Commits
Michal Hocko committed d1b5c5671d0
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>