[lustre-discuss] Repeated ZFS panics on MDT

Mountford, Christopher J. (Dr.) cjm14 at leicester.ac.uk
Wed Mar 15 13:35:43 PDT 2023


The ZFS scrub completed without any errors/corrections.

Following the scrub (and clearing all users from our cluster login nodes) I remounted the MDT and it appears to be running fine (just running the remaining batch jobs). I'm now able to get onto our monitoring system - hopefully a look at the lustre jobstats might reveal if there was unusually high filesystem load.

zpool status following scrub:

[root at amds01b ~]# zpool status
  pool: ahomemdt00
 state: ONLINE
  scan: scrub repaired 0B in 0h36m with 0 errors on Wed Mar 15 20:16:53 2023
config:

        NAME                  STATE     READ WRITE CKSUM
        ahomemdt00            ONLINE       0     0     0
          mirror-0            ONLINE       0     0     0
            A12-amds01j1-001  ONLINE       0     0     0
            A12-amds01j1-002  ONLINE       0     0     0
          mirror-1            ONLINE       0     0     0
            A12-amds01j1-003  ONLINE       0     0     0
            A12-amds01j1-004  ONLINE       0     0     0
          mirror-2            ONLINE       0     0     0
            A12-amds01j1-005  ONLINE       0     0     0
            A12-amds01j1-006  ONLINE       0     0     0
          mirror-3            ONLINE       0     0     0
            A12-amds01j1-007  ONLINE       0     0     0
            A12-amds01j1-008  ONLINE       0     0     0
          mirror-4            ONLINE       0     0     0
            A12-amds01j1-009  ONLINE       0     0     0
            A12-amds01j1-010  ONLINE       0     0     0

errors: No known data errors
[root at amds01b ~]#

We did see the following error in the MDS syslog after the lustre recovery completed (Mar 15 20:19:55 amds01b kernel: LustreError: 6052:0:(mdd_orphans.c:375:mdd_orphan_key_test_and_delete()) ahome3-MDD0000: error unlinking orphan [0x20001bb76:0xd86e:0x0]: rc = -2) - not sure if this could be related to the problem.

We also had one login node locked up with a load of >4000 and many ps commands uninterruptible and hung. Again, not sure if this could be a cause of the problems we have been seeing.

Kind Regards,
Christopher.

________________________________________
From: lustre-discuss <lustre-discuss-bounces at lists.lustre.org> on behalf of Mountford, Christopher J. (Dr.) via lustre-discuss <lustre-discuss at lists.lustre.org>
Sent: 15 March 2023 19:21
To: Colin Faber
Cc: lustre-discuss
Subject: Re: [lustre-discuss] Repeated ZFS panics on MDT

***CAUTION:*** This email was sent from an EXTERNAL source. Think before clicking links or opening attachments.

Hi Colin,

Not yet, we last scrubbed the pool ~2 weeks ago when we first saw this problem. I've got a few additional tests to run now to see if we can track the cause to a particular job/process, but kicking off a scrub is my next thing to do (It should only take ~40 minutes, it's a fairly small ssd based MDT).

Thanks,
Chris

________________________________________
From: Colin Faber <cfaber at gmail.com>
Sent: 15 March 2023 18:41
To: Mountford, Christopher J. (Dr.)
Cc: lustre-discuss
Subject: Re: [lustre-discuss] Repeated ZFS panics on MDT

***CAUTION:*** This email was sent from an EXTERNAL source. Think before clicking links or opening attachments.
Have you tried resilvering the pool?

On Wed, Mar 15, 2023, 11:57 AM Mountford, Christopher J. (Dr.) via lustre-discuss <lustre-discuss at lists.lustre.org<mailto:lustre-discuss at lists.lustre.org>> wrote:
I'm hoping someone offer some suggestions.

We have a problem on our production Lustre/ZFS filesystem (CentOS 7, ZFS 0.7.13, Lustre 2.12.9), so far I've drawn a blank trying to track down the cause of this.

We see the following zfs panic message in the logs (in every case the VERIFY3/panic lines are identical):


Mar 15 17:15:39 amds01a kernel: VERIFY3(sa.sa_magic == 0x2F505A) failed (8 == 3100762)
Mar 15 17:15:39 amds01a kernel: PANIC at zfs_vfsops.c:584:zfs_space_delta_cb()
Mar 15 17:15:39 amds01a kernel: Showing stack for process 15381
Mar 15 17:15:39 amds01a kernel: CPU: 31 PID: 15381 Comm: mdt00_020 Tainted: P           OE  ------------   3.10.0-1160.49.1.el7_lustre.x86_64 #1
Mar 15 17:15:39 amds01a kernel: Hardware name: HPE ProLiant DL360 Gen10/ProLiant DL360 Gen10, BIOS U32 02/09/2023
Mar 15 17:15:39 amds01a kernel: Call Trace:
Mar 15 17:15:39 amds01a kernel: [<ffffffff99d83539>] dump_stack+0x19/0x1b
Mar 15 17:15:39 amds01a kernel: [<ffffffffc0b76f24>] spl_dumpstack+0x44/0x50 [spl]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc0b76ff9>] spl_panic+0xc9/0x110 [spl]
Mar 15 17:15:39 amds01a kernel: [<ffffffff996e482c>] ? update_curr+0x14c/0x1e0
Mar 15 17:15:39 amds01a kernel: [<ffffffff99707cf4>] ? getrawmonotonic64+0x34/0xc0
Mar 15 17:15:39 amds01a kernel: [<ffffffffc0c87aa3>] ? dmu_zfetch+0x393/0x520 [zfs]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc0c6a073>] ? dbuf_rele_and_unlock+0x283/0x4c0 [zfs]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc0b78ff1>] ? __cv_init+0x41/0x60 [spl]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc0d0f53c>] zfs_space_delta_cb+0x9c/0x200 [zfs]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc0c7a944>] dmu_objset_userquota_get_ids+0x154/0x440 [zfs]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc0c89e98>] dnode_setdirty+0x38/0xf0 [zfs]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc0c8a21c>] dnode_allocate+0x18c/0x230 [zfs]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc0c76d2b>] dmu_object_alloc_dnsize+0x34b/0x3e0 [zfs]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc1d73052>] __osd_object_create+0x82/0x170 [osd_zfs]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc1d7ce23>] ? osd_declare_xattr_set+0xb3/0x190 [osd_zfs]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc1d733bd>] osd_mkreg+0x7d/0x210 [osd_zfs]
Mar 15 17:15:39 amds01a kernel: [<ffffffff99828f01>] ? __kmalloc_node+0x1d1/0x2b0
Mar 15 17:15:39 amds01a kernel: [<ffffffffc1d6f8f6>] osd_create+0x336/0xb10 [osd_zfs]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc2016fb5>] lod_sub_create+0x1f5/0x480 [lod]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc2007729>] lod_create+0x69/0x340 [lod]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc1d65690>] ? osd_trans_create+0x410/0x410 [osd_zfs]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc2081993>] mdd_create_object_internal+0xc3/0x300 [mdd]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc206aa4b>] mdd_create_object+0x7b/0x820 [mdd]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc2074fd8>] mdd_create+0xdd8/0x14a0 [mdd]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc1f0e118>] mdt_reint_open+0x2588/0x3970 [mdt]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc16f82b9>] ? check_unlink_entry+0x19/0xd0 [obdclass]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc1eede52>] ? ucred_set_audit_enabled.isra.15+0x22/0x60 [mdt]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc1f00f23>] mdt_reint_rec+0x83/0x210 [mdt]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc1edc413>] mdt_reint_internal+0x6e3/0xaf0 [mdt]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc1ee8ec6>] ? mdt_intent_fixup_resent+0x36/0x220 [mdt]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc1ee9132>] mdt_intent_open+0x82/0x3a0 [mdt]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc1edf74a>] mdt_intent_opc+0x1ba/0xb50 [mdt]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc1a0d6c0>] ? lustre_swab_ldlm_policy_data+0x30/0x30 [ptlrpc]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc1ee90b0>] ? mdt_intent_fixup_resent+0x220/0x220 [mdt]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc1ee79e4>] mdt_intent_policy+0x1a4/0x360 [mdt]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc19bc4e6>] ldlm_lock_enqueue+0x376/0x9b0 [ptlrpc]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc10a22b7>] ? cfs_hash_bd_add_locked+0x67/0x90 [libcfs]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc10a5a4e>] ? cfs_hash_add+0xbe/0x1a0 [libcfs]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc19e3aa6>] ldlm_handle_enqueue0+0xa86/0x1620 [ptlrpc]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc1a0d740>] ? lustre_swab_ldlm_lock_desc+0x30/0x30 [ptlrpc]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc1a6d092>] tgt_enqueue+0x62/0x210 [ptlrpc]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc1a73eea>] tgt_request_handle+0xada/0x1570 [ptlrpc]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc1a4d601>] ? ptlrpc_nrs_req_get_nolock0+0xd1/0x170 [ptlrpc]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc1096bde>] ? ktime_get_real_seconds+0xe/0x10 [libcfs]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc1a18bcb>] ptlrpc_server_handle_request+0x24b/0xab0 [ptlrpc]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc1a156e5>] ? ptlrpc_wait_event+0xa5/0x360 [ptlrpc]
Mar 15 17:15:39 amds01a kernel: [<ffffffff99d7dcf3>] ? queued_spin_lock_slowpath+0xb/0xf
Mar 15 17:15:39 amds01a kernel: [<ffffffff99d8baa0>] ? _raw_spin_lock+0x20/0x30
Mar 15 17:15:39 amds01a kernel: [<ffffffffc1a1c534>] ptlrpc_main+0xb34/0x1470 [ptlrpc]
Mar 15 17:15:39 amds01a kernel: [<ffffffffc1a1ba00>] ? ptlrpc_register_service+0xf80/0xf80 [ptlrpc]
Mar 15 17:15:39 amds01a kernel: [<ffffffff996c5e61>] kthread+0xd1/0xe0
Mar 15 17:15:39 amds01a kernel: [<ffffffff996c5d90>] ? insert_kthread_work+0x40/0x40
Mar 15 17:15:39 amds01a kernel: [<ffffffff99d95ddd>] ret_from_fork_nospec_begin+0x7/0x21
Mar 15 17:15:39 amds01a kernel: [<ffffffff996c5d90>] ? insert_kthread_work+0x40/0x40

At this point all ZFS I/O freezes completely and the MDS has to be fenced. This has happened ~4 times in the last hour.

I'm at a loss how to correct this - I'm currently thinking that we may have to rebuild and recover our entire filesystem from backups (thankfully this is our home file system which is small and entirely ssd based, so should not take to long to recover).

May be related to this: https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugs.freebsd.org%2Fbugzilla%2Fshow_bug.cgi%3Fid%3D216586&data=05%7C01%7Ccjm14%40leicester.ac.uk%7Cf1aecc6fca1d48a1b27808db258ad434%7Caebecd6a31d44b0195ce8274afe853d9%7C0%7C0%7C638145050417993109%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=E7U0mzfO%2BIsJy%2BWJxzWqw8MSJynZXH2jTAGMjQQxIIE%3D&reserved=0<https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugs.freebsd.org%2Fbugzilla%2Fshow_bug.cgi%3Fid%3D216586&data=05%7C01%7Ccjm14%40leicester.ac.uk%7Cf1aecc6fca1d48a1b27808db258ad434%7Caebecd6a31d44b0195ce8274afe853d9%7C0%7C0%7C638145050417993109%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=E7U0mzfO%2BIsJy%2BWJxzWqw8MSJynZXH2jTAGMjQQxIIE%3D&reserved=0> bug seen on freebsd (with a much more recent ZFS version).

The problem was first seen 3 weeks ago, but went away after a couple of reboots. This time it seems to be more serious.

Kind Regards,
Christopher.

------------------------------------
Dr. Christopher Mountford,
System Specialist,
RCS,
Digital Services,
University Of Leicester.
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