On 2/19/19 12:04 PM, jglisse@redhat.com wrote:
From: Jérôme Glisse jglisse@redhat.com
Helper to test if a range is updated to read only (it is still valid to read from the range). This is useful for device driver or anyone who wish to optimize out update when they know that they already have the range map read only.
Signed-off-by: Jérôme Glisse jglisse@redhat.com Cc: Christian König christian.koenig@amd.com Cc: Joonas Lahtinen joonas.lahtinen@linux.intel.com Cc: Jani Nikula jani.nikula@linux.intel.com Cc: Rodrigo Vivi rodrigo.vivi@intel.com Cc: Jan Kara jack@suse.cz Cc: Andrea Arcangeli aarcange@redhat.com Cc: Peter Xu peterx@redhat.com Cc: Felix Kuehling Felix.Kuehling@amd.com Cc: Jason Gunthorpe jgg@mellanox.com Cc: Ross Zwisler zwisler@kernel.org Cc: Dan Williams dan.j.williams@intel.com Cc: Paolo Bonzini pbonzini@redhat.com Cc: Radim Krčmář rkrcmar@redhat.com Cc: Michal Hocko mhocko@kernel.org Cc: Christian Koenig christian.koenig@amd.com Cc: Ralph Campbell rcampbell@nvidia.com Cc: John Hubbard jhubbard@nvidia.com Cc: kvm@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linux-rdma@vger.kernel.org Cc: Arnd Bergmann arnd@arndb.de
include/linux/mmu_notifier.h | 4 ++++ mm/mmu_notifier.c | 10 ++++++++++ 2 files changed, 14 insertions(+)
diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h index 0379956fff23..b6c004bd9f6a 100644 --- a/include/linux/mmu_notifier.h +++ b/include/linux/mmu_notifier.h @@ -259,6 +259,8 @@ extern void __mmu_notifier_invalidate_range_end(struct mmu_notifier_range *r, bool only_end); extern void __mmu_notifier_invalidate_range(struct mm_struct *mm, unsigned long start, unsigned long end); +extern bool +mmu_notifier_range_update_to_read_only(const struct mmu_notifier_range *range);
static inline bool mmu_notifier_range_blockable(const struct mmu_notifier_range *range) @@ -568,6 +570,8 @@ static inline void mmu_notifier_mm_destroy(struct mm_struct *mm) { }
+#define mmu_notifier_range_update_to_read_only(r) false
- #define ptep_clear_flush_young_notify ptep_clear_flush_young #define pmdp_clear_flush_young_notify pmdp_clear_flush_young #define ptep_clear_young_notify ptep_test_and_clear_young
diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c index abd88c466eb2..ee36068077b6 100644 --- a/mm/mmu_notifier.c +++ b/mm/mmu_notifier.c @@ -395,3 +395,13 @@ void mmu_notifier_unregister_no_release(struct mmu_notifier *mn, mmdrop(mm); } EXPORT_SYMBOL_GPL(mmu_notifier_unregister_no_release);
+bool +mmu_notifier_range_update_to_read_only(const struct mmu_notifier_range *range) +{
- if (!range->vma || range->event != MMU_NOTIFY_PROTECTION_VMA)
return false;- /* Return true if the vma still have the read flag set. */
- return range->vma->vm_flags & VM_READ;
+} +EXPORT_SYMBOL_GPL(mmu_notifier_range_update_to_read_only);
Don't you have to check for !WRITE & READ? mprotect() can change the permissions from R/O to RW and end up calling mmu_notifier_range_init() and mmu_notifier_invalidate_range_start()/end().
I'm not sure how useful this is since only applies to the MMU_NOTIFY_PROTECTION_VMA case. Anyway, you can add
Reviewed-by: Ralph Campbell rcampbell@nvidia.com