linux-kernel - [PATCH 2/2] btrfs: use __GFP_NOFAIL in alloc_btrfs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1439986661-15896-3-git-send-email-mhocko@kernel.org>
Date:	Wed, 19 Aug 2015 14:17:41 +0200
From:	mhocko@...nel.org
To:	linux-btrfs@...r.kernel.org
Cc:	Chris Mason <clm@...com>, Josef Bacik <jbacik@...com>,
	David Sterba <dsterba@...e.cz>, linux-kernel@...r.kernel.org,
	Michal Hocko <mhocko@...e.com>
Subject: [PATCH 2/2] btrfs: use __GFP_NOFAIL in alloc_btrfs_bio

From: Michal Hocko <mhocko@...e.com>

alloc_btrfs_bio relies on GFP_NOFS allocation when committing the
transaction but this allocation context is rather weak wrt. reclaim
capabilities. The page allocator currently tries hard to not fail these
allocations if they are small (<=PAGE_ALLOC_COSTLY_ORDER) but it can
still fail if the _current_ process is the OOM killer victim. Moreover
there is an attempt to move away from the default no-fail behavior and
allow these allocation to fail more eagerly. This would lead to:

[   37.928625] kernel BUG at fs/btrfs/extent_io.c:4045

which is clearly undesirable and the nofail behavior should be explicit
if the allocation failure cannot be tolerated.

Signed-off-by: Michal Hocko <mhocko@...e.com>
---
 fs/btrfs/volumes.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 53af23f2c087..42b9949dd71d 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -4914,9 +4914,7 @@ static struct btrfs_bio *alloc_btrfs_bio(int total_stripes, int real_stripes)
 		 * and the stripes
 		 */
 		sizeof(u64) * (total_stripes),
-		GFP_NOFS);
-	if (!bbio)
-		return NULL;
+		GFP_NOFS|__GFP_NOFAIL);

 	atomic_set(&bbio->error, 0);
 	atomic_set(&bbio->refs, 1);
-- 
2.5.0

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/