[PATCH RFC v4 12/42] kmsan: stackdepot: don't allocate KMSAN metadata for stackdepot

[glider@google.com]

We assume an uninitialized value couldn't come from stackdepot, so
we don't track stackdepot allocations with KMSAN.

Signed-off-by: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: linux-mm@kvack.org
---

v4:
 - set __GFP_NO_KMSAN_SHADOW explicitly for allocations

Change-Id: Ic3ec9b3dff3fff2732d874508a3582fb26ff0b1f
---
 lib/stackdepot.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/stackdepot.c b/lib/stackdepot.c
index ecd1a0dfb3fb..2e7d2232ed3c 100644
--- a/lib/stackdepot.c
+++ b/lib/stackdepot.c
@@ -295,7 +295,7 @@ depot_stack_handle_t stack_depot_save(unsigned long *entries,
 		 */
 		alloc_flags &= ~GFP_ZONEMASK;
 		alloc_flags &= (GFP_ATOMIC | GFP_KERNEL);
-		alloc_flags |= __GFP_NOWARN;
+		alloc_flags |= (__GFP_NOWARN | __GFP_NO_KMSAN_SHADOW);
 		page = alloc_pages(alloc_flags, STACK_ALLOC_ORDER);
 		if (page)
 			prealloc = page_address(page);
-- 
2.24.1.735.g03f4e72817-goog