Commit ad435e79 authored Oct 07, 2025 by Uladzislau Rezki (Sony) Committed by Andrew Morton Nov 16, 2025

mm/kasan: support non-blocking GFP in kasan_populate_vmalloc()

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.

Link: https://lkml.kernel.org/r/20251007122035.56347-7-urezki@gmail.com


Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

parent 8da89ba1

mm/kasan/shadow.c

+2 −10

Original line number	Diff line number	Diff line
		@@ -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)