Ядро устало ждать, пока btrfs отвиснет.

[ 1199.002162] INFO: task mount:943 blocked for more than 120 seconds.
[ 1199.003554]       Not tainted 3.19.2-1-ARCH #1
[ 1199.005111] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 1199.006746] mount           D ffff88020362f7f8     0   943    457 0x00000000
[ 1199.006756]  ffff88020362f7f8 ffff88007fe0c590 0000000000013f00 ffff88020362ffd8
[ 1199.006763]  0000000000013f00 ffff8802152409f0 ffff88007fe0c590 ffff88017a3b2000
[ 1199.006768]  0000000000000001 ffff88020362f758 ffffffffa0941c91 ffff88017a3b2000
[ 1199.006775] Call Trace:
[ 1199.006811]  [<ffffffffa0941c91>] ? set_extent_buffer_dirty+0x71/0xc0 [btrfs]
[ 1199.006833]  [<ffffffffa0917796>] ? btrfs_buffer_uptodate+0x56/0x80 [btrfs]
[ 1199.006843]  [<ffffffff8155e999>] schedule+0x29/0x70
[ 1199.006865]  [<ffffffffa0959745>] btrfs_tree_lock+0x65/0x200 [btrfs]
[ 1199.006877]  [<ffffffff810b4380>] ? wait_woken+0x90/0x90
[ 1199.006891]  [<ffffffffa08f7cd9>] btrfs_search_slot+0x799/0xaa0 [btrfs]
[ 1199.006897]  [<ffffffff810b43c0>] ? autoremove_wake_function+0x40/0x40
[ 1199.006911]  [<ffffffffa08f99f5>] btrfs_insert_empty_items+0x75/0xd0 [btrfs]
[ 1199.006932]  [<ffffffffa0959a37>] btrfs_insert_orphan_item+0x67/0xa0 [btrfs]
[ 1199.006950]  [<ffffffffa095c12e>] insert_orphan_item+0x5e/0x90 [btrfs]
[ 1199.006967]  [<ffffffffa095e531>] replay_one_buffer+0x361/0x380 [btrfs]
[ 1199.006992]  [<ffffffffa0941244>] ? alloc_extent_buffer+0x34/0x370 [btrfs]
[ 1199.007010]  [<ffffffffa095a8f3>] walk_down_log_tree+0x1d3/0x410 [btrfs]
[ 1199.007026]  [<ffffffffa095abfb>] walk_log_tree+0xcb/0x1d0 [btrfs]
[ 1199.007046]  [<ffffffffa09627f7>] btrfs_recover_log_trees+0x1e7/0x490 [btrfs]
[ 1199.007063]  [<ffffffffa095e1d0>] ? replay_one_dir_item+0xf0/0xf0 [btrfs]
[ 1199.007084]  [<ffffffffa091ab3e>] open_ctree+0x17ae/0x2030 [btrfs]
[ 1199.007100]  [<ffffffffa08ef633>] btrfs_mount+0x843/0x920 [btrfs]
[ 1199.007108]  [<ffffffff8117b7aa>] ? pcpu_alloc+0x35a/0x680
[ 1199.007117]  [<ffffffff811d5d68>] mount_fs+0x38/0x1c0
[ 1199.007124]  [<ffffffff8117bb05>] ? __alloc_percpu+0x15/0x20
[ 1199.007130]  [<ffffffff811f116b>] vfs_kern_mount+0x6b/0x120
[ 1199.007136]  [<ffffffff811f4184>] do_mount+0x224/0xb40
[ 1199.007142]  [<ffffffff811f4dae>] SyS_mount+0x7e/0xe0
[ 1199.007150]  [<ffffffff81562809>] system_call_fastpath+0x12/0x17
[ 1199.007160] INFO: task btrfs-transacti:965 blocked for more than 120 seconds.
[ 1199.008817]       Not tainted 3.19.2-1-ARCH #1
[ 1199.010464] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 1199.012299] btrfs-transacti D ffff88014d96fd98     0   965      2 0x00000000
[ 1199.012325]  ffff88014d96fd98 ffff8802147727c0 0000000000013f00 ffff88014d96ffd8
[ 1199.012330]  0000000000013f00 ffffffff81818540 ffff8802147727c0 ffff880207a4ffc8
[ 1199.012335]  ffff88017a3e2000 ffff880100000000 ffff88017a3e2000 ffff880100000033
[ 1199.012341] Call Trace:
[ 1199.012350]  [<ffffffff811b5d1a>] ? kmem_cache_alloc+0x16a/0x180
[ 1199.012367]  [<ffffffffa08f27ca>] ? btrfs_free_path+0x2a/0x40 [btrfs]
[ 1199.012384]  [<ffffffffa0976213>] ? __btrfs_run_delayed_items+0xf3/0x1d0 [btrfs]
[ 1199.012391]  [<ffffffff8155e999>] schedule+0x29/0x70
[ 1199.012408]  [<ffffffffa091d555>] btrfs_commit_transaction+0x2a5/0xbe0 [btrfs]
[ 1199.012413]  [<ffffffff810b4380>] ? wait_woken+0x90/0x90
[ 1199.012429]  [<ffffffffa0918fc5>] transaction_kthread+0x1d5/0x240 [btrfs]
[ 1199.012446]  [<ffffffffa0918df0>] ? btrfs_cleanup_transaction+0x5a0/0x5a0 [btrfs]
[ 1199.012453]  [<ffffffff81091748>] kthread+0xd8/0xf0
[ 1199.012459]  [<ffffffff81091670>] ? kthread_create_on_node+0x1c0/0x1c0
[ 1199.012465]  [<ffffffff81562758>] ret_from_fork+0x58/0x90
[ 1199.012471]  [<ffffffff81091670>] ? kthread_create_on_node+0x1c0/0x1c0