Re: [PATCH] mm/vmalloc, mm/kasan: respect gfp mask in kasan_populate_vmalloc()

[Andrey Ryabinin]

On 8/31/25 2:10 PM, Uladzislau Rezki (Sony) 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@xxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>
> Fixes: 451769ebb7e7 ("mm/vmalloc: alloc GFP_NO{FS,IO} for vmalloc")
> Signed-off-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx>
> ---

Reported-by: syzbot+3470c9ffee63e4abafeb@xxxxxxxxxxxxxxxxxxxxxxxxx
Reviewed-by: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>