From: Michal Hocko
Btrfs relies on GFP_NOFS allocation when commiting the transaction but
since "mm: page_alloc: do not lock up GFP_NOFS allocations upon OOM"
those allocations are allowed to fail which can lead to a pre-mature
transaction abort:
[ 55.328093] Call Trace:
[ 55.328890] [] dump_stack+0x4f/0x7b
[ 55.330518] [] ? console_unlock+0x334/0x363
[ 55.332738] [] __alloc_pages_nodemask+0x81d/0x8d4
[ 55.334910] [] pagecache_get_page+0x10e/0x20c
[ 55.336844] [] alloc_extent_buffer+0xd0/0x350 [btrfs]
[ 55.338973] [] btrfs_find_create_tree_block+0x15/0x17
[btrfs]
[ 55.341329] [] btrfs_alloc_tree_block+0x18c/0x405 [btrfs]
[ 55.343566] [] split_leaf+0x1e4/0x6a6 [btrfs]
[ 55.345577] [] btrfs_search_slot+0x671/0x831 [btrfs]
[ 55.347679] [] ? get_parent_ip+0xe/0x3e
[ 55.349434] [] btrfs_insert_empty_items+0x5d/0xa8 [btrfs]
[ 55.351681] [] __btrfs_run_delayed_refs+0x7a6/0xf35
[btrfs]
[ 55.353979] [] btrfs_run_delayed_refs+0x6e/0x226 [btrfs]
[ 55.356212] [] ? start_transaction+0x192/0x534 [btrfs]
[ 55.358378] [] ? start_transaction+0x192/0x534 [btrfs]
[ 55.360626] [] btrfs_commit_transaction+0x4c/0xaba [btrfs]
[ 55.362894] [] ? start_transaction+0x192/0x534 [btrfs]
[ 55.365221] [] btrfs_sync_file+0x29c/0x310 [btrfs]
[ 55.367273] [] vfs_fsync_range+0x8f/0x9e
[ 55.369047] [] vfs_fsync+0x1c/0x1e
[ 55.370654] [] do_fsync+0x34/0x4e
[ 55.372246] [] SyS_fsync+0x10/0x14
[ 55.373851] [] system_call_fastpath+0x12/0x6f
[ 55.381070] BTRFS: error (device hdb1) in btrfs_run_delayed_refs:2821:
errno=-12 Out of memory
[ 55.382431] BTRFS warning (device hdb1): Skipping commit of aborted
transaction.
[ 55.382433] BTRFS warning (device hdb1): cleanup_transaction:1692: Aborting
unused transaction(IO failure).
[ 55.384280] [ cut here ]
[ 55.384312] WARNING: CPU: 0 PID: 3010 at fs/btrfs/delayed-ref.c:438
btrfs_select_ref_head+0xd9/0xfe [btrfs]()
[...]
[ 55.384337] Call Trace:
[ 55.384353] [] dump_stack+0x4f/0x7b
[ 55.384357] [] ? down_trylock+0x2d/0x37
[ 55.384359] [] warn_slowpath_common+0xa1/0xbb
[ 55.384398] [] ? btrfs_select_ref_head+0xd9/0xfe [btrfs]
[ 55.384400] [] warn_slowpath_null+0x1a/0x1c
[ 55.384423] [] btrfs_select_ref_head+0xd9/0xfe [btrfs]
[ 55.384446] [] ? __btrfs_run_delayed_refs+0xa2/0xf35
[btrfs]
[ 55.384455] [] __btrfs_run_delayed_refs+0xab/0xf35 [btrfs]
[ 55.384476] [] btrfs_run_delayed_refs+0x6e/0x226 [btrfs]
[ 55.384499] [] ? start_transaction+0x192/0x534 [btrfs]
[ 55.384521] [] ? start_transaction+0x192/0x534 [btrfs]
[ 55.384543] [] btrfs_commit_transaction+0x4c/0xaba [btrfs]
[ 55.384565] [] ? start_transaction+0x192/0x534 [btrfs]
[ 55.384588] [] btrfs_sync_file+0x29c/0x310 [btrfs]
[ 55.384591] [] vfs_fsync_range+0x8f/0x9e
[ 55.384592] [] vfs_fsync+0x1c/0x1e
[ 55.384593] [] do_fsync+0x34/0x4e
[ 55.384594] [] SyS_fsync+0x10/0x14
[ 55.384595] [] system_call_fastpath+0x12/0x6f
[...]
[ 55.384608] ---[ end trace c29799da1d4dd621 ]---
[ 55.437323] BTRFS info (device hdb1): forced readonly
[ 55.438815] BTRFS info (device hdb1): delayed_refs has NO entry
Fix this by reintroducing the no-fail behavior of this allocation path
with the explicit __GFP_NOFAIL.
Signed-off-by: Michal Hocko
---
fs/btrfs/extent_io.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index c374e1e71e5f..88fad7051e38 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -4607,7 +4607,7 @@ __alloc_extent_buffer(struct btrfs_fs_info *fs_info, u64
start,
{
struct extent_buffer *eb = NULL;
- eb = kmem_cache_zalloc(extent_buffer_cache, GFP_NOFS);
+ eb = kmem_cache_zalloc(extent_buffer_cache, GFP_NOFS|__GFP_NOFAIL);
if (eb == NULL)
return NULL;
eb->start = start;
@@ -4867,7 +4867,7 @@ struct extent_buffer *alloc_extent_buffer(struct
btrfs_fs_info *fs_info,
return NULL;
for (i = 0; i < num_pages; i++, index++) {
- p = find_or_create_page(mapping, index, GFP_NOFS);
+ p = find_or_create_page(mapping, index, GFP_NOFS|__GFP_NOFAIL);
if (!p)
goto free_eb;
--
2.5.0
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
