[lustre-discuss] Connectivity issues after client crash

[Nehring, Shane R [ITS]]

Hello Jesse,

What I think we may have been hitting in this particular case was
https://jira.whamcloud.com/browse/LU-16349 which we in the short term worked
around by switching to ksocklnd from o2iblnd, and then ultimately mostly moved
away from omnipath to ib.

I've seen some weird behavior in our environment around peer discovery (we have
tcp and o2ib nids on the oss and mds nodes to provide access over both methods)
that've caused problems in the past, such that we just outright disable peer
discovery with modprobe (eg options lnet lnet_peer_discovery_disabled=1 in
/etc/modprobe.d/lnet.conf). I dunno if you've tried that yet, but if not it
might be a place to start (assuming you don't need automatic multi-rail)

Shane

On Tue, 2024-12-03 at 20:29 +0000, Jesse Stroik wrote:
> Hi Shane,
> 
> I realize this is quite an old post but I think it is worth responding for
> posterity and because I suspect others who upgrade may run into this issue.
> 
> I'm observing some similar issues to what you describe. They started this
> weekend for us on two of our servers which were upgraded to rocky 8 and lustre
> 2.15.5 a couple of months ago. Like you, we run infiniband. We also route to
> ethernet clients and our lustre routers are now running rocky 8 and either
> lustre 2.15.5 or 2.15.3.
> 
> The behavior that we observe is widely similar to yours though we have a few
> observations that may be relevant. I suspect that if we can limit the
> infiniband communication to certain segments or LIDs it seems to behave fine.
> 
> Today i was able to reproduce the problem when routing to an ethernet client
> that ran our robinhood policy engine. With the file systems behaving normally
> to our infiniband network clients, I enabled routing on them again and tested
> with all lrouters enabled or just individual lrouters enabled. In all cases
> that i tested, mounting one of those file systems resulted in the
> communication problems on the MDS and OSS servers for that file system. In one
> case an MDS panicked as soon as that client mounted its file system. I put an
> IB card into that policy engine client, removed all lnet routing for those
> file systems and lnet behavior was stable with that client mounting those file
> systems and ingesting the changelogs.
> 
> When the servers have failed lnet communication, they can sometimes be fixed
> by stopping the lustre service / unmounting the OSTs and MDTs and restarting /
> reconfiguring lnet. If i'm unable to do that, rebooting the affected systems
> seems to be the only solution and they sometimes hang indefinitely trying to
> shut down lnet necessitating a power cycle.
> 
> When the issue first started I did suspect the infiniband fabric and looked
> for problems with that, though, like you, I didn't find anything conclusive. A
> recent change we've had is our OpenSM subnet manager definitely restarted and
> moved when we updated the kernel and lustre-client versions on two of our
> lrouters. However, even when lnet is unable to communicate, the nodes can all
> still ping each other with ipv4 ping IPoIB which suggests the subnet manager
> and infiniband are working.
> 
> I did also attempt manual lnet peer discovery on individual systems while they
> were affected to see if i could recover them that way. Discovery failed on
> those systems, but only when we were already observing the communication
> problem with lnet.
> 
> Jesse
> 
> ________________________________________
> From: lustre-discuss <lustre-discuss-bounces at lists.lustre.org> on behalf of
> Nehring, Shane R [LAS] via lustre-discuss <lustre-discuss at lists.lustre.org>
> Sent: Wednesday, December 21, 2022 11:49 AM
> To: lustre-discuss at lists.lustre.org
> Subject: [lustre-discuss] Connectivity issues after client crash
> 
> Hello all,
> 
> I'm hoping that someone might be able to help me with an issue I've been
> seeing
> periodically since updating to 2.15.x.
> 
> Back in July we remade our scratch storage volume with 2.15 after running 2.12
> for a long time. As part of the upgrade we reinstalled our oss and mds nodes
> with rhel 8 so we'd finally be able to take advantage of project quotas. For
> background, our nodes are connected via omnipath and we have a mix of el7
> clients, el8 clients, and el9 clients. We've been piecemeal updating our
> clients
> to el9 over the past few months with the goal of being 99% el9 clients by mid
> January.
> 
> Since upgrading we've seen recurring connectivity issues arise in the cluster
> from time to time which seem to be very strongly correlated with a client
> crashing. The fabric itself seems fine. There's no evidence of error or any
> packet loss, so I cannot confidently blame it.
> 
> On an oss that's having trouble communicating we see the following messages
> for
> various osts:
> 
> kernel: LNetError: 31282:0:(o2iblnd_cb.c:3358:kiblnd_check_txs_locked()) Timed
> out tx: active_txs(WSQ:100), 19 seconds
> kernel: LNetError: 31282:0:(o2iblnd_cb.c:3358:kiblnd_check_txs_locked())
> Skipped
> 6 previous similar messages
> kernel: LNetError: 31282:0:(o2iblnd_cb.c:3428:kiblnd_check_conns()) Timed out
> RDMA with 172.16.100.19 at o2ib (4): c: 31, oc: 0, rc: 31
> kernel: LNetError: 31282:0:(o2iblnd_cb.c:3428:kiblnd_check_conns()) Skipped 6
> previous similar messages
> kernel: LustreError: 109351:0:(ldlm_lib.c:3543:target_bulk_io()) @@@ network
> error on bulk WRITE  req at 00000000f848e208 x1751146351599040/t0(0) o4-
> > 10ccde33-01ef-47cf-873d-da9a1b6bb1ea at 172.16.100.19@o2ib:19/0 lens 488/448 e
> > 0
> to 0 dl 1671634949 ref 1 fl Interpret:/2/0 rc 0/0 job:'873032'
> kernel: Lustre: work-OST0007: Bulk IO write error with 10ccde33-01ef-47cf-
> 873d-
> da9a1b6bb1ea (at 172.16.100.19 at o2ib), client will retry: rc = -110
> kernel: Lustre: Skipped 5 previous similar messages
> kernel: LustreError: 109351:0:(ldlm_lib.c:3543:target_bulk_io()) @@@ network
> error on bulk WRITE  req at 000000008176189a x1751153771751616/t0(0) o4-
> > 63e88958-d0b1-4c7f-8413-da96b181cd92 at 172.16.100.25@o2ib:94/0 lens 488/448 e
> > 0
> to 0 dl 1671635024 ref 1 fl Interpret:/0/0 rc 0/0 job:'873641'
> Lustre: work-OST000d: Bulk IO write error with 63e88958-d0b1-4c7f-8413-
> da96b181cd92 (at 172.16.100.25 at o2ib), client will retry: rc = -110
> 
> An already connected client will see messages along the lines of:
> 
> kernel: Lustre: 3736:0:(client.c:2295:ptlrpc_expire_one_request()) @@@ Request
> sent has timed out for slow reply: [sent 1671634931/real 1671634931]
> req at ffff94a0ed490000 x1751139078233344/t0(0) o9-
> > work-OST0001-osc-ffff95552570a000 at 172.16.100.253@o2ib:28/4 lens 224/224 e 0
> > to
> 1
> 
> A stack trace on one of the clients of an ls against the volume that hangs:
> 
> [<ffffffffc1576d05>] cl_sync_io_wait+0x1c5/0x480 [obdclass]
> [<ffffffffc1572943>] cl_lock_request+0x1d3/0x210 [obdclass]
> [<ffffffffc17db1d9>] cl_glimpse_lock+0x329/0x380 [lustre]
> [<ffffffffc17db5a5>] cl_glimpse_size0+0x255/0x280 [lustre]
> [<ffffffffc1793cdc>] ll_getattr_dentry+0x50c/0x9c0 [lustre]
> [<ffffffffc17941ae>] ll_getattr+0x1e/0x20 [lustre]
> [<ffffffff99a53d49>] vfs_getattr+0x49/0x80
> [<ffffffff99a53e55>] vfs_fstatat+0x75/0xc0
> [<ffffffff99a54261>] SYSC_newlstat+0x31/0x60
> [<ffffffff99a546ce>] SyS_newlstat+0xe/0x10
> [<ffffffff99f99f92>] system_call_fastpath+0x25/0x2a
> [<ffffffffffffffff>] 0xffffffffffffffff
> 
> If we try to reboot a client to clear the issue it won't be able to mount the
> filesystem; the mount process hangs in D until it times out. A stack trace
> from
> the mount:
> [<0>] llog_process_or_fork+0x2de/0x570 [obdclass]
> [<0>] llog_process+0x10/0x20 [obdclass]
> [<0>] class_config_parse_llog+0x1eb/0x3e0 [obdclass]
> [<0>] mgc_process_cfg_log+0x659/0xc90 [mgc]
> [<0>] mgc_process_log+0x667/0x800 [mgc]
> [<0>] mgc_process_config+0x42b/0x6e0 [mgc]
> [<0>] obd_process_config.constprop.0+0x76/0x1a0 [obdclass]
> [<0>] lustre_process_log+0x562/0x8f0 [obdclass]
> [<0>] ll_fill_super+0x6ec/0x1020 [lustre]
> [<0>] lustre_fill_super+0xe4/0x470 [lustre]
> [<0>] mount_nodev+0x41/0x90
> [<0>] legacy_get_tree+0x24/0x40
> [<0>] vfs_get_tree+0x22/0xb0
> [<0>] do_new_mount+0x176/0x310
> [<0>] __x64_sys_mount+0x103/0x140
> [<0>] do_syscall_64+0x38/0x90
> [<0>] entry_SYSCALL_64_after_hwframe+0x44/0xae
> 
> 
> When this has happened in the past we've had to shut down the entire lustre
> backend, and if we're lucky clients would start recovering once everything was
> back up again. The last time this happened we actually had to shut down the
> entire cluster.
> 
> In this particular case rebooting the osses and mds/mgs has stopped the errors
> on the server side, but el9 and el8 clients are now seeing:
> 
> kernel: LNetError: 149017:0:(o2iblnd_cb.c:966:kiblnd_post_tx_locked()) Error -
> 22
> posting transmit to 172.16.100.250 at o2ib
> kernel: LNetError: 149017:0:(o2iblnd_cb.c:966:kiblnd_post_tx_locked()) Skipped
> 31 previous similar messages
> and
> LustreError: 3585788:0:(file.c:5096:ll_inode_revalidate_fini()) work:
> revalidate
> FID [0x200000007:0x1:0x0] error: rc = -4
> 
> el7 clients have recovered seemingly without issue.
> 
> Wondering if anyone might have any suggestions on where to look as to why this
> is breaking, or pointers as to how to recover from this situation without
> rebooting if possible.
> 
> 
> 
> _______________________________________________
> lustre-discuss mailing list
> lustre-discuss at lists.lustre.org
> http://lists.lustre.org/listinfo.cgi/lustre-discuss-lustre.org

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