page **pages, int *locked); diff --git a/mm/gup.c b/mm/gup.c index 7a0d033..dc91303 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -977,18 +977,12 @@ EXPORT_SYMBOL(get_user_pages_remote);
- obviously don't pass FOLL_REMOTE in here.
*/ long get_user_pages(unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages,
unsigned int gup_flags, struct page **pages,{
- unsigned int flags = FOLL_TOUCH;
- if (write)
flags |= FOLL_WRITE;- if (force)
flags |= FOLL_FORCE;- return __get_user_pages_locked(current, current->mm, start, nr_pages,
pages, vmas, NULL, false, flags);
pages, vmas, NULL, false,gup_flags | FOLL_TOUCH);} EXPORT_SYMBOL(get_user_pages);
diff --git a/mm/mempolicy.c b/mm/mempolicy.c index ad1c96a..0b859af 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -850,7 +850,7 @@ static int lookup_node(unsigned long addr) struct page *p; int err;
- err = get_user_pages(addr & PAGE_MASK, 1, 0, 0, &p, NULL);
- err = get_user_pages(addr & PAGE_MASK, 1, 0, &p, NULL); if (err >= 0) { err = page_to_nid(p); put_page(p);
diff --git a/mm/nommu.c b/mm/nommu.c index 842cfdd..70cb844 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -160,18 +160,11 @@ long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
- don't permit access to VMAs that don't support it, such as I/O mappings
*/ long get_user_pages(unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages,
unsigned int gup_flags, struct page **pages,{
- int flags = 0;
- if (write)
flags |= FOLL_WRITE;- if (force)
flags |= FOLL_FORCE;- return __get_user_pages(current, current->mm, start, nr_pages, flags,
pages, vmas, NULL);
- return __get_user_pages(current, current->mm, start, nr_pages,
gup_flags, pages, vmas, NULL);} EXPORT_SYMBOL(get_user_pages);
@@ -179,10 +172,7 @@ long get_user_pages_locked(unsigned long start, unsigned long nr_pages, unsigned int gup_flags, struct page **pages, int *locked) {
- int write = gup_flags & FOLL_WRITE;
- int force = gup_flags & FOLL_FORCE;
- return get_user_pages(start, nr_pages, write, force, pages, NULL);
- return get_user_pages(start, nr_pages, gup_flags, pages, NULL);
} EXPORT_SYMBOL(get_user_pages_locked);
-- 2.10.0
This patch removes the write and force parameters from get_user_pages_remote() and replaces them with a gup_flags parameter to make the use of FOLL_FORCE explicit in callers as use of this flag can result in surprising behaviour (and hence bugs) within the mm subsystem.
Signed-off-by: Lorenzo Stoakes lstoakes@gmail.com --- drivers/gpu/drm/etnaviv/etnaviv_gem.c | 7 +++++-- drivers/gpu/drm/i915/i915_gem_userptr.c | 6 +++++- drivers/infiniband/core/umem_odp.c | 7 +++++-- fs/exec.c | 9 +++++++-- include/linux/mm.h | 2 +- kernel/events/uprobes.c | 6 ++++-- mm/gup.c | 22 +++++++--------------- mm/memory.c | 6 +++++- security/tomoyo/domain.c | 2 +- 9 files changed, 40 insertions(+), 27 deletions(-)
diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c b/drivers/gpu/drm/etnaviv/etnaviv_gem.c index 5ce3603..0370b84 100644 --- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c +++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c @@ -748,19 +748,22 @@ static struct page **etnaviv_gem_userptr_do_get_pages( int ret = 0, pinned, npages = etnaviv_obj->base.size >> PAGE_SHIFT; struct page **pvec; uintptr_t ptr; + unsigned int flags = 0;
pvec = drm_malloc_ab(npages, sizeof(struct page *)); if (!pvec) return ERR_PTR(-ENOMEM);
+ if (!etnaviv_obj->userptr.ro) + flags |= FOLL_WRITE; + pinned = 0; ptr = etnaviv_obj->userptr.ptr;
down_read(&mm->mmap_sem); while (pinned < npages) { ret = get_user_pages_remote(task, mm, ptr, npages - pinned, - !etnaviv_obj->userptr.ro, 0, - pvec + pinned, NULL); + flags, pvec + pinned, NULL); if (ret < 0) break;
diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c index e537930..c6f780f 100644 --- a/drivers/gpu/drm/i915/i915_gem_userptr.c +++ b/drivers/gpu/drm/i915/i915_gem_userptr.c @@ -508,6 +508,10 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work) pvec = drm_malloc_gfp(npages, sizeof(struct page *), GFP_TEMPORARY); if (pvec != NULL) { struct mm_struct *mm = obj->userptr.mm->mm; + unsigned int flags = 0; + + if (!obj->userptr.read_only) + flags |= FOLL_WRITE;
ret = -EFAULT; if (atomic_inc_not_zero(&mm->mm_users)) { @@ -517,7 +521,7 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work) (work->task, mm, obj->userptr.ptr + pinned * PAGE_SIZE, npages - pinned, - !obj->userptr.read_only, 0, + flags, pvec + pinned, NULL); if (ret < 0) break; diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c index 75077a0..1f0fe32 100644 --- a/drivers/infiniband/core/umem_odp.c +++ b/drivers/infiniband/core/umem_odp.c @@ -527,6 +527,7 @@ int ib_umem_odp_map_dma_pages(struct ib_umem *umem, u64 user_virt, u64 bcnt, u64 off; int j, k, ret = 0, start_idx, npages = 0; u64 base_virt_addr; + unsigned int flags = 0;
if (access_mask == 0) return -EINVAL; @@ -556,6 +557,9 @@ int ib_umem_odp_map_dma_pages(struct ib_umem *umem, u64 user_virt, u64 bcnt, goto out_put_task; }
+ if (access_mask & ODP_WRITE_ALLOWED_BIT) + flags |= FOLL_WRITE; + start_idx = (user_virt - ib_umem_start(umem)) >> PAGE_SHIFT; k = start_idx;
@@ -574,8 +578,7 @@ int ib_umem_odp_map_dma_pages(struct ib_umem *umem, u64 user_virt, u64 bcnt, */ npages = get_user_pages_remote(owning_process, owning_mm, user_virt, gup_num_pages, - access_mask & ODP_WRITE_ALLOWED_BIT, - 0, local_page_list, NULL); + flags, local_page_list, NULL); up_read(&owning_mm->mmap_sem);
if (npages < 0) diff --git a/fs/exec.c b/fs/exec.c index 6fcfb3f..4e497b9 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -191,6 +191,7 @@ static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, { struct page *page; int ret; + unsigned int gup_flags = FOLL_FORCE;
#ifdef CONFIG_STACK_GROWSUP if (write) { @@ -199,12 +200,16 @@ static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, return NULL; } #endif + + if (write) + gup_flags |= FOLL_WRITE; + /* * We are doing an exec(). 'current' is the process * doing the exec and bprm->mm is the new process's mm. */ - ret = get_user_pages_remote(current, bprm->mm, pos, 1, write, - 1, &page, NULL); + ret = get_user_pages_remote(current, bprm->mm, pos, 1, gup_flags, + &page, NULL); if (ret <= 0) return NULL;
diff --git a/include/linux/mm.h b/include/linux/mm.h index 686a477..2a481d3 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1276,7 +1276,7 @@ long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, struct vm_area_struct **vmas, int *nonblocking); long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm, unsigned long start, unsigned long nr_pages, - int write, int force, struct page **pages, + unsigned int gup_flags, struct page **pages, struct vm_area_struct **vmas); long get_user_pages(unsigned long start, unsigned long nr_pages, unsigned int gup_flags, struct page **pages, diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index d4129bb..f9ec9ad 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -300,7 +300,8 @@ int uprobe_write_opcode(struct mm_struct *mm, unsigned long vaddr,
retry: /* Read the page with vaddr into memory */ - ret = get_user_pages_remote(NULL, mm, vaddr, 1, 0, 1, &old_page, &vma); + ret = get_user_pages_remote(NULL, mm, vaddr, 1, FOLL_FORCE, &old_page, + &vma); if (ret <= 0) return ret;
@@ -1710,7 +1711,8 @@ static int is_trap_at_addr(struct mm_struct *mm, unsigned long vaddr) * but we treat this as a 'remote' access since it is * essentially a kernel access to the memory. */ - result = get_user_pages_remote(NULL, mm, vaddr, 1, 0, 1, &page, NULL); + result = get_user_pages_remote(NULL, mm, vaddr, 1, FOLL_FORCE, &page, + NULL); if (result < 0) return result;
diff --git a/mm/gup.c b/mm/gup.c index dc91303..0deecf3 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -905,9 +905,7 @@ EXPORT_SYMBOL(get_user_pages_unlocked); * @mm: mm_struct of target mm * @start: starting user address * @nr_pages: number of pages from start to pin - * @write: whether pages will be written to by the caller - * @force: whether to force access even when user mapping is currently - * protected (but never forces write access to shared mapping). + * @gup_flags: flags modifying lookup behaviour * @pages: array that receives pointers to the pages pinned. * Should be at least nr_pages long. Or NULL, if caller * only intends to ensure the pages are faulted in. @@ -936,9 +934,9 @@ EXPORT_SYMBOL(get_user_pages_unlocked); * or similar operation cannot guarantee anything stronger anyway because * locks can't be held over the syscall boundary. * - * If write=0, the page must not be written to. If the page is written to, - * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called - * after the page is finished with, and before put_page is called. + * If gup_flags & FOLL_WRITE == 0, the page must not be written to. If the page + * is written to, set_page_dirty (or set_page_dirty_lock, as appropriate) must + * be called after the page is finished with, and before put_page is called. * * get_user_pages is typically used for fewer-copy IO operations, to get a * handle on the memory by some means other than accesses via the user virtual @@ -955,18 +953,12 @@ EXPORT_SYMBOL(get_user_pages_unlocked); */ long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm, unsigned long start, unsigned long nr_pages, - int write, int force, struct page **pages, + unsigned int gup_flags, struct page **pages, struct vm_area_struct **vmas) { - unsigned int flags = FOLL_TOUCH | FOLL_REMOTE; - - if (write) - flags |= FOLL_WRITE; - if (force) - flags |= FOLL_FORCE; - return __get_user_pages_locked(tsk, mm, start, nr_pages, pages, vmas, - NULL, false, flags); + NULL, false, + gup_flags | FOLL_TOUCH | FOLL_REMOTE); } EXPORT_SYMBOL(get_user_pages_remote);
diff --git a/mm/memory.c b/mm/memory.c index fc1987d..20a9adb 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3873,6 +3873,10 @@ static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, { struct vm_area_struct *vma; void *old_buf = buf; + unsigned int flags = FOLL_FORCE; + + if (write) + flags |= FOLL_WRITE;
down_read(&mm->mmap_sem); /* ignore errors, just check how much was successfully transferred */ @@ -3882,7 +3886,7 @@ static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, struct page *page = NULL;
ret = get_user_pages_remote(tsk, mm, addr, 1, - write, 1, &page, &vma); + flags, &page, &vma); if (ret <= 0) { #ifndef CONFIG_HAVE_IOREMAP_PROT break; diff --git a/security/tomoyo/domain.c b/security/tomoyo/domain.c index ade7c6c..682b73a 100644 --- a/security/tomoyo/domain.c +++ b/security/tomoyo/domain.c @@ -881,7 +881,7 @@ bool tomoyo_dump_page(struct linux_binprm *bprm, unsigned long pos, * the execve(). */ if (get_user_pages_remote(current, bprm->mm, pos, 1, - 0, 1, &page, NULL) <= 0) + FOLL_FORCE, &page, NULL) <= 0) return false; #else page = bprm->page[pos / PAGE_SIZE];
On Thu 13-10-16 01:20:17, Lorenzo Stoakes wrote:
This patch removes the write and force parameters from get_user_pages_remote() and replaces them with a gup_flags parameter to make the use of FOLL_FORCE explicit in callers as use of this flag can result in surprising behaviour (and hence bugs) within the mm subsystem.
Signed-off-by: Lorenzo Stoakes lstoakes@gmail.com
Looks good. You can add:
Reviewed-by: Jan Kara jack@suse.cz
Honza
drivers/gpu/drm/etnaviv/etnaviv_gem.c | 7 +++++-- drivers/gpu/drm/i915/i915_gem_userptr.c | 6 +++++- drivers/infiniband/core/umem_odp.c | 7 +++++-- fs/exec.c | 9 +++++++-- include/linux/mm.h | 2 +- kernel/events/uprobes.c | 6 ++++-- mm/gup.c | 22 +++++++--------------- mm/memory.c | 6 +++++- security/tomoyo/domain.c | 2 +- 9 files changed, 40 insertions(+), 27 deletions(-)
diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c b/drivers/gpu/drm/etnaviv/etnaviv_gem.c index 5ce3603..0370b84 100644 --- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c +++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c @@ -748,19 +748,22 @@ static struct page **etnaviv_gem_userptr_do_get_pages( int ret = 0, pinned, npages = etnaviv_obj->base.size >> PAGE_SHIFT; struct page **pvec; uintptr_t ptr;
unsigned int flags = 0;
pvec = drm_malloc_ab(npages, sizeof(struct page *)); if (!pvec) return ERR_PTR(-ENOMEM);
if (!etnaviv_obj->userptr.ro)
flags |= FOLL_WRITE;pinned = 0; ptr = etnaviv_obj->userptr.ptr;
down_read(&mm->mmap_sem); while (pinned < npages) { ret = get_user_pages_remote(task, mm, ptr, npages - pinned,
!etnaviv_obj->userptr.ro, 0,pvec + pinned, NULL);
flags, pvec + pinned, NULL);diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c index e537930..c6f780f 100644 --- a/drivers/gpu/drm/i915/i915_gem_userptr.c +++ b/drivers/gpu/drm/i915/i915_gem_userptr.c @@ -508,6 +508,10 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work) pvec = drm_malloc_gfp(npages, sizeof(struct page *), GFP_TEMPORARY); if (pvec != NULL) { struct mm_struct *mm = obj->userptr.mm->mm;
unsigned int flags = 0;if (!obj->userptr.read_only)flags |= FOLL_WRITE;ret = -EFAULT; if (atomic_inc_not_zero(&mm->mm_users)) {
@@ -517,7 +521,7 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work) (work->task, mm, obj->userptr.ptr + pinned * PAGE_SIZE, npages - pinned,
!obj->userptr.read_only, 0,
flags, pvec + pinned, NULL); if (ret < 0) break;diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c index 75077a0..1f0fe32 100644 --- a/drivers/infiniband/core/umem_odp.c +++ b/drivers/infiniband/core/umem_odp.c @@ -527,6 +527,7 @@ int ib_umem_odp_map_dma_pages(struct ib_umem *umem, u64 user_virt, u64 bcnt, u64 off; int j, k, ret = 0, start_idx, npages = 0; u64 base_virt_addr;
unsigned int flags = 0;
if (access_mask == 0) return -EINVAL;
@@ -556,6 +557,9 @@ int ib_umem_odp_map_dma_pages(struct ib_umem *umem, u64 user_virt, u64 bcnt, goto out_put_task; }
- if (access_mask & ODP_WRITE_ALLOWED_BIT)
flags |= FOLL_WRITE;- start_idx = (user_virt - ib_umem_start(umem)) >> PAGE_SHIFT; k = start_idx;
@@ -574,8 +578,7 @@ int ib_umem_odp_map_dma_pages(struct ib_umem *umem, u64 user_virt, u64 bcnt, */ npages = get_user_pages_remote(owning_process, owning_mm, user_virt, gup_num_pages,
access_mask & ODP_WRITE_ALLOWED_BIT,0, local_page_list, NULL);
flags, local_page_list, NULL);up_read(&owning_mm->mmap_sem);
if (npages < 0)
diff --git a/fs/exec.c b/fs/exec.c index 6fcfb3f..4e497b9 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -191,6 +191,7 @@ static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, { struct page *page; int ret;
- unsigned int gup_flags = FOLL_FORCE;
#ifdef CONFIG_STACK_GROWSUP if (write) { @@ -199,12 +200,16 @@ static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, return NULL; } #endif
- if (write)
gup_flags |= FOLL_WRITE;- /*
*/
- We are doing an exec(). 'current' is the process
- doing the exec and bprm->mm is the new process's mm.
- ret = get_user_pages_remote(current, bprm->mm, pos, 1, write,
1, &page, NULL);
- ret = get_user_pages_remote(current, bprm->mm, pos, 1, gup_flags,
&page, NULL);diff --git a/include/linux/mm.h b/include/linux/mm.h index 686a477..2a481d3 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1276,7 +1276,7 @@ long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, struct vm_area_struct **vmas, int *nonblocking); long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm, unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages,
unsigned int gup_flags, struct page **pages, struct vm_area_struct **vmas);long get_user_pages(unsigned long start, unsigned long nr_pages, unsigned int gup_flags, struct page **pages, diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index d4129bb..f9ec9ad 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -300,7 +300,8 @@ int uprobe_write_opcode(struct mm_struct *mm, unsigned long vaddr,
retry: /* Read the page with vaddr into memory */
- ret = get_user_pages_remote(NULL, mm, vaddr, 1, 0, 1, &old_page, &vma);
- ret = get_user_pages_remote(NULL, mm, vaddr, 1, FOLL_FORCE, &old_page,
&vma);@@ -1710,7 +1711,8 @@ static int is_trap_at_addr(struct mm_struct *mm, unsigned long vaddr) * but we treat this as a 'remote' access since it is * essentially a kernel access to the memory. */
- result = get_user_pages_remote(NULL, mm, vaddr, 1, 0, 1, &page, NULL);
- result = get_user_pages_remote(NULL, mm, vaddr, 1, FOLL_FORCE, &page,
NULL);diff --git a/mm/gup.c b/mm/gup.c index dc91303..0deecf3 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -905,9 +905,7 @@ EXPORT_SYMBOL(get_user_pages_unlocked);
- @mm: mm_struct of target mm
- @start: starting user address
- @nr_pages: number of pages from start to pin
- @write: whether pages will be written to by the caller
- @force: whether to force access even when user mapping is currently
protected (but never forces write access to shared mapping).
- @gup_flags: flags modifying lookup behaviour
- @pages: array that receives pointers to the pages pinned.
Should be at least nr_pages long. Or NULL, if calleronly intends to ensure the pages are faulted in.@@ -936,9 +934,9 @@ EXPORT_SYMBOL(get_user_pages_unlocked);
- or similar operation cannot guarantee anything stronger anyway because
- locks can't be held over the syscall boundary.
- If write=0, the page must not be written to. If the page is written to,
- set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
- after the page is finished with, and before put_page is called.
- If gup_flags & FOLL_WRITE == 0, the page must not be written to. If the page
- is written to, set_page_dirty (or set_page_dirty_lock, as appropriate) must
- be called after the page is finished with, and before put_page is called.
- get_user_pages is typically used for fewer-copy IO operations, to get a
- handle on the memory by some means other than accesses via the user virtual
@@ -955,18 +953,12 @@ EXPORT_SYMBOL(get_user_pages_unlocked); */ long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm, unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages,
unsigned int gup_flags, struct page **pages,{
- unsigned int flags = FOLL_TOUCH | FOLL_REMOTE;
- if (write)
flags |= FOLL_WRITE;- if (force)
flags |= FOLL_FORCE;- return __get_user_pages_locked(tsk, mm, start, nr_pages, pages, vmas,
NULL, false, flags);
NULL, false,gup_flags | FOLL_TOUCH | FOLL_REMOTE);} EXPORT_SYMBOL(get_user_pages_remote);
diff --git a/mm/memory.c b/mm/memory.c index fc1987d..20a9adb 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3873,6 +3873,10 @@ static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, { struct vm_area_struct *vma; void *old_buf = buf;
unsigned int flags = FOLL_FORCE;
if (write)
flags |= FOLL_WRITE;down_read(&mm->mmap_sem); /* ignore errors, just check how much was successfully transferred */
@@ -3882,7 +3886,7 @@ static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, struct page *page = NULL;
ret = get_user_pages_remote(tsk, mm, addr, 1,
write, 1, &page, &vma);
flags, &page, &vma);#ifndef CONFIG_HAVE_IOREMAP_PROT break; diff --git a/security/tomoyo/domain.c b/security/tomoyo/domain.c index ade7c6c..682b73a 100644 --- a/security/tomoyo/domain.c +++ b/security/tomoyo/domain.c @@ -881,7 +881,7 @@ bool tomoyo_dump_page(struct linux_binprm *bprm, unsigned long pos, * the execve(). */ if (get_user_pages_remote(current, bprm->mm, pos, 1,
0, 1, &page, NULL) <= 0)
FOLL_FORCE, &page, NULL) <= 0)#else page = bprm->page[pos / PAGE_SIZE]; -- 2.10.0
This patch removes the write parameter from __access_remote_vm() and replaces it with a gup_flags parameter as use of this function previously _implied_ FOLL_FORCE, whereas after this patch callers explicitly pass this flag.
We make this explicit as use of FOLL_FORCE can result in surprising behaviour (and hence bugs) within the mm subsystem.
Signed-off-by: Lorenzo Stoakes lstoakes@gmail.com --- mm/memory.c | 23 +++++++++++++++-------- mm/nommu.c | 9 ++++++--- 2 files changed, 21 insertions(+), 11 deletions(-)
diff --git a/mm/memory.c b/mm/memory.c index 20a9adb..79ebed3 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3869,14 +3869,11 @@ EXPORT_SYMBOL_GPL(generic_access_phys); * given task for page fault accounting. */ static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, - unsigned long addr, void *buf, int len, int write) + unsigned long addr, void *buf, int len, unsigned int gup_flags) { struct vm_area_struct *vma; void *old_buf = buf; - unsigned int flags = FOLL_FORCE; - - if (write) - flags |= FOLL_WRITE; + int write = gup_flags & FOLL_WRITE;
down_read(&mm->mmap_sem); /* ignore errors, just check how much was successfully transferred */ @@ -3886,7 +3883,7 @@ static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, struct page *page = NULL;
ret = get_user_pages_remote(tsk, mm, addr, 1, - flags, &page, &vma); + gup_flags, &page, &vma); if (ret <= 0) { #ifndef CONFIG_HAVE_IOREMAP_PROT break; @@ -3945,7 +3942,12 @@ static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, int access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf, int len, int write) { - return __access_remote_vm(NULL, mm, addr, buf, len, write); + unsigned int flags = FOLL_FORCE; + + if (write) + flags |= FOLL_WRITE; + + return __access_remote_vm(NULL, mm, addr, buf, len, flags); }
/* @@ -3958,12 +3960,17 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr, { struct mm_struct *mm; int ret; + unsigned int flags = FOLL_FORCE;
mm = get_task_mm(tsk); if (!mm) return 0;
- ret = __access_remote_vm(tsk, mm, addr, buf, len, write); + if (write) + flags |= FOLL_WRITE; + + ret = __access_remote_vm(tsk, mm, addr, buf, len, flags); + mmput(mm);
return ret; diff --git a/mm/nommu.c b/mm/nommu.c index 70cb844..bde7df3 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -1809,9 +1809,10 @@ void filemap_map_pages(struct fault_env *fe, EXPORT_SYMBOL(filemap_map_pages);
static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, - unsigned long addr, void *buf, int len, int write) + unsigned long addr, void *buf, int len, unsigned int gup_flags) { struct vm_area_struct *vma; + int write = gup_flags & FOLL_WRITE;
down_read(&mm->mmap_sem);
@@ -1853,7 +1854,8 @@ static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, int access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf, int len, int write) { - return __access_remote_vm(NULL, mm, addr, buf, len, write); + return __access_remote_vm(NULL, mm, addr, buf, len, + write ? FOLL_WRITE : 0); }
/* @@ -1871,7 +1873,8 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, in if (!mm) return 0;
- len = __access_remote_vm(tsk, mm, addr, buf, len, write); + len = __access_remote_vm(tsk, mm, addr, buf, len, + write ? FOLL_WRITE : 0);
mmput(mm); return len;
On Thu 13-10-16 01:20:18, Lorenzo Stoakes wrote:
This patch removes the write parameter from __access_remote_vm() and replaces it with a gup_flags parameter as use of this function previously _implied_ FOLL_FORCE, whereas after this patch callers explicitly pass this flag.
We make this explicit as use of FOLL_FORCE can result in surprising behaviour (and hence bugs) within the mm subsystem.
Signed-off-by: Lorenzo Stoakes lstoakes@gmail.com
So I'm not convinced this (and the following two patches) is actually helping much. By grepping for FOLL_FORCE we will easily see that any caller of access_remote_vm() gets that semantics and can thus continue search accordingly (it is much simpler than searching for all get_user_pages() users and extracting from parameter lists what they actually pass as 'force' argument). Sure it makes somewhat more visible to callers of access_remote_vm() that they get FOLL_FORCE semantics but OTOH it also opens a space for issues where a caller of access_remote_vm() actually wants FOLL_FORCE (and currently all of them want it) and just mistakenly does not set it. All in all I'd prefer to keep access_remote_vm() and friends as is...
Honza
mm/memory.c | 23 +++++++++++++++-------- mm/nommu.c | 9 ++++++--- 2 files changed, 21 insertions(+), 11 deletions(-)
diff --git a/mm/memory.c b/mm/memory.c index 20a9adb..79ebed3 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3869,14 +3869,11 @@ EXPORT_SYMBOL_GPL(generic_access_phys);
- given task for page fault accounting.
*/ static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
unsigned long addr, void *buf, int len, int write)
unsigned long addr, void *buf, int len, unsigned int gup_flags){ struct vm_area_struct *vma; void *old_buf = buf;
- unsigned int flags = FOLL_FORCE;
- if (write)
flags |= FOLL_WRITE;
int write = gup_flags & FOLL_WRITE;
down_read(&mm->mmap_sem); /* ignore errors, just check how much was successfully transferred */
@@ -3886,7 +3883,7 @@ static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, struct page *page = NULL;
ret = get_user_pages_remote(tsk, mm, addr, 1,
flags, &page, &vma);
gup_flags, &page, &vma);#ifndef CONFIG_HAVE_IOREMAP_PROT break; @@ -3945,7 +3942,12 @@ static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, int access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf, int len, int write) {
- return __access_remote_vm(NULL, mm, addr, buf, len, write);
- unsigned int flags = FOLL_FORCE;
- if (write)
flags |= FOLL_WRITE;- return __access_remote_vm(NULL, mm, addr, buf, len, flags);
}
/* @@ -3958,12 +3960,17 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr, { struct mm_struct *mm; int ret;
unsigned int flags = FOLL_FORCE;
mm = get_task_mm(tsk); if (!mm) return 0;
- ret = __access_remote_vm(tsk, mm, addr, buf, len, write);
if (write)
flags |= FOLL_WRITE;ret = __access_remote_vm(tsk, mm, addr, buf, len, flags);
mmput(mm);
return ret;
diff --git a/mm/nommu.c b/mm/nommu.c index 70cb844..bde7df3 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -1809,9 +1809,10 @@ void filemap_map_pages(struct fault_env *fe, EXPORT_SYMBOL(filemap_map_pages);
static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
unsigned long addr, void *buf, int len, int write)
unsigned long addr, void *buf, int len, unsigned int gup_flags){ struct vm_area_struct *vma;
int write = gup_flags & FOLL_WRITE;
down_read(&mm->mmap_sem);
@@ -1853,7 +1854,8 @@ static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, int access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf, int len, int write) {
- return __access_remote_vm(NULL, mm, addr, buf, len, write);
- return __access_remote_vm(NULL, mm, addr, buf, len,
write ? FOLL_WRITE : 0);}
/* @@ -1871,7 +1873,8 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, in if (!mm) return 0;
- len = __access_remote_vm(tsk, mm, addr, buf, len, write);
len = __access_remote_vm(tsk, mm, addr, buf, len,
write ? FOLL_WRITE : 0);mmput(mm); return len;
-- 2.10.0
On Wed 19-10-16 09:59:03, Jan Kara wrote:
On Thu 13-10-16 01:20:18, Lorenzo Stoakes wrote:
This patch removes the write parameter from __access_remote_vm() and replaces it with a gup_flags parameter as use of this function previously _implied_ FOLL_FORCE, whereas after this patch callers explicitly pass this flag.
We make this explicit as use of FOLL_FORCE can result in surprising behaviour (and hence bugs) within the mm subsystem.
Signed-off-by: Lorenzo Stoakes lstoakes@gmail.com
So I'm not convinced this (and the following two patches) is actually helping much. By grepping for FOLL_FORCE we will easily see that any caller of access_remote_vm() gets that semantics and can thus continue search
I am really wondering. Is there anything inherent that would require FOLL_FORCE for access_remote_vm? I mean FOLL_FORCE is a really non-trivial thing. It doesn't obey vma permissions so we should really minimize its usage. Do all of those users really need FOLL_FORCE?
Anyway I would rather see the flag explicit and used at more places than hidden behind a helper function.
On Wed, Oct 19, 2016 at 10:13:52AM +0200, Michal Hocko wrote:
On Wed 19-10-16 09:59:03, Jan Kara wrote:
On Thu 13-10-16 01:20:18, Lorenzo Stoakes wrote:
This patch removes the write parameter from __access_remote_vm() and replaces it with a gup_flags parameter as use of this function previously _implied_ FOLL_FORCE, whereas after this patch callers explicitly pass this flag.
We make this explicit as use of FOLL_FORCE can result in surprising behaviour (and hence bugs) within the mm subsystem.
Signed-off-by: Lorenzo Stoakes lstoakes@gmail.com
So I'm not convinced this (and the following two patches) is actually helping much. By grepping for FOLL_FORCE we will easily see that any caller of access_remote_vm() gets that semantics and can thus continue search
I am really wondering. Is there anything inherent that would require FOLL_FORCE for access_remote_vm? I mean FOLL_FORCE is a really non-trivial thing. It doesn't obey vma permissions so we should really minimize its usage. Do all of those users really need FOLL_FORCE?
I wonder about this also, for example by accessing /proc/self/mem you trigger access_remote_vm() and consequently get_user_pages_remote() meaning FOLL_FORCE is implied and you can use /proc/self/mem to override any VMA permissions. I wonder if this is desirable behaviour or whether this ought to be limited to ptrace system calls. Regardless, by making the flag more visible it makes it easier to see that this is happening.
Note that this /proc/self/mem behaviour is what triggered the bug that brought about this discussion in the first place - https://marc.info/?l=linux-mm&m=147363447105059 - as using /proc/self/mem this way on PROT_NONE memory broke some assumptions.
On the other hand I see your point Jan in that you know any caller of these functions will have FOLL_FORCE implied, and you have to decide to stop passing the flag at _some_ point in the stack, however it seems fairly sane to have that stopping point exist outside of exported gup functions so the gup interface forces explicitness but callers can wrap things as they need.
On Wed 19-10-16 09:40:45, Lorenzo Stoakes wrote:
On Wed, Oct 19, 2016 at 10:13:52AM +0200, Michal Hocko wrote:
On Wed 19-10-16 09:59:03, Jan Kara wrote:
On Thu 13-10-16 01:20:18, Lorenzo Stoakes wrote:
This patch removes the write parameter from __access_remote_vm() and replaces it with a gup_flags parameter as use of this function previously _implied_ FOLL_FORCE, whereas after this patch callers explicitly pass this flag.
We make this explicit as use of FOLL_FORCE can result in surprising behaviour (and hence bugs) within the mm subsystem.
Signed-off-by: Lorenzo Stoakes lstoakes@gmail.com
So I'm not convinced this (and the following two patches) is actually helping much. By grepping for FOLL_FORCE we will easily see that any caller of access_remote_vm() gets that semantics and can thus continue search
I am really wondering. Is there anything inherent that would require FOLL_FORCE for access_remote_vm? I mean FOLL_FORCE is a really non-trivial thing. It doesn't obey vma permissions so we should really minimize its usage. Do all of those users really need FOLL_FORCE?
I wonder about this also, for example by accessing /proc/self/mem you trigger access_remote_vm() and consequently get_user_pages_remote() meaning FOLL_FORCE is implied and you can use /proc/self/mem to override any VMA permissions. I
yes this is the desirable and expected behavior.
wonder if this is desirable behaviour or whether this ought to be limited to ptrace system calls. Regardless, by making the flag more visible it makes it easier to see that this is happening.
mem_open already enforces PTRACE_MODE_ATTACH
On Wed, Oct 19, 2016 at 10:52:05AM +0200, Michal Hocko wrote:
yes this is the desirable and expected behavior.
wonder if this is desirable behaviour or whether this ought to be limited to ptrace system calls. Regardless, by making the flag more visible it makes it easier to see that this is happening.
mem_open already enforces PTRACE_MODE_ATTACH
Ah I missed this, that makes a lot of sense, thanks!
I still wonder whether other invocations of access_remote_vm() in fs/proc/base.c (the principle caller of this function) need FOLL_FORCE, for example the various calls that simply read data from other processes, so I think the point stands about keeping this explicit.
On Wed 19-10-16 10:06:46, Lorenzo Stoakes wrote:
On Wed, Oct 19, 2016 at 10:52:05AM +0200, Michal Hocko wrote:
yes this is the desirable and expected behavior.
wonder if this is desirable behaviour or whether this ought to be limited to ptrace system calls. Regardless, by making the flag more visible it makes it easier to see that this is happening.
mem_open already enforces PTRACE_MODE_ATTACH
Ah I missed this, that makes a lot of sense, thanks!
I still wonder whether other invocations of access_remote_vm() in fs/proc/base.c (the principle caller of this function) need FOLL_FORCE, for example the various calls that simply read data from other processes, so I think the point stands about keeping this explicit.
I do agree. Making them explicit will help to clean them up later, should there be a need.
This patch removes the write parameter from access_remote_vm() and replaces it with a gup_flags parameter as use of this function previously _implied_ FOLL_FORCE, whereas after this patch callers explicitly pass this flag.
We make this explicit as use of FOLL_FORCE can result in surprising behaviour (and hence bugs) within the mm subsystem.
Signed-off-by: Lorenzo Stoakes lstoakes@gmail.com --- fs/proc/base.c | 19 +++++++++++++------ include/linux/mm.h | 2 +- mm/memory.c | 11 +++-------- mm/nommu.c | 7 +++---- 4 files changed, 20 insertions(+), 19 deletions(-)
diff --git a/fs/proc/base.c b/fs/proc/base.c index c2964d8..8e65446 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -252,7 +252,7 @@ static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf, * Inherently racy -- command line shares address space * with code and data. */ - rv = access_remote_vm(mm, arg_end - 1, &c, 1, 0); + rv = access_remote_vm(mm, arg_end - 1, &c, 1, FOLL_FORCE); if (rv <= 0) goto out_free_page;
@@ -270,7 +270,8 @@ static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf, int nr_read;
_count = min3(count, len, PAGE_SIZE); - nr_read = access_remote_vm(mm, p, page, _count, 0); + nr_read = access_remote_vm(mm, p, page, _count, + FOLL_FORCE); if (nr_read < 0) rv = nr_read; if (nr_read <= 0) @@ -305,7 +306,8 @@ static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf, bool final;
_count = min3(count, len, PAGE_SIZE); - nr_read = access_remote_vm(mm, p, page, _count, 0); + nr_read = access_remote_vm(mm, p, page, _count, + FOLL_FORCE); if (nr_read < 0) rv = nr_read; if (nr_read <= 0) @@ -354,7 +356,8 @@ static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf, bool final;
_count = min3(count, len, PAGE_SIZE); - nr_read = access_remote_vm(mm, p, page, _count, 0); + nr_read = access_remote_vm(mm, p, page, _count, + FOLL_FORCE); if (nr_read < 0) rv = nr_read; if (nr_read <= 0) @@ -832,6 +835,7 @@ static ssize_t mem_rw(struct file *file, char __user *buf, unsigned long addr = *ppos; ssize_t copied; char *page; + unsigned int flags = FOLL_FORCE;
if (!mm) return 0; @@ -844,6 +848,9 @@ static ssize_t mem_rw(struct file *file, char __user *buf, if (!atomic_inc_not_zero(&mm->mm_users)) goto free;
+ if (write) + flags |= FOLL_WRITE; + while (count > 0) { int this_len = min_t(int, count, PAGE_SIZE);
@@ -852,7 +859,7 @@ static ssize_t mem_rw(struct file *file, char __user *buf, break; }
- this_len = access_remote_vm(mm, addr, page, this_len, write); + this_len = access_remote_vm(mm, addr, page, this_len, flags); if (!this_len) { if (!copied) copied = -EIO; @@ -965,7 +972,7 @@ static ssize_t environ_read(struct file *file, char __user *buf, this_len = min(max_len, this_len);
retval = access_remote_vm(mm, (env_start + src), - page, this_len, 0); + page, this_len, FOLL_FORCE);
if (retval <= 0) { ret = retval; diff --git a/include/linux/mm.h b/include/linux/mm.h index 2a481d3..3e5234e 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1268,7 +1268,7 @@ static inline int fixup_user_fault(struct task_struct *tsk,
extern int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write); extern int access_remote_vm(struct mm_struct *mm, unsigned long addr, - void *buf, int len, int write); + void *buf, int len, unsigned int gup_flags);
long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, unsigned long start, unsigned long nr_pages, diff --git a/mm/memory.c b/mm/memory.c index 79ebed3..bac2d99 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3935,19 +3935,14 @@ static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, * @addr: start address to access * @buf: source or destination buffer * @len: number of bytes to transfer - * @write: whether the access is a write + * @gup_flags: flags modifying lookup behaviour * * The caller must hold a reference on @mm. */ int access_remote_vm(struct mm_struct *mm, unsigned long addr, - void *buf, int len, int write) + void *buf, int len, unsigned int gup_flags) { - unsigned int flags = FOLL_FORCE; - - if (write) - flags |= FOLL_WRITE; - - return __access_remote_vm(NULL, mm, addr, buf, len, flags); + return __access_remote_vm(NULL, mm, addr, buf, len, gup_flags); }
/* diff --git a/mm/nommu.c b/mm/nommu.c index bde7df3..93d5bb5 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -1847,15 +1847,14 @@ static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, * @addr: start address to access * @buf: source or destination buffer * @len: number of bytes to transfer - * @write: whether the access is a write + * @gup_flags: flags modifying lookup behaviour * * The caller must hold a reference on @mm. */ int access_remote_vm(struct mm_struct *mm, unsigned long addr, - void *buf, int len, int write) + void *buf, int len, unsigned int gup_flags) { - return __access_remote_vm(NULL, mm, addr, buf, len, - write ? FOLL_WRITE : 0); + return __access_remote_vm(NULL, mm, addr, buf, len, gup_flags); }
/*
This patch removes the write parameter from access_process_vm() and replaces it with a gup_flags parameter as use of this function previously _implied_ FOLL_FORCE, whereas after this patch callers explicitly pass this flag.
We make this explicit as use of FOLL_FORCE can result in surprising behaviour (and hence bugs) within the mm subsystem.
Signed-off-by: Lorenzo Stoakes lstoakes@gmail.com --- arch/alpha/kernel/ptrace.c | 9 ++++++--- arch/blackfin/kernel/ptrace.c | 5 +++-- arch/cris/arch-v32/kernel/ptrace.c | 4 ++-- arch/ia64/kernel/ptrace.c | 14 +++++++++----- arch/m32r/kernel/ptrace.c | 15 ++++++++++----- arch/mips/kernel/ptrace32.c | 5 +++-- arch/powerpc/kernel/ptrace32.c | 5 +++-- arch/score/kernel/ptrace.c | 10 ++++++---- arch/sparc/kernel/ptrace_64.c | 24 ++++++++++++++++-------- arch/x86/kernel/step.c | 3 ++- arch/x86/um/ptrace_32.c | 3 ++- arch/x86/um/ptrace_64.c | 3 ++- include/linux/mm.h | 3 ++- kernel/ptrace.c | 16 ++++++++++------ mm/memory.c | 8 ++------ mm/nommu.c | 6 +++--- mm/util.c | 5 +++-- 17 files changed, 84 insertions(+), 54 deletions(-)
diff --git a/arch/alpha/kernel/ptrace.c b/arch/alpha/kernel/ptrace.c index d9ee817..940dfb4 100644 --- a/arch/alpha/kernel/ptrace.c +++ b/arch/alpha/kernel/ptrace.c @@ -157,14 +157,16 @@ put_reg(struct task_struct *task, unsigned long regno, unsigned long data) static inline int read_int(struct task_struct *task, unsigned long addr, int * data) { - int copied = access_process_vm(task, addr, data, sizeof(int), 0); + int copied = access_process_vm(task, addr, data, sizeof(int), + FOLL_FORCE); return (copied == sizeof(int)) ? 0 : -EIO; }
static inline int write_int(struct task_struct *task, unsigned long addr, int data) { - int copied = access_process_vm(task, addr, &data, sizeof(int), 1); + int copied = access_process_vm(task, addr, &data, sizeof(int), + FOLL_FORCE | FOLL_WRITE); return (copied == sizeof(int)) ? 0 : -EIO; }
@@ -281,7 +283,8 @@ long arch_ptrace(struct task_struct *child, long request, /* When I and D space are separate, these will need to be fixed. */ case PTRACE_PEEKTEXT: /* read word at location addr. */ case PTRACE_PEEKDATA: - copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0); + copied = access_process_vm(child, addr, &tmp, sizeof(tmp), + FOLL_FORCE); ret = -EIO; if (copied != sizeof(tmp)) break; diff --git a/arch/blackfin/kernel/ptrace.c b/arch/blackfin/kernel/ptrace.c index 8b8fe67..8d79286 100644 --- a/arch/blackfin/kernel/ptrace.c +++ b/arch/blackfin/kernel/ptrace.c @@ -271,7 +271,7 @@ long arch_ptrace(struct task_struct *child, long request, case BFIN_MEM_ACCESS_CORE: case BFIN_MEM_ACCESS_CORE_ONLY: copied = access_process_vm(child, addr, &tmp, - to_copy, 0); + to_copy, FOLL_FORCE); if (copied) break;
@@ -324,7 +324,8 @@ long arch_ptrace(struct task_struct *child, long request, case BFIN_MEM_ACCESS_CORE: case BFIN_MEM_ACCESS_CORE_ONLY: copied = access_process_vm(child, addr, &data, - to_copy, 1); + to_copy, + FOLL_FORCE | FOLL_WRITE); break; case BFIN_MEM_ACCESS_DMA: if (safe_dma_memcpy(paddr, &data, to_copy)) diff --git a/arch/cris/arch-v32/kernel/ptrace.c b/arch/cris/arch-v32/kernel/ptrace.c index f085229..f0df654 100644 --- a/arch/cris/arch-v32/kernel/ptrace.c +++ b/arch/cris/arch-v32/kernel/ptrace.c @@ -147,7 +147,7 @@ long arch_ptrace(struct task_struct *child, long request, /* The trampoline page is globally mapped, no page table to traverse.*/ tmp = *(unsigned long*)addr; } else { - copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0); + copied = access_process_vm(child, addr, &tmp, sizeof(tmp), FOLL_FORCE);
if (copied != sizeof(tmp)) break; @@ -279,7 +279,7 @@ static int insn_size(struct task_struct *child, unsigned long pc) int opsize = 0;
/* Read the opcode at pc (do what PTRACE_PEEKTEXT would do). */ - copied = access_process_vm(child, pc, &opcode, sizeof(opcode), 0); + copied = access_process_vm(child, pc, &opcode, sizeof(opcode), FOLL_FORCE); if (copied != sizeof(opcode)) return 0;
diff --git a/arch/ia64/kernel/ptrace.c b/arch/ia64/kernel/ptrace.c index 6f54d51..31aa8c0 100644 --- a/arch/ia64/kernel/ptrace.c +++ b/arch/ia64/kernel/ptrace.c @@ -453,7 +453,7 @@ ia64_peek (struct task_struct *child, struct switch_stack *child_stack, return 0; } } - copied = access_process_vm(child, addr, &ret, sizeof(ret), 0); + copied = access_process_vm(child, addr, &ret, sizeof(ret), FOLL_FORCE); if (copied != sizeof(ret)) return -EIO; *val = ret; @@ -489,7 +489,8 @@ ia64_poke (struct task_struct *child, struct switch_stack *child_stack, *ia64_rse_skip_regs(krbs, regnum) = val; } } - } else if (access_process_vm(child, addr, &val, sizeof(val), 1) + } else if (access_process_vm(child, addr, &val, sizeof(val), + FOLL_FORCE | FOLL_WRITE) != sizeof(val)) return -EIO; return 0; @@ -543,7 +544,8 @@ ia64_sync_user_rbs (struct task_struct *child, struct switch_stack *sw, ret = ia64_peek(child, sw, user_rbs_end, addr, &val); if (ret < 0) return ret; - if (access_process_vm(child, addr, &val, sizeof(val), 1) + if (access_process_vm(child, addr, &val, sizeof(val), + FOLL_FORCE | FOLL_WRITE) != sizeof(val)) return -EIO; } @@ -559,7 +561,8 @@ ia64_sync_kernel_rbs (struct task_struct *child, struct switch_stack *sw,
/* now copy word for word from user rbs to kernel rbs: */ for (addr = user_rbs_start; addr < user_rbs_end; addr += 8) { - if (access_process_vm(child, addr, &val, sizeof(val), 0) + if (access_process_vm(child, addr, &val, sizeof(val), + FOLL_FORCE) != sizeof(val)) return -EIO;
@@ -1156,7 +1159,8 @@ arch_ptrace (struct task_struct *child, long request, case PTRACE_PEEKTEXT: case PTRACE_PEEKDATA: /* read word at location addr */ - if (access_process_vm(child, addr, &data, sizeof(data), 0) + if (access_process_vm(child, addr, &data, sizeof(data), + FOLL_FORCE) != sizeof(data)) return -EIO; /* ensure return value is not mistaken for error code */ diff --git a/arch/m32r/kernel/ptrace.c b/arch/m32r/kernel/ptrace.c index 51f5e9a..c145605 100644 --- a/arch/m32r/kernel/ptrace.c +++ b/arch/m32r/kernel/ptrace.c @@ -493,7 +493,8 @@ unregister_all_debug_traps(struct task_struct *child) int i;
for (i = 0; i < p->nr_trap; i++) - access_process_vm(child, p->addr[i], &p->insn[i], sizeof(p->insn[i]), 1); + access_process_vm(child, p->addr[i], &p->insn[i], sizeof(p->insn[i]), + FOLL_FORCE | FOLL_WRITE); p->nr_trap = 0; }
@@ -537,7 +538,8 @@ embed_debug_trap(struct task_struct *child, unsigned long next_pc) unsigned long next_insn, code; unsigned long addr = next_pc & ~3;
- if (access_process_vm(child, addr, &next_insn, sizeof(next_insn), 0) + if (access_process_vm(child, addr, &next_insn, sizeof(next_insn), + FOLL_FORCE) != sizeof(next_insn)) { return -1; /* error */ } @@ -546,7 +548,8 @@ embed_debug_trap(struct task_struct *child, unsigned long next_pc) if (register_debug_trap(child, next_pc, next_insn, &code)) { return -1; /* error */ } - if (access_process_vm(child, addr, &code, sizeof(code), 1) + if (access_process_vm(child, addr, &code, sizeof(code), + FOLL_FORCE | FOLL_WRITE) != sizeof(code)) { return -1; /* error */ } @@ -562,7 +565,8 @@ withdraw_debug_trap(struct pt_regs *regs) addr = (regs->bpc - 2) & ~3; regs->bpc -= 2; if (unregister_debug_trap(current, addr, &code)) { - access_process_vm(current, addr, &code, sizeof(code), 1); + access_process_vm(current, addr, &code, sizeof(code), + FOLL_FORCE | FOLL_WRITE); invalidate_cache(); } } @@ -589,7 +593,8 @@ void user_enable_single_step(struct task_struct *child) /* Compute next pc. */ pc = get_stack_long(child, PT_BPC);
- if (access_process_vm(child, pc&~3, &insn, sizeof(insn), 0) + if (access_process_vm(child, pc&~3, &insn, sizeof(insn), + FOLL_FORCE) != sizeof(insn)) return;
diff --git a/arch/mips/kernel/ptrace32.c b/arch/mips/kernel/ptrace32.c index 283b5a1..7e71a4e 100644 --- a/arch/mips/kernel/ptrace32.c +++ b/arch/mips/kernel/ptrace32.c @@ -70,7 +70,7 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request, break;
copied = access_process_vm(child, (u64)addrOthers, &tmp, - sizeof(tmp), 0); + sizeof(tmp), FOLL_FORCE); if (copied != sizeof(tmp)) break; ret = put_user(tmp, (u32 __user *) (unsigned long) data); @@ -179,7 +179,8 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request, break; ret = 0; if (access_process_vm(child, (u64)addrOthers, &data, - sizeof(data), 1) == sizeof(data)) + sizeof(data), + FOLL_FORCE | FOLL_WRITE) == sizeof(data)) break; ret = -EIO; break; diff --git a/arch/powerpc/kernel/ptrace32.c b/arch/powerpc/kernel/ptrace32.c index f52b7db3..010b7b3 100644 --- a/arch/powerpc/kernel/ptrace32.c +++ b/arch/powerpc/kernel/ptrace32.c @@ -74,7 +74,7 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request, break;
copied = access_process_vm(child, (u64)addrOthers, &tmp, - sizeof(tmp), 0); + sizeof(tmp), FOLL_FORCE); if (copied != sizeof(tmp)) break; ret = put_user(tmp, (u32 __user *)data); @@ -179,7 +179,8 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request, break; ret = 0; if (access_process_vm(child, (u64)addrOthers, &tmp, - sizeof(tmp), 1) == sizeof(tmp)) + sizeof(tmp), + FOLL_FORCE | FOLL_WRITE) == sizeof(tmp)) break; ret = -EIO; break; diff --git a/arch/score/kernel/ptrace.c b/arch/score/kernel/ptrace.c index 5583618..4f7314d 100644 --- a/arch/score/kernel/ptrace.c +++ b/arch/score/kernel/ptrace.c @@ -131,7 +131,7 @@ read_tsk_long(struct task_struct *child, { int copied;
- copied = access_process_vm(child, addr, res, sizeof(*res), 0); + copied = access_process_vm(child, addr, res, sizeof(*res), FOLL_FORCE);
return copied != sizeof(*res) ? -EIO : 0; } @@ -142,7 +142,7 @@ read_tsk_short(struct task_struct *child, { int copied;
- copied = access_process_vm(child, addr, res, sizeof(*res), 0); + copied = access_process_vm(child, addr, res, sizeof(*res), FOLL_FORCE);
return copied != sizeof(*res) ? -EIO : 0; } @@ -153,7 +153,8 @@ write_tsk_short(struct task_struct *child, { int copied;
- copied = access_process_vm(child, addr, &val, sizeof(val), 1); + copied = access_process_vm(child, addr, &val, sizeof(val), + FOLL_FORCE | FOLL_WRITE);
return copied != sizeof(val) ? -EIO : 0; } @@ -164,7 +165,8 @@ write_tsk_long(struct task_struct *child, { int copied;
- copied = access_process_vm(child, addr, &val, sizeof(val), 1); + copied = access_process_vm(child, addr, &val, sizeof(val), + FOLL_FORCE | FOLL_WRITE);
return copied != sizeof(val) ? -EIO : 0; } diff --git a/arch/sparc/kernel/ptrace_64.c b/arch/sparc/kernel/ptrace_64.c index 9ddc492..ac082dd 100644 --- a/arch/sparc/kernel/ptrace_64.c +++ b/arch/sparc/kernel/ptrace_64.c @@ -127,7 +127,8 @@ static int get_from_target(struct task_struct *target, unsigned long uaddr, if (copy_from_user(kbuf, (void __user *) uaddr, len)) return -EFAULT; } else { - int len2 = access_process_vm(target, uaddr, kbuf, len, 0); + int len2 = access_process_vm(target, uaddr, kbuf, len, + FOLL_FORCE); if (len2 != len) return -EFAULT; } @@ -141,7 +142,8 @@ static int set_to_target(struct task_struct *target, unsigned long uaddr, if (copy_to_user((void __user *) uaddr, kbuf, len)) return -EFAULT; } else { - int len2 = access_process_vm(target, uaddr, kbuf, len, 1); + int len2 = access_process_vm(target, uaddr, kbuf, len, + FOLL_FORCE | FOLL_WRITE); if (len2 != len) return -EFAULT; } @@ -505,7 +507,8 @@ static int genregs32_get(struct task_struct *target, if (access_process_vm(target, (unsigned long) ®_window[pos], - k, sizeof(*k), 0) + k, sizeof(*k), + FOLL_FORCE) != sizeof(*k)) return -EFAULT; k++; @@ -531,12 +534,14 @@ static int genregs32_get(struct task_struct *target, if (access_process_vm(target, (unsigned long) ®_window[pos], - ®, sizeof(reg), 0) + ®, sizeof(reg), + FOLL_FORCE) != sizeof(reg)) return -EFAULT; if (access_process_vm(target, (unsigned long) u, - ®, sizeof(reg), 1) + ®, sizeof(reg), + FOLL_FORCE | FOLL_WRITE) != sizeof(reg)) return -EFAULT; pos++; @@ -615,7 +620,8 @@ static int genregs32_set(struct task_struct *target, (unsigned long) ®_window[pos], (void *) k, - sizeof(*k), 1) + sizeof(*k), + FOLL_FORCE | FOLL_WRITE) != sizeof(*k)) return -EFAULT; k++; @@ -642,13 +648,15 @@ static int genregs32_set(struct task_struct *target, if (access_process_vm(target, (unsigned long) u, - ®, sizeof(reg), 0) + ®, sizeof(reg), + FOLL_FORCE) != sizeof(reg)) return -EFAULT; if (access_process_vm(target, (unsigned long) ®_window[pos], - ®, sizeof(reg), 1) + ®, sizeof(reg), + FOLL_FORCE | FOLL_WRITE) != sizeof(reg)) return -EFAULT; pos++; diff --git a/arch/x86/kernel/step.c b/arch/x86/kernel/step.c index c9a0738..a23ce84 100644 --- a/arch/x86/kernel/step.c +++ b/arch/x86/kernel/step.c @@ -57,7 +57,8 @@ static int is_setting_trap_flag(struct task_struct *child, struct pt_regs *regs) unsigned char opcode[15]; unsigned long addr = convert_ip_to_linear(child, regs);
- copied = access_process_vm(child, addr, opcode, sizeof(opcode), 0); + copied = access_process_vm(child, addr, opcode, sizeof(opcode), + FOLL_FORCE); for (i = 0; i < copied; i++) { switch (opcode[i]) { /* popf and iret */ diff --git a/arch/x86/um/ptrace_32.c b/arch/x86/um/ptrace_32.c index 5766ead..60a5a5a 100644 --- a/arch/x86/um/ptrace_32.c +++ b/arch/x86/um/ptrace_32.c @@ -36,7 +36,8 @@ int is_syscall(unsigned long addr) * slow, but that doesn't matter, since it will be called only * in case of singlestepping, if copy_from_user failed. */ - n = access_process_vm(current, addr, &instr, sizeof(instr), 0); + n = access_process_vm(current, addr, &instr, sizeof(instr), + FOLL_FORCE); if (n != sizeof(instr)) { printk(KERN_ERR "is_syscall : failed to read " "instruction from 0x%lx\n", addr); diff --git a/arch/x86/um/ptrace_64.c b/arch/x86/um/ptrace_64.c index 0b5c184..e30202b 100644 --- a/arch/x86/um/ptrace_64.c +++ b/arch/x86/um/ptrace_64.c @@ -212,7 +212,8 @@ int is_syscall(unsigned long addr) * slow, but that doesn't matter, since it will be called only * in case of singlestepping, if copy_from_user failed. */ - n = access_process_vm(current, addr, &instr, sizeof(instr), 0); + n = access_process_vm(current, addr, &instr, sizeof(instr), + FOLL_FORCE); if (n != sizeof(instr)) { printk("is_syscall : failed to read instruction from " "0x%lx\n", addr); diff --git a/include/linux/mm.h b/include/linux/mm.h index 3e5234e..7beda79 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1266,7 +1266,8 @@ static inline int fixup_user_fault(struct task_struct *tsk, } #endif
-extern int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write); +extern int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, + unsigned int gup_flags); extern int access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf, int len, unsigned int gup_flags);
diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 2a99027..e6474f7 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -537,7 +537,7 @@ int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst int this_len, retval;
this_len = (len > sizeof(buf)) ? sizeof(buf) : len; - retval = access_process_vm(tsk, src, buf, this_len, 0); + retval = access_process_vm(tsk, src, buf, this_len, FOLL_FORCE); if (!retval) { if (copied) break; @@ -564,7 +564,8 @@ int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long ds this_len = (len > sizeof(buf)) ? sizeof(buf) : len; if (copy_from_user(buf, src, this_len)) return -EFAULT; - retval = access_process_vm(tsk, dst, buf, this_len, 1); + retval = access_process_vm(tsk, dst, buf, this_len, + FOLL_FORCE | FOLL_WRITE); if (!retval) { if (copied) break; @@ -1127,7 +1128,7 @@ int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr, unsigned long tmp; int copied;
- copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0); + copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), FOLL_FORCE); if (copied != sizeof(tmp)) return -EIO; return put_user(tmp, (unsigned long __user *)data); @@ -1138,7 +1139,8 @@ int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr, { int copied;
- copied = access_process_vm(tsk, addr, &data, sizeof(data), 1); + copied = access_process_vm(tsk, addr, &data, sizeof(data), + FOLL_FORCE | FOLL_WRITE); return (copied == sizeof(data)) ? 0 : -EIO; }
@@ -1155,7 +1157,8 @@ int compat_ptrace_request(struct task_struct *child, compat_long_t request, switch (request) { case PTRACE_PEEKTEXT: case PTRACE_PEEKDATA: - ret = access_process_vm(child, addr, &word, sizeof(word), 0); + ret = access_process_vm(child, addr, &word, sizeof(word), + FOLL_FORCE); if (ret != sizeof(word)) ret = -EIO; else @@ -1164,7 +1167,8 @@ int compat_ptrace_request(struct task_struct *child, compat_long_t request,
case PTRACE_POKETEXT: case PTRACE_POKEDATA: - ret = access_process_vm(child, addr, &data, sizeof(data), 1); + ret = access_process_vm(child, addr, &data, sizeof(data), + FOLL_FORCE | FOLL_WRITE); ret = (ret != sizeof(data) ? -EIO : 0); break;
diff --git a/mm/memory.c b/mm/memory.c index bac2d99..e18c57b 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3951,20 +3951,16 @@ int access_remote_vm(struct mm_struct *mm, unsigned long addr, * Do not walk the page table directly, use get_user_pages */ int access_process_vm(struct task_struct *tsk, unsigned long addr, - void *buf, int len, int write) + void *buf, int len, unsigned int gup_flags) { struct mm_struct *mm; int ret; - unsigned int flags = FOLL_FORCE;
mm = get_task_mm(tsk); if (!mm) return 0;
- if (write) - flags |= FOLL_WRITE; - - ret = __access_remote_vm(tsk, mm, addr, buf, len, flags); + ret = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags);
mmput(mm);
diff --git a/mm/nommu.c b/mm/nommu.c index 93d5bb5..db5fd17 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -1861,7 +1861,8 @@ int access_remote_vm(struct mm_struct *mm, unsigned long addr, * Access another process' address space. * - source/target buffer must be kernel space */ -int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write) +int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, + unsigned int gup_flags) { struct mm_struct *mm;
@@ -1872,8 +1873,7 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, in if (!mm) return 0;
- len = __access_remote_vm(tsk, mm, addr, buf, len, - write ? FOLL_WRITE : 0); + len = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags);
mmput(mm); return len; diff --git a/mm/util.c b/mm/util.c index 4c685bd..952cbe7 100644 --- a/mm/util.c +++ b/mm/util.c @@ -624,7 +624,7 @@ int get_cmdline(struct task_struct *task, char *buffer, int buflen) if (len > buflen) len = buflen;
- res = access_process_vm(task, arg_start, buffer, len, 0); + res = access_process_vm(task, arg_start, buffer, len, FOLL_FORCE);
/* * If the nul at the end of args has been overwritten, then @@ -639,7 +639,8 @@ int get_cmdline(struct task_struct *task, char *buffer, int buflen) if (len > buflen - res) len = buflen - res; res += access_process_vm(task, env_start, - buffer+res, len, 0); + buffer+res, len, + FOLL_FORCE); res = strnlen(buffer, res); } }
On Thu, Oct 13, 2016 at 01:20:20AM +0100, Lorenzo Stoakes wrote:
This patch removes the write parameter from access_process_vm() and replaces it with a gup_flags parameter as use of this function previously _implied_ FOLL_FORCE, whereas after this patch callers explicitly pass this flag.
We make this explicit as use of FOLL_FORCE can result in surprising behaviour (and hence bugs) within the mm subsystem.
Signed-off-by: Lorenzo Stoakes lstoakes@gmail.com
arch/cris/arch-v32/kernel/ptrace.c | 4 ++--
For the CRIS part:
Acked-by: Jesper Nilsson jesper.nilsson@axis.com
/^JN - Jesper Nilsson
Lorenzo Stoakes lstoakes@gmail.com writes:
diff --git a/arch/powerpc/kernel/ptrace32.c b/arch/powerpc/kernel/ptrace32.c index f52b7db3..010b7b3 100644 --- a/arch/powerpc/kernel/ptrace32.c +++ b/arch/powerpc/kernel/ptrace32.c @@ -74,7 +74,7 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request, break;
copied = access_process_vm(child, (u64)addrOthers, &tmp,
sizeof(tmp), 0);
sizeof(tmp), FOLL_FORCE);
LGTM.
@@ -179,7 +179,8 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request, break; ret = 0; if (access_process_vm(child, (u64)addrOthers, &tmp,
sizeof(tmp), 1) == sizeof(tmp))
sizeof(tmp),FOLL_FORCE | FOLL_WRITE) == sizeof(tmp)) break;
If you're respinning this anyway, can you format that as:
if (access_process_vm(child, (u64)addrOthers, &tmp, sizeof(tmp), FOLL_FORCE | FOLL_WRITE) == sizeof(tmp)) break;
I realise you probably deliberately didn't do that to make the diff clearer.
Either way:
Acked-by: Michael Ellerman mpe@ellerman.id.au (powerpc)
cheers
Am 13.10.2016 um 02:20 schrieb Lorenzo Stoakes:
This patch series adjusts functions in the get_user_pages* family such that desired FOLL_* flags are passed as an argument rather than implied by flags.
The purpose of this change is to make the use of FOLL_FORCE explicit so it is easier to grep for and clearer to callers that this flag is being used. The use of FOLL_FORCE is an issue as it overrides missing VM_READ/VM_WRITE flags for the VMA whose pages we are reading from/writing to, which can result in surprising behaviour.
The patch series came out of the discussion around commit 38e0885, which addressed a BUG_ON() being triggered when a page was faulted in with PROT_NONE set but having been overridden by FOLL_FORCE. do_numa_page() was run on the assumption the page _must_ be one marked for NUMA node migration as an actual PROT_NONE page would have been dealt with prior to this code path, however FOLL_FORCE introduced a situation where this assumption did not hold.
See https://marc.info/?l=linux-mm&m=147585445805166 for the patch proposal.
Lorenzo Stoakes (10): mm: remove write/force parameters from __get_user_pages_locked() mm: remove write/force parameters from __get_user_pages_unlocked() mm: replace get_user_pages_unlocked() write/force parameters with gup_flags mm: replace get_user_pages_locked() write/force parameters with gup_flags mm: replace get_vaddr_frames() write/force parameters with gup_flags mm: replace get_user_pages() write/force parameters with gup_flags mm: replace get_user_pages_remote() write/force parameters with gup_flags mm: replace __access_remote_vm() write parameter with gup_flags mm: replace access_remote_vm() write parameter with gup_flags mm: replace access_process_vm() write parameter with gup_flags
Patch number 6 in this series (which touches drivers I co-maintain) is Acked-by: Christian König christian.koenig@amd.com.
In general looks like a very nice cleanup to me, but I'm not enlightened enough to full judge.
Regards, Christian.
arch/alpha/kernel/ptrace.c | 9 ++-- arch/blackfin/kernel/ptrace.c | 5 ++- arch/cris/arch-v32/drivers/cryptocop.c | 4 +- arch/cris/arch-v32/kernel/ptrace.c | 4 +- arch/ia64/kernel/err_inject.c | 2 +- arch/ia64/kernel/ptrace.c | 14 +++--- arch/m32r/kernel/ptrace.c | 15 ++++--- arch/mips/kernel/ptrace32.c | 5 ++- arch/mips/mm/gup.c | 2 +- arch/powerpc/kernel/ptrace32.c | 5 ++- arch/s390/mm/gup.c | 3 +- arch/score/kernel/ptrace.c | 10 +++-- arch/sh/mm/gup.c | 3 +- arch/sparc/kernel/ptrace_64.c | 24 +++++++---- arch/sparc/mm/gup.c | 3 +- arch/x86/kernel/step.c | 3 +- arch/x86/mm/gup.c | 2 +- arch/x86/mm/mpx.c | 5 +-- arch/x86/um/ptrace_32.c | 3 +- arch/x86/um/ptrace_64.c | 3 +- drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 7 ++- drivers/gpu/drm/etnaviv/etnaviv_gem.c | 7 ++- drivers/gpu/drm/exynos/exynos_drm_g2d.c | 3 +- drivers/gpu/drm/i915/i915_gem_userptr.c | 6 ++- drivers/gpu/drm/radeon/radeon_ttm.c | 3 +- drivers/gpu/drm/via/via_dmablit.c | 4 +- drivers/infiniband/core/umem.c | 6 ++- drivers/infiniband/core/umem_odp.c | 7 ++- drivers/infiniband/hw/mthca/mthca_memfree.c | 2 +- drivers/infiniband/hw/qib/qib_user_pages.c | 3 +- drivers/infiniband/hw/usnic/usnic_uiom.c | 5 ++- drivers/media/pci/ivtv/ivtv-udma.c | 4 +- drivers/media/pci/ivtv/ivtv-yuv.c | 5 ++- drivers/media/platform/omap/omap_vout.c | 2 +- drivers/media/v4l2-core/videobuf-dma-sg.c | 7 ++- drivers/media/v4l2-core/videobuf2-memops.c | 6 ++- drivers/misc/mic/scif/scif_rma.c | 3 +- drivers/misc/sgi-gru/grufault.c | 2 +- drivers/platform/goldfish/goldfish_pipe.c | 3 +- drivers/rapidio/devices/rio_mport_cdev.c | 3 +- drivers/scsi/st.c | 5 +-- .../interface/vchiq_arm/vchiq_2835_arm.c | 3 +- .../vc04_services/interface/vchiq_arm/vchiq_arm.c | 3 +- drivers/video/fbdev/pvr2fb.c | 4 +- drivers/virt/fsl_hypervisor.c | 4 +- fs/exec.c | 9 +++- fs/proc/base.c | 19 +++++--- include/linux/mm.h | 18 ++++---- kernel/events/uprobes.c | 6 ++- kernel/ptrace.c | 16 ++++--- mm/frame_vector.c | 9 ++-- mm/gup.c | 50 ++++++++++------------ mm/memory.c | 16 ++++--- mm/mempolicy.c | 2 +- mm/nommu.c | 38 +++++++--------- mm/process_vm_access.c | 7 ++- mm/util.c | 8 ++-- net/ceph/pagevec.c | 2 +- security/tomoyo/domain.c | 2 +- virt/kvm/async_pf.c | 3 +- virt/kvm/kvm_main.c | 11 +++-- 61 files changed, 260 insertions(+), 187 deletions(-) _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
On Thu 13-10-16 01:20:10, Lorenzo Stoakes wrote:
This patch series adjusts functions in the get_user_pages* family such that desired FOLL_* flags are passed as an argument rather than implied by flags.
The purpose of this change is to make the use of FOLL_FORCE explicit so it is easier to grep for and clearer to callers that this flag is being used. The use of FOLL_FORCE is an issue as it overrides missing VM_READ/VM_WRITE flags for the VMA whose pages we are reading from/writing to, which can result in surprising behaviour.
The patch series came out of the discussion around commit 38e0885, which addressed a BUG_ON() being triggered when a page was faulted in with PROT_NONE set but having been overridden by FOLL_FORCE. do_numa_page() was run on the assumption the page _must_ be one marked for NUMA node migration as an actual PROT_NONE page would have been dealt with prior to this code path, however FOLL_FORCE introduced a situation where this assumption did not hold.
See https://marc.info/?l=linux-mm&m=147585445805166 for the patch proposal.
I like this cleanup. Tracking FOLL_FORCE users was always a nightmare and the flag behavior is really subtle so we should better be explicit about it. I haven't gone through each patch separately but rather applied the whole series and checked the resulting diff. This all seems OK to me and feel free to add Acked-by: Michal Hocko mhocko@suse.com
I am wondering whether we can go further. E.g. it is not really clear to me whether we need an explicit FOLL_REMOTE when we can in fact check mm != current->mm and imply that. Maybe there are some contexts which wouldn't work, I haven't checked.
Then I am also wondering about FOLL_TOUCH behavior. __get_user_pages_unlocked has only few callers which used to be get_user_pages_unlocked before 1e9877902dc7e ("mm/gup: Introduce get_user_pages_remote()"). To me a dropped FOLL_TOUCH seems unintentional. Now that get_user_pages_unlocked has gup_flags argument I guess we might want to get rid of the __g-u-p-u version altogether, no?
__get_user_pages is quite low level and imho shouldn't be exported. It's only user - kvm - should rather pull those two functions to gup instead and export them. There is nothing really KVM specific in them.
I also cannot say I would be entirely thrilled about get_user_pages_locked, we only have one user which can simply do lock g-u-p unlock AFAICS.
I guess there is more work in that area and I do not want to impose all that work on you, but I couldn't resist once I saw you playing in that area ;) Definitely a good start!
On Tue, Oct 18, 2016 at 05:30:50PM +0200, Michal Hocko wrote:
I am wondering whether we can go further. E.g. it is not really clear to me whether we need an explicit FOLL_REMOTE when we can in fact check mm != current->mm and imply that. Maybe there are some contexts which wouldn't work, I haven't checked.
This flag is set even when /proc/self/mem is used. I've not looked deeply into this flag but perhaps accessing your own memory this way can be considered 'remote' since you're not accessing it directly. On the other hand, perhaps this is just mistaken in this case?
I guess there is more work in that area and I do not want to impose all that work on you, but I couldn't resist once I saw you playing in that area ;) Definitely a good start!
Thanks, I am more than happy to go as far down this rabbit hole as is helpful, no imposition at all :)
On Wed 19-10-16 09:58:15, Lorenzo Stoakes wrote:
On Tue, Oct 18, 2016 at 05:30:50PM +0200, Michal Hocko wrote:
I am wondering whether we can go further. E.g. it is not really clear to me whether we need an explicit FOLL_REMOTE when we can in fact check mm != current->mm and imply that. Maybe there are some contexts which wouldn't work, I haven't checked.
This flag is set even when /proc/self/mem is used. I've not looked deeply into this flag but perhaps accessing your own memory this way can be considered 'remote' since you're not accessing it directly. On the other hand, perhaps this is just mistaken in this case?
My understanding of the flag is quite limited as well. All I know it is related to protection keys and it is needed to bypass protection check. See arch_vma_access_permitted. See also 1b2ee1266ea6 ("mm/core: Do not enforce PKEY permissions on remote mm access").
On 10/19/2016 02:07 AM, Michal Hocko wrote:
On Wed 19-10-16 09:58:15, Lorenzo Stoakes wrote:
On Tue, Oct 18, 2016 at 05:30:50PM +0200, Michal Hocko wrote:
I am wondering whether we can go further. E.g. it is not really clear to me whether we need an explicit FOLL_REMOTE when we can in fact check mm != current->mm and imply that. Maybe there are some contexts which wouldn't work, I haven't checked.
This flag is set even when /proc/self/mem is used. I've not looked deeply into this flag but perhaps accessing your own memory this way can be considered 'remote' since you're not accessing it directly. On the other hand, perhaps this is just mistaken in this case?
My understanding of the flag is quite limited as well. All I know it is related to protection keys and it is needed to bypass protection check. See arch_vma_access_permitted. See also 1b2ee1266ea6 ("mm/core: Do not enforce PKEY permissions on remote mm access").
Yeah, we need the flag to tell us when PKEYs should be applied or not. The current task's PKRU (pkey rights register) should really only be used to impact access to the task's memory, but has no bearing on how a given task should access remote memory.
On Wed 19-10-16 09:49:43, Dave Hansen wrote:
On 10/19/2016 02:07 AM, Michal Hocko wrote:
On Wed 19-10-16 09:58:15, Lorenzo Stoakes wrote:
On Tue, Oct 18, 2016 at 05:30:50PM +0200, Michal Hocko wrote:
I am wondering whether we can go further. E.g. it is not really clear to me whether we need an explicit FOLL_REMOTE when we can in fact check mm != current->mm and imply that. Maybe there are some contexts which wouldn't work, I haven't checked.
This flag is set even when /proc/self/mem is used. I've not looked deeply into this flag but perhaps accessing your own memory this way can be considered 'remote' since you're not accessing it directly. On the other hand, perhaps this is just mistaken in this case?
My understanding of the flag is quite limited as well. All I know it is related to protection keys and it is needed to bypass protection check. See arch_vma_access_permitted. See also 1b2ee1266ea6 ("mm/core: Do not enforce PKEY permissions on remote mm access").
Yeah, we need the flag to tell us when PKEYs should be applied or not. The current task's PKRU (pkey rights register) should really only be used to impact access to the task's memory, but has no bearing on how a given task should access remote memory.
The question I had earlier was whether this has to be an explicit FOLL flag used by g-u-p users or we can just use it internally when mm != current->mm
On 10/19/2016 10:01 AM, Michal Hocko wrote:
The question I had earlier was whether this has to be an explicit FOLL flag used by g-u-p users or we can just use it internally when mm != current->mm
The reason I chose not to do that was that deferred work gets run under a basically random 'current'. If we just use 'mm != current->mm', then the deferred work will sometimes have pkeys enforced and sometimes not, basically randomly.
We want to be consistent with whether they are enforced or not, so we explicitly indicate that by calling the remote variant vs. plain.
dri-devel@lists.freedesktop.org
-
Christian König -
Dave Hansen -
Jan Kara -
Jesper Nilsson -
Lorenzo Stoakes -
Michael Ellerman -
Michal Hocko -
Paolo Bonzini