mount hangs, have a backtrace

[prometheanfire]

happened while running 'mount -t zfs -o rw,zfsutil node02-zp00/ROOT/rootfs /mnt'

SysRq : Show Blocked State
task PC stack pid father
zfs_iput_taskq/ D ffff8806015a0ac0 0 3815 2 0x00000000
ffff88061c86d978 0000000000000046 ffffffff810e0599 000000000000e540
ffff88062662e440 ffff88061cdcc400 0000000000020000 ffff88061fd8b000
0000000000000000 8000000000000000 ffff880608995538 ffff880608995538
Call Trace:
[] ? enqueue_task_fair+0x125/0x125
[] ? __mutex_lock_slowpath+0x21b/0x230
[] schedule+0x5f/0x67
[] io_schedule+0x91/0xdd
[] cv_wait_common+0xa0/0x14e
[] ? abort_exclusive_wait+0x92/0x92
[] __cv_wait_io+0x27/0x2f
[] zio_wait+0x17f/0x1ca
[] dbuf_read+0x552/0x71e
[] ? dbuf_hold_impl+0x87/0x9f
[] dnode_hold_impl+0x1f3/0x51a
[] dnode_hold+0x31/0x3e
[] dmu_object_info+0x2e/0x68
[] zfs_unlinked_drain+0x4c/0xdc
[] ? idle_balance+0xd7/0x108
[] ? __schedule+0x870/0x918
[] ? enqueue_task_fair+0x125/0x125
[] ? autoremove_wake_function+0x28/0x54
[] ? atomic_notifier_call_chain+0x2b/0x38
[] taskq_thread+0x1ed/0x31e
[] ? try_to_wake_up+0x244/0x244
[] ? task_done+0xa1/0xa1
[] kthread+0xc1/0xc9
[] ? kthread_freezable_should_stop+0x4e/0x4e
[] ret_from_fork+0x72/0xa0
[] ? kthread_freezable_should_stop+0x4e/0x4e
mount D ffff88063f66e540 0 3826 3458 0x00000000
ffff88061f953488 0000000000000086 ffffffff810e0599 000000000000e540
ffff880626a2f5a0 ffff88061d0498a0 0000000000020000 ffff88061fd8b000
0000000000000000 8000000000000000 ffff8806183743f8 ffff8806183743f8
Call Trace:
[] ? enqueue_task_fair+0x125/0x125
[] ? __mutex_lock_slowpath+0x21b/0x230
[] schedule+0x5f/0x67
[] io_schedule+0x91/0xdd
[] cv_wait_common+0xa0/0x14e
[] ? abort_exclusive_wait+0x92/0x92
[] __cv_wait_io+0x27/0x2f
[] zio_wait+0x17f/0x1ca
[] dbuf_read+0x552/0x71e
[] ? dbuf_hold_impl+0x87/0x9f
[] dmu_buf_hold+0x14e/0x1a0
[] zap_lockdir+0x4c/0x53a
[] zap_count+0x39/0x75
[] ? __mutex_lock_slowpath+0x21b/0x230
[] zfs_rmnode+0x5d/0x2f6
[] zfs_zinactive+0x122/0x15c
[] zfs_inactive+0x19e/0x242
[] zpl_evict_inode+0x23/0x2d
[] ? zpl_put_super+0x1d/0x1d
[] evict+0xb3/0x16f
[] iput+0x134/0x143
[] zfs_rmnode+0x2e1/0x2f6
[] zfs_zinactive+0x122/0x15c
[] zfs_inactive+0x19e/0x242
[] zpl_evict_inode+0x23/0x2d
[] ? zpl_put_super+0x1d/0x1d
[] evict+0xb3/0x16f
[] iput+0x134/0x143
[] zfs_unlinked_drain+0xa3/0xdc
[] ? try_to_wake_up+0x22c/0x244
[] ? finish_wait+0x62/0x73
[] ? taskq_create+0x36c/0x394
[] zfs_sb_setup+0x112/0x195
[] zfs_domount+0x253/0x2d4
[] ? sget+0x56d/0x58e
[] ? zpl_mount+0x46/0x46
[] zpl_fill_super+0x23/0x2d
[] ? zpl_mount+0x46/0x46
[] mount_nodev+0x5a/0xa5
[] zpl_mount+0x37/0x46
[] mount_fs+0x71/0x160
[] vfs_kern_mount+0x69/0xf7
[] do_mount+0x75a/0x8ef
[] ? retint_restore_args+0x6/0xd
[] ? __get_user_1+0x25/0x40
[] sys_mount+0x86/0xc6
[] system_call_fastpath+0x18/0x1d

[behlendorf]

It's hung waiting on a read, why isn't exactly clear. Were there disk troubles?

[prometheanfire]

No disk troubles. I think the current theory was that it's waiting on something that deadlocked.

[FransUrbo]

@prometheanfire Is this still a problem with latest HEAD?

[prometheanfire]

no, I'll reopen if it's an actual problem