A "gfp_mask" is already passed to kasan_populate_vmalloc() as
an argument to respect GFPs from callers and KASAN uses it for
its internal allocations.

But apply_to_page_range() function ignores GFP flags due to a
hard-coded mask.

Wrap the call with memalloc_apply_gfp_scope()/memalloc_restore_scope()
so that non-blocking GFP flags(GFP_ATOMIC, GFP_NOWAIT) are respected.

Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
---
 mm/kasan/shadow.c | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c
index 11d472a5c4e8..c6643a72d9f6 100644
--- a/mm/kasan/shadow.c
+++ b/mm/kasan/shadow.c
@@ -377,18 +377,10 @@ static int __kasan_populate_vmalloc(unsigned long start, unsigned long end, gfp_
 		 * page tables allocations ignore external gfp mask, enforce it
 		 * by the scope API
 		 */
-		if ((gfp_mask & (__GFP_FS | __GFP_IO)) == __GFP_IO)
-			flags = memalloc_nofs_save();
-		else if ((gfp_mask & (__GFP_FS | __GFP_IO)) == 0)
-			flags = memalloc_noio_save();
-
+		flags = memalloc_apply_gfp_scope(gfp_mask);
 		ret = apply_to_page_range(&init_mm, start, nr_pages * PAGE_SIZE,
 					  kasan_populate_vmalloc_pte, &data);
-
-		if ((gfp_mask & (__GFP_FS | __GFP_IO)) == __GFP_IO)
-			memalloc_nofs_restore(flags);
-		else if ((gfp_mask & (__GFP_FS | __GFP_IO)) == 0)
-			memalloc_noio_restore(flags);
+		memalloc_restore_scope(flags);
 
 		___free_pages_bulk(data.pages, nr_pages);
 		if (ret)
-- 
2.47.3

On 9/15/25 3:40 PM, Uladzislau Rezki (Sony) wrote:
> A "gfp_mask" is already passed to kasan_populate_vmalloc() as
> an argument to respect GFPs from callers and KASAN uses it for
> its internal allocations.
> 
> But apply_to_page_range() function ignores GFP flags due to a
> hard-coded mask.
> 
> Wrap the call with memalloc_apply_gfp_scope()/memalloc_restore_scope()
> so that non-blocking GFP flags(GFP_ATOMIC, GFP_NOWAIT) are respected.
> 
> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
> Cc: Alexander Potapenko <glider@google.com>
> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
> ---

Reviewed-by: Andrey Ryabinin <ryabinin.a.a@gmail.com>

On 09/15/25 at 03:40pm, Uladzislau Rezki (Sony) wrote:
> A "gfp_mask" is already passed to kasan_populate_vmalloc() as
> an argument to respect GFPs from callers and KASAN uses it for
> its internal allocations.
> 
> But apply_to_page_range() function ignores GFP flags due to a
> hard-coded mask.
> 
> Wrap the call with memalloc_apply_gfp_scope()/memalloc_restore_scope()
> so that non-blocking GFP flags(GFP_ATOMIC, GFP_NOWAIT) are respected.
> 
> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
> Cc: Alexander Potapenko <glider@google.com>
> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
> ---
>  mm/kasan/shadow.c | 12 ++----------
>  1 file changed, 2 insertions(+), 10 deletions(-)

Reviewed-by: Baoquan He <bhe@redhat.com>

> 
> diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c
> index 11d472a5c4e8..c6643a72d9f6 100644
> --- a/mm/kasan/shadow.c
> +++ b/mm/kasan/shadow.c
> @@ -377,18 +377,10 @@ static int __kasan_populate_vmalloc(unsigned long start, unsigned long end, gfp_
>  		 * page tables allocations ignore external gfp mask, enforce it
>  		 * by the scope API
>  		 */
> -		if ((gfp_mask & (__GFP_FS | __GFP_IO)) == __GFP_IO)
> -			flags = memalloc_nofs_save();
> -		else if ((gfp_mask & (__GFP_FS | __GFP_IO)) == 0)
> -			flags = memalloc_noio_save();
> -
> +		flags = memalloc_apply_gfp_scope(gfp_mask);
>  		ret = apply_to_page_range(&init_mm, start, nr_pages * PAGE_SIZE,
>  					  kasan_populate_vmalloc_pte, &data);
> -
> -		if ((gfp_mask & (__GFP_FS | __GFP_IO)) == __GFP_IO)
> -			memalloc_nofs_restore(flags);
> -		else if ((gfp_mask & (__GFP_FS | __GFP_IO)) == 0)
> -			memalloc_noio_restore(flags);
> +		memalloc_restore_scope(flags);
>  
>  		___free_pages_bulk(data.pages, nr_pages);
>  		if (ret)
> -- 
> 2.47.3
>