[23084.426006] sysrq: SysRq : Show Blocked State [23084.426085] task PC stack pid father [23084.426332] mount D 0 4857 4618 0x00000080 [23084.426403] Call Trace: [23084.426531] ? __schedule+0x2c3/0x830 [23084.426628] ? __wake_up_common+0x6f/0x120 [23084.426751] schedule+0x2d/0x90 [23084.426871] wait_current_trans+0x98/0xc0 [23084.426953] ? wait_woken+0x80/0x80 [23084.427058] start_transaction+0x2e9/0x3e0 [23084.427128] btrfs_drop_snapshot+0x48c/0x860 [23084.427220] merge_reloc_roots+0xca/0x210 [23084.427277] btrfs_recover_relocation+0x290/0x420 [23084.427399] ? btrfs_cleanup_fs_roots+0x174/0x190 [23084.427533] open_ctree+0x2158/0x2549 [23084.427592] ? bdi_register_va.part.2+0x10a/0x1a0 [23084.427652] btrfs_mount_root+0x678/0x730 [23084.427709] ? pcpu_next_unpop+0x32/0x40 [23084.427797] ? pcpu_alloc+0x2f6/0x680 [23084.427884] ? mount_fs+0x30/0x150 [23084.427939] ? btrfs_decode_error+0x20/0x20 [23084.427996] mount_fs+0x30/0x150 [23084.428054] vfs_kern_mount.part.7+0x4f/0xf0 [23084.428111] btrfs_mount+0x156/0x8ad [23084.428167] ? pcpu_block_update_hint_alloc+0x15e/0x1d0 [23084.428226] ? pcpu_next_unpop+0x32/0x40 [23084.428282] ? pcpu_alloc+0x2f6/0x680 [23084.428338] ? mount_fs+0x30/0x150 [23084.428393] mount_fs+0x30/0x150 [23084.428450] vfs_kern_mount.part.7+0x4f/0xf0 [23084.428507] do_mount+0x5b0/0xc60 [23084.428563] ksys_mount+0x7b/0xd0 [23084.428618] __x64_sys_mount+0x1c/0x20 [23084.428676] do_syscall_64+0x55/0x110 [23084.428734] entry_SYSCALL_64_after_hwframe+0x49/0xbe [23084.428794] RIP: 0033:0x7efeb90daa1a [23084.428849] RSP: 002b:00007ffcc8b8fee8 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5 [23084.428925] RAX: ffffffffffffffda RBX: 000055d5bef05420 RCX: 00007efeb90daa1a [23084.428987] RDX: 000055d5bef05600 RSI: 000055d5bef05ab0 RDI: 000055d5bef05b70 [23084.429048] RBP: 0000000000000000 R08: 000055d5bef08e40 R09: 000000000000003f [23084.429109] R10: 00000000c0ed0000 R11: 0000000000000206 R12: 000055d5bef05b70 [23084.429170] R13: 000055d5bef05600 R14: 0000000000000000 R15: 00000000ffffffff
On Fri, Aug 10, 2018 at 3:40 AM, Dan Merillat <dan.meril...@gmail.com> wrote: > Kernel 4.17.9, 11tb BTRFS device (md-backed, not btrfs raid) > > I was testing something out and enabled quota groups and started getting > 2-5 minute long pauses where a btrfs-transaction thread spun at 100%. > > Post-reboot the mount process spinds at 100% CPU, occasinally yielding > to a btrfs-transaction thread at 100% CPU. The switchover is marked > by a burst of disk activity in btrace. > > Btrace shows all disk activity is returning promptly - no hanging submits. > > Currently the mount is at 6+ hours. > > Suggestions on how to go about debugging this?
