On Wed, Apr 08, 2020 at 01:59:08PM +0200, Christoph Hellwig wrote:
This allows to unexport map_vm_area and unmap_kernel_range, which are rather deep internal and should not be available to modules.
Even though I don't know how many usecase we have using zsmalloc as module(I heard only once by dumb reason), it could affect existing users. Thus, please include concrete explanation in the patch to justify when the complain occurs.
Signed-off-by: Christoph Hellwig hch@lst.de
mm/Kconfig | 2 +- mm/vmalloc.c | 2 -- 2 files changed, 1 insertion(+), 3 deletions(-)
diff --git a/mm/Kconfig b/mm/Kconfig index 36949a9425b8..614cc786b519 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -702,7 +702,7 @@ config ZSMALLOC
config ZSMALLOC_PGTABLE_MAPPING bool "Use page table mapping to access object in zsmalloc"
- depends on ZSMALLOC
- depends on ZSMALLOC=y help By default, zsmalloc uses a copy-based object mapping method to access allocations that span two pages. However, if a particular
diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 3375f9508ef6..9183fc0d365a 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -2046,7 +2046,6 @@ void unmap_kernel_range(unsigned long addr, unsigned long size) vunmap_page_range(addr, end); flush_tlb_kernel_range(addr, end); } -EXPORT_SYMBOL_GPL(unmap_kernel_range);
int map_vm_area(struct vm_struct *area, pgprot_t prot, struct page **pages) { @@ -2058,7 +2057,6 @@ int map_vm_area(struct vm_struct *area, pgprot_t prot, struct page **pages)
return err > 0 ? 0 : err; } -EXPORT_SYMBOL_GPL(map_vm_area);
static inline void setup_vmalloc_vm_locked(struct vm_struct *vm, struct vmap_area *va, unsigned long flags, const void *caller) -- 2.25.1
On Thu, Apr 09, 2020 at 09:08:26AM -0700, Minchan Kim wrote:
On Wed, Apr 08, 2020 at 01:59:08PM +0200, Christoph Hellwig wrote:
This allows to unexport map_vm_area and unmap_kernel_range, which are rather deep internal and should not be available to modules.
Even though I don't know how many usecase we have using zsmalloc as module(I heard only once by dumb reason), it could affect existing users. Thus, please include concrete explanation in the patch to justify when the complain occurs.
The justification is 'we can unexport functions that have no sane reason of being exported in the first place'.
The Changelog pretty much says that.
On Thu, Apr 09, 2020 at 06:50:30PM +0200, Peter Zijlstra wrote:
On Thu, Apr 09, 2020 at 09:08:26AM -0700, Minchan Kim wrote:
On Wed, Apr 08, 2020 at 01:59:08PM +0200, Christoph Hellwig wrote:
This allows to unexport map_vm_area and unmap_kernel_range, which are rather deep internal and should not be available to modules.
Even though I don't know how many usecase we have using zsmalloc as module(I heard only once by dumb reason), it could affect existing users. Thus, please include concrete explanation in the patch to justify when the complain occurs.
The justification is 'we can unexport functions that have no sane reason of being exported in the first place'.
The Changelog pretty much says that.
Okay, I hope there is no affected user since this patch. If there are someone, they need to provide sane reason why they want to have zsmalloc as module.
Acked-by: Minchan Kim minchan@kernel.org
On (20/04/09 10:08), Minchan Kim wrote:
Even though I don't know how many usecase we have using zsmalloc as module(I heard only once by dumb reason), it could affect existing users. Thus, please include concrete explanation in the patch to justify when the complain occurs.
The justification is 'we can unexport functions that have no sane reason of being exported in the first place'.
The Changelog pretty much says that.
Okay, I hope there is no affected user since this patch. If there are someone, they need to provide sane reason why they want to have zsmalloc as module.
I'm one of those who use zsmalloc as a module - mainly because I use zram as a compressing general purpose block device, not as a swap device. I create zram0, mkfs, mount, checkout and compile code, once done - umount, rmmod. This reduces the number of writes to SSD. Some people use tmpfs, but zram device(-s) can be much larger in size. That's a niche use case and I'm not against the patch.
-ss
Hi Sergey,
On Fri, Apr 10, 2020 at 11:38:45AM +0900, Sergey Senozhatsky wrote:
On (20/04/09 10:08), Minchan Kim wrote:
Even though I don't know how many usecase we have using zsmalloc as module(I heard only once by dumb reason), it could affect existing users. Thus, please include concrete explanation in the patch to justify when the complain occurs.
The justification is 'we can unexport functions that have no sane reason of being exported in the first place'.
The Changelog pretty much says that.
Okay, I hope there is no affected user since this patch. If there are someone, they need to provide sane reason why they want to have zsmalloc as module.
I'm one of those who use zsmalloc as a module - mainly because I use zram as a compressing general purpose block device, not as a swap device. I create zram0, mkfs, mount, checkout and compile code, once done - umount, rmmod. This reduces the number of writes to SSD. Some people use tmpfs, but zram device(-s) can be much larger in size. That's a niche use case and I'm not against the patch.
It doesn't mean we couldn't use zsmalloc as module any longer. It means we couldn't use zsmalloc as module with pgtable mapping whcih was little bit faster on microbenchmark in some architecutre(However, I usually temped to remove it since it had several problems). However, we could still use zsmalloc as module as copy way instead of pgtable mapping. Thus, if someone really want to rollback the feature, they should provide reasonable reason why it doesn't work for them. "A little fast" wouldn't be enough to exports deep internal to the module.
Thanks.
dri-devel@lists.freedesktop.org
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Minchan Kim -
Peter Zijlstra -
Sergey Senozhatsky