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[RFC 8/8] btrfs: use __GFP_NOFAIL in alloc_btrfs_bio

Started bymhocko@kernel.org
First post2015-08-05 12:00 +0200
Last post2015-08-18 12:50 +0200
Articles 3 — 3 participants

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  [RFC 8/8] btrfs: use __GFP_NOFAIL in alloc_btrfs_bio mhocko@kernel.org - 2015-08-05 12:00 +0200
    Re: [RFC 8/8] btrfs: use __GFP_NOFAIL in alloc_btrfs_bio David Sterba <dsterba@suse.com> - 2015-08-05 18:40 +0200
    [RFC -v2 8/8] btrfs: use __GFP_NOFAIL in alloc_btrfs_bio Michal Hocko <mhocko@kernel.org> - 2015-08-18 12:50 +0200

#1200608 — [RFC 8/8] btrfs: use __GFP_NOFAIL in alloc_btrfs_bio

Frommhocko@kernel.org
Date2015-08-05 12:00 +0200
Subject[RFC 8/8] btrfs: use __GFP_NOFAIL in alloc_btrfs_bio
Message-ID<pU3En-66q-31@gated-at.bofh.it>
From: Michal Hocko <mhocko@suse.com>

alloc_btrfs_bio is relying on GFP_NOFS to allocate a bio but since "mm:
page_alloc: do not lock up GFP_NOFS allocations upon OOM" this is
allowed to fail which can lead to
[   37.928625] kernel BUG at fs/btrfs/extent_io.c:4045

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

Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 fs/btrfs/volumes.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 53af23f2c087..57a99d19533d 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -4914,7 +4914,7 @@ static struct btrfs_bio *alloc_btrfs_bio(int total_stripes, int real_stripes)
 		 * and the stripes
 		 */
 		sizeof(u64) * (total_stripes),
-		GFP_NOFS);
+		GFP_NOFS|__GFP_NOFAIL);
 	if (!bbio)
 		return NULL;
 
-- 
2.5.0

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#1200972

FromDavid Sterba <dsterba@suse.com>
Date2015-08-05 18:40 +0200
Message-ID<pU9Ts-6QK-9@gated-at.bofh.it>
In reply to#1200608
On Wed, Aug 05, 2015 at 11:51:24AM +0200, mhocko@kernel.org wrote:
> From: Michal Hocko <mhocko@suse.com>
> 
> alloc_btrfs_bio is relying on GFP_NOFS to allocate a bio but since "mm:
> page_alloc: do not lock up GFP_NOFS allocations upon OOM" this is
> allowed to fail which can lead to
> [   37.928625] kernel BUG at fs/btrfs/extent_io.c:4045
> 
> This is clearly undesirable and the nofail behavior should be explicit
> if the allocation failure cannot be tolerated.
> 
> Signed-off-by: Michal Hocko <mhocko@suse.com>

Reviewed-by: David Sterba <dsterba@suse.com>
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#1209177 — [RFC -v2 8/8] btrfs: use __GFP_NOFAIL in alloc_btrfs_bio

FromMichal Hocko <mhocko@kernel.org>
Date2015-08-18 12:50 +0200
Subject[RFC -v2 8/8] btrfs: use __GFP_NOFAIL in alloc_btrfs_bio
Message-ID<pYMCR-3Kd-7@gated-at.bofh.it>
In reply to#1200608
From: Michal Hocko <mhocko@suse.com>

alloc_btrfs_bio is relying on GFP_NOFS to allocate a bio but since "mm:
page_alloc: do not lock up GFP_NOFS allocations upon OOM" this is
allowed to fail which can lead to
[   37.928625] kernel BUG at fs/btrfs/extent_io.c:4045

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

Signed-off-by: Michal Hocko <mhocko@suse.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

-- 
Michal Hocko
SUSE Labs
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