On Sun, Aug 31, 2025 at 12:24:10PM -0700, Andrew Morton wrote:
On Sun, 31 Aug 2025 14:10:58 +0200 "Uladzislau Rezki (Sony)" urezki@gmail.com wrote:
kasan_populate_vmalloc() and its helpers ignore the caller's gfp_mask and always allocate memory using the hardcoded GFP_KERNEL flag. This makes them inconsistent with vmalloc(), which was recently extended to support GFP_NOFS and GFP_NOIO allocations.
Page table allocations performed during shadow population also ignore the external gfp_mask. To preserve the intended semantics of GFP_NOFS and GFP_NOIO, wrap the apply_to_page_range() calls into the appropriate memalloc scope.
This patch:
- Extends kasan_populate_vmalloc() and helpers to take gfp_mask;
- Passes gfp_mask down to alloc_pages_bulk() and __get_free_page();
- Enforces GFP_NOFS/NOIO semantics with memalloc_*_save()/restore() around apply_to_page_range();
- Updates vmalloc.c and percpu allocator call sites accordingly.
To: Andrey Ryabinin ryabinin.a.a@gmail.com Cc: stable@vger.kernel.org Fixes: 451769ebb7e7 ("mm/vmalloc: alloc GFP_NO{FS,IO} for vmalloc") Signed-off-by: Uladzislau Rezki (Sony) urezki@gmail.com
Why cc:stable?
To justify this we'll need a description of the userspace visible effects of the bug please. We should always provide this information when fixing something. Or when adding something. Basically, all the time ;)
Yes, i am not aware about any report. I was thinking more about that "mm/vmalloc: alloc GFP_NO{FS,IO} for vmalloc" was incomplete and thus is a good candidate for stable.
We can drop it for the stable until there are some reports from people. If there are :)
Thanks!
-- Uladzislau Rezki