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

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>