linux-kernel - [PATCH] test_meminit: use GFP_ATOMIC in RCU critical section

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Message-Id: <20190725121703.210874-1-glider@google.com>
Date:   Thu, 25 Jul 2019 14:17:03 +0200
From:   Alexander Potapenko <glider@...gle.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     Alexander Potapenko <glider@...gle.com>,
        Kees Cook <keescook@...omium.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-security-module@...r.kernel.org
Subject: [PATCH] test_meminit: use GFP_ATOMIC in RCU critical section

kmalloc() shouldn't sleep while in RCU critical section, therefore
use GFP_ATOMIC instead of GFP_KERNEL.

The bug has been spotted by the 0day kernel testing robot.

Fixes: 7e659650cbda ("lib: introduce test_meminit module")
Signed-off-by: Alexander Potapenko <glider@...gle.com>
Cc: Kees Cook <keescook@...omium.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org
Cc: linux-mm@...ck.org
Cc: linux-security-module@...r.kernel.org
---
 lib/test_meminit.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/test_meminit.c b/lib/test_meminit.c
index 62d19f270cad..9729f271d150 100644
--- a/lib/test_meminit.c
+++ b/lib/test_meminit.c
@@ -222,7 +222,7 @@ static int __init do_kmem_cache_size(size_t size, bool want_ctor,
 		 * Copy the buffer to check that it's not wiped on
 		 * free().
 		 */
-		buf_copy = kmalloc(size, GFP_KERNEL);
+		buf_copy = kmalloc(size, GFP_ATOMIC);
 		if (buf_copy)
 			memcpy(buf_copy, buf, size);
 
-- 
2.22.0.657.g960e92d24f-goog