The kernel thread is spending a lot of time in handle_active_stripes but
not staying in there since I see it calling handle_stripe and then I
also see calls to __release_stripe then back to handle_stripe again. So,
it's clearly exiting handle_active_stripes but getting dumped right back
in there. Presumably, handle_active_stripes is not completing the
necessary work and the kernel thread keeps calling it expecting the
pending work to be completed.
When the system boots up an mdadm process runs at near 100% CPU with
sporadic reads of the journal device. After ~30s or so, the IO stops,
the mdadm process disappears, and the mdX_raid6 kernel thread starts
taking 100% CPU.
RIP: 0010:do_release_stripe+0x52/0x410 [raid456]
RSP: 0018:ffffbb7d41dcbcc0 EFLAGS: 00000017
RAX: 0000000002000000 RBX: ffff8f10c819bf20 RCX: 0000000000000000
RDX: 0000000000000002 RSI: ffff8f10c819bf20 RDI: ffff8f114a2ad400
RBP: ffffbb7d41dcbce8 R08: ffff8f113e3dd888 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000000 R12: ffff8f10c819bf30
R13: ffff8f113e3ddb58 R14: ffff8f113e3dd800 R15: 0000000000000003
FS: 0000000000000000(0000) GS:ffff8f115ed40000(0000)
knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb7675e1000 CR3: 0000000412cf5000 CR4: 00000000000406e0
Call Trace:
__release_stripe+0x16/0x20 [raid456]
handle_active_stripes.isra.60+0x44e/0x5a0 [raid456]
raid5d+0x42e/0x630 [raid456]
--Larkin
On 11/24/2017 2:20 PM, Larkin Lowrey wrote:
After hard-rebooting, this instance (stripe_cache_active: 2) assembled
just fine on boot. The next time I encountered this the array was
'inactive' on boot. There was a flurry of I/O initially (which seems
to indicate journal re-play, then the array becoming 'active') but the
I/O ceased without the array becoming active.
This time...
stripe_cache_active: 2376
md125 : inactive md127p4[9](J) sdk1[2] sdl1[3] sdn1[5] sdo1[6]
sdm1[4] sdj1[1] sdq1[8] sdp1[7]
31258219068 blocks super 1.2
# mdadm -D /dev/md125
/dev/md125:
Version : 1.2
Creation Time : Thu Oct 19 10:11:35 2017
Raid Level : raid6
Used Dev Size : 18446744073709551615
Raid Devices : 8
Total Devices : 9
Persistence : Superblock is persistent
Update Time : Fri Nov 24 13:41:38 2017
State : active, FAILED, Not Started
Active Devices : 8
Working Devices : 9
Failed Devices : 0
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 64K
Consistency Policy : journal
Name : ########:3
UUID : de6a2ce0:1a4c510f:d7c89da4:1215a312
Events : 156844
Number Major Minor RaidDevice State
- 0 0 0 removed
- 0 0 1 removed
- 0 0 2 removed
- 0 0 3 removed
- 0 0 4 removed
- 0 0 5 removed
- 0 0 6 removed
- 0 0 7 removed
- 259 3 - spare /dev/md127p4
- 8 225 5 sync /dev/sdo1
- 8 209 4 sync /dev/sdn1
- 8 193 3 sync /dev/sdm1
- 8 177 2 sync /dev/sdl1
- 8 161 1 sync /dev/sdk1
- 8 145 0 sync /dev/sdj1
- 65 1 7 sync /dev/sdq1
- 8 241 6 sync /dev/sdp1
--Larkin
On 11/23/2017 1:22 PM, Larkin Lowrey wrote:
Sometimes, stopping a raid6 array (with journal) hangs, the mdX_raid6
process pegs at 100% CPU, and there is no I/O. Looks like it's stuck
in an infinite loop.
Kernel: 4.13.13-200.fc26.x86_64
The stack trace (echo l > /proc/sysrq-trigger) is always the same:
handle_stripe+0x10c/0x2140 [raid456]
? pick_next_task_fair+0x491/0x550
handle_active_stripes.isra.60+0x3e5/0x5a0 [raid456]
raid5d+0x42e/0x630 [raid456]
? prepare_to_wait_event+0x79/0x160
md_thread+0x125/0x170
? md_thread+0x125/0x170
? finish_wait+0x80/0x80
kthread+0x125/0x140
? state_show+0x2f0/0x2f0
? kthread_park+0x60/0x60
? do_syscall_64+0x67/0x140
ret_from_fork+0x25/0x30
The array is healthy, has a journal, and writes were idle for several
minutes prior to running 'mdadm --stop'.
md124 : active raid6 sdt1[6] sds1[5] sdw1[1] sdx1[2] sdy1[3] sdu1[7]
sdv1[8] sdz1[4] md125p4[9](J)
23442092928 blocks super 1.2 level 6, 64k chunk, algorithm 2
[8/8] [UUUUUUUU]
stripe_cache_active: 2
stripe_cache_size: 32768
array_state: write-pending
journal_mode: write-through [write-back]
consistency_policy: journal
--Larkin
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
