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btrfs: Prevent from early transaction abort 

Btrfs 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) so this is not a problem
currently but there is an attempt to move away from the default no-fail
behavior and allow these allocation to fail more eagerly. And this would
lead to a pre-mature transaction abort as follows:

[   55.328093] Call Trace:
[   55.328890]  [<ffffffff8154e6f0>] dump_stack+0x4f/0x7b
[   55.330518]  [<ffffffff8108fa28>] ? console_unlock+0x334/0x363
[   55.332738]  [<ffffffff8110873e>] __alloc_pages_nodemask+0x81d/0x8d4
[   55.334910]  [<ffffffff81100752>] pagecache_get_page+0x10e/0x20c
[   55.336844]  [<ffffffffa007d916>] alloc_extent_buffer+0xd0/0x350 [btrfs]
[   55.338973]  [<ffffffffa0059d8c>] btrfs_find_create_tree_block+0x15/0x17 [btrfs]
[   55.341329]  [<ffffffffa004f728>] btrfs_alloc_tree_block+0x18c/0x405 [btrfs]
[   55.343566]  [<ffffffffa003fa34>] split_leaf+0x1e4/0x6a6 [btrfs]
[   55.345577]  [<ffffffffa0040567>] btrfs_search_slot+0x671/0x831 [btrfs]
[   55.347679]  [<ffffffff810682d7>] ? get_parent_ip+0xe/0x3e
[   55.349434]  [<ffffffffa0041cb2>] btrfs_insert_empty_items+0x5d/0xa8 [btrfs]
[   55.351681]  [<ffffffffa004ecfb>] __btrfs_run_delayed_refs+0x7a6/0xf35 [btrfs]
[   55.353979]  [<ffffffffa00512ea>] btrfs_run_delayed_refs+0x6e/0x226 [btrfs]
[   55.356212]  [<ffffffffa0060e21>] ? start_transaction+0x192/0x534 [btrfs]
[   55.358378]  [<ffffffffa0060e21>] ? start_transaction+0x192/0x534 [btrfs]
[   55.360626]  [<ffffffffa0060221>] btrfs_commit_transaction+0x4c/0xaba [btrfs]
[   55.362894]  [<ffffffffa0060e21>] ? start_transaction+0x192/0x534 [btrfs]
[   55.365221]  [<ffffffffa0073428>] btrfs_sync_file+0x29c/0x310 [btrfs]
[   55.367273]  [<ffffffff81186808>] vfs_fsync_range+0x8f/0x9e
[   55.369047]  [<ffffffff81186833>] vfs_fsync+0x1c/0x1e
[   55.370654]  [<ffffffff81186869>] do_fsync+0x34/0x4e
[   55.372246]  [<ffffffff81186ab3>] SyS_fsync+0x10/0x14
[   55.373851]  [<ffffffff81554f97>] 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]  [<ffffffff8154e6f0>] dump_stack+0x4f/0x7b
[   55.384357]  [<ffffffff8107f717>] ? down_trylock+0x2d/0x37
[   55.384359]  [<ffffffff81046977>] warn_slowpath_common+0xa1/0xbb
[   55.384398]  [<ffffffffa00a1d6b>] ? btrfs_select_ref_head+0xd9/0xfe [btrfs]
[   55.384400]  [<ffffffff81046a34>] warn_slowpath_null+0x1a/0x1c
[   55.384423]  [<ffffffffa00a1d6b>] btrfs_select_ref_head+0xd9/0xfe [btrfs]
[   55.384446]  [<ffffffffa004e5f7>] ? __btrfs_run_delayed_refs+0xa2/0xf35 [btrfs]
[   55.384455]  [<ffffffffa004e600>] __btrfs_run_delayed_refs+0xab/0xf35 [btrfs]
[   55.384476]  [<ffffffffa00512ea>] btrfs_run_delayed_refs+0x6e/0x226 [btrfs]
[   55.384499]  [<ffffffffa0060e21>] ? start_transaction+0x192/0x534 [btrfs]
[   55.384521]  [<ffffffffa0060e21>] ? start_transaction+0x192/0x534 [btrfs]
[   55.384543]  [<ffffffffa0060221>] btrfs_commit_transaction+0x4c/0xaba [btrfs]
[   55.384565]  [<ffffffffa0060e21>] ? start_transaction+0x192/0x534 [btrfs]
[   55.384588]  [<ffffffffa0073428>] btrfs_sync_file+0x29c/0x310 [btrfs]
[   55.384591]  [<ffffffff81186808>] vfs_fsync_range+0x8f/0x9e
[   55.384592]  [<ffffffff81186833>] vfs_fsync+0x1c/0x1e
[   55.384593]  [<ffffffff81186869>] do_fsync+0x34/0x4e
[   55.384594]  [<ffffffff81186ab3>] SyS_fsync+0x10/0x14
[   55.384595]  [<ffffffff81554f97>] 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 being explicit about the no-fail behavior of this allocation
path and use __GFP_NOFAIL.

Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
This commit is contained in:
Michal Hocko 2015-08-19 14:17:40 +02:00 committed by Chris Mason
parent 60d53eb310
commit d1b5c5671d
1 changed files with 2 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
fs/btrfs/extent_io.c
View File

@ -4624,9 +4624,7 @@ __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);
if (eb == NULL)
return NULL;
eb = kmem_cache_zalloc(extent_buffer_cache, GFP_NOFS|__GFP_NOFAIL);
eb->start = start;
eb->len = len;
eb->fs_info = fs_info;
@ -4884,7 +4882,7 @@ 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;