linux-kernel - [PATCH v2 07/10] mm/kasan: Support non-blocking GFP in kasan_populate

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Message-ID: <20250915134041.151462-8-urezki@gmail.com>
Date: Mon, 15 Sep 2025 15:40:37 +0200
From: "Uladzislau Rezki (Sony)" <urezki@...il.com>
To: linux-mm@...ck.org,
	Andrew Morton <akpm@...ux-foundation.org>
Cc: Michal Hocko <mhocko@...nel.org>,
	Baoquan He <bhe@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Uladzislau Rezki <urezki@...il.com>,
	Andrey Ryabinin <ryabinin.a.a@...il.com>,
	Alexander Potapenko <glider@...gle.com>
Subject: [PATCH v2 07/10] 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.

Cc: Andrey Ryabinin <ryabinin.a.a@...il.com>
Cc: Alexander Potapenko <glider@...gle.com>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@...il.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