> On Jun 8, 2020, at 8:34 AM, Robert Milkowski <rmilkowski@xxxxxxxxx> wrote:
>
> Hi,
>
> We see random nfsv4.0 Linux clients ending stuck on accessing an nfs server
> which was just failover. Specifically this happens with NetApps during ONTAP
> upgrades.
> An affected client has all i/o stuck against the specific nfs server, while
> accessing other nfs servers is fine. Rebooting the client fixes the issue.
>
>
> This weekend, it happened again and I managed to do some debugging.
>
> btw: I anonymized/changed some data below (hostnames, IP addresses, etc.)
>
> The affected client was sending RENEW operation against NetApp which was
> updated, getting NFS4ERR_STALE_CLIENTID in response, but then the client
> was not trying to recover (setclientid, etc.) instead it just sent another
> RENEW op, and that continued like this in a loop:
>
> [root@client root]# tshark -Y nfs host BADnfssrv1
> Running as user "root" and group "root". This could be dangerous.
> Capturing on 'eth0'
> 1 0.000000000 10.100.139.63 -> 10.200.0.10 NFS 230 V4 Call RENEW CID:
> 0xddb4
> 2 0.074544014 10.200.0.10 -> 10.100.139.63 NFS 182 V4 Reply (Call In 1)
> RENEW Status: NFS4ERR_STALE_CLIENTID
> 5 5.087870527 10.100.139.63 -> 10.200.0.10 NFS 230 V4 Call RENEW CID:
> 0xddb4
> 6 5.162370462 10.200.0.10 -> 10.100.139.63 NFS 182 V4 Reply (Call In 5)
> RENEW Status: NFS4ERR_STALE_CLIENTID
> 9 10.175844705 10.100.139.63 -> 10.200.0.10 NFS 230 V4 Call RENEW CID:
> 0xddb4
> 10 10.250376101 10.200.0.10 -> 10.100.139.63 NFS 182 V4 Reply (Call In 9)
> RENEW Status: NFS4ERR_STALE_CLIENTID
> 13 15.263984093 10.100.139.63 -> 10.200.0.10 NFS 230 V4 Call RENEW CID:
> 0xddb4
> 14 15.338614422 10.200.0.10 -> 10.100.139.63 NFS 182 V4 Reply (Call In 13)
> RENEW Status: NFS4ERR_STALE_CLIENTID
> ...
>
> Traffic to other nfs servers on the same client were working fine.
>
> There was a similar thread back in March reported here by James Pearson, see
> thread with subject "Stuck NFSv4 mounts of Isilon filer with repeated
> NFS4ERR_STALE_CLIENTID errors". I've managed to gather more data though, so
> hopefully this is going to be useful.
>
>
> This specific client is running:
>
> [root@client ~]$ cat /etc/redhat-release
> CentOS Linux release 7.3.1611 (Core)
>
> [root@client ~]$ uname -a
> Linux client.company.domain 3.10.0-693.11.6.el7.x86_64 #1 SMP Thu Jan 4
> 01:06:37 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
Hi Robert-
The usual course of action for bugs in distributor kernels is to work
directly with the distributor. Upstream developers don't generally have
access to or expertise with those code bases. 7.3 is an older kernel,
and it's possible that upstream has addressed this issue and CentOS
has pulled that fix into a newer release.
The troubleshooting below is common to this class of bugs. To get to
the root cause, you will need to observe the very beginning of the
loop, to see what condition triggers it.
> Although we hit the issue before on more recent centos versions as well.
>
> All nfs filesystems are mounted as with vers=4.0,sec=krb5
>
>
> An example process hanging, in this case df (collected via sysrq/t):
>
>
> Jun 6 19:31:35 client kernel: [10658517.222819] df D
> ffff8802173d1fa0 0 20131 19284 0x00000086
> Jun 6 19:31:35 client kernel: [10658517.222837] Call Trace:
> Jun 6 19:31:35 client kernel: [10658517.222868] [<ffffffff816ab6d9>]
> schedule+0x29/0x70
> Jun 6 19:31:35 client kernel: [10658517.222879] [<ffffffffc03367f8>]
> gss_cred_init+0x2b8/0x3f0 [auth_rpcgss]
> Jun 6 19:31:35 client kernel: [10658517.222885] [<ffffffff810b34b0>] ?
> wake_up_atomic_t+0x30/0x30
> Jun 6 19:31:35 client kernel: [10658517.222924] [<ffffffffc02eebe9>]
> rpcauth_lookup_credcache+0x219/0x2b0 [sunrpc]
> Jun 6 19:31:35 client kernel: [10658517.222989] [<ffffffffc0334623>]
> gss_lookup_cred+0x13/0x20 [auth_rpcgss]
> Jun 6 19:31:35 client kernel: [10658517.223150] [<ffffffffc02ee2db>]
> rpcauth_lookupcred+0x8b/0xd0 [sunrpc]
> Jun 6 19:31:35 client kernel: [10658517.223232] [<ffffffffc02ef0dd>]
> rpcauth_refreshcred+0x14d/0x1d0 [sunrpc]
> Jun 6 19:31:35 client kernel: [10658517.223285] [<ffffffffc02e299a>] ?
> xprt_lock_and_alloc_slot+0x6a/0x80 [sunrpc]
> Jun 6 19:31:35 client kernel: [10658517.223420] [<ffffffffc02dddf0>] ?
> call_bc_transmit+0x1b0/0x1b0 [sunrpc]
> Jun 6 19:31:35 client kernel: [10658517.223558] [<ffffffffc02dddf0>] ?
> call_bc_transmit+0x1b0/0x1b0 [sunrpc]
> Jun 6 19:31:35 client kernel: [10658517.223627] [<ffffffffc02de320>] ?
> call_retry_reserve+0x60/0x60 [sunrpc]
> Jun 6 19:31:35 client kernel: [10658517.223721] [<ffffffffc02de320>] ?
> call_retry_reserve+0x60/0x60 [sunrpc]
> Jun 6 19:31:35 client kernel: [10658517.223779] [<ffffffffc02de35c>]
> call_refresh+0x3c/0x60 [sunrpc]
> Jun 6 19:31:35 client kernel: [10658517.223821] [<ffffffffc02ec017>]
> __rpc_execute+0x97/0x410 [sunrpc]
> Jun 6 19:31:35 client kernel: [10658517.223827] [<ffffffff810b3475>] ?
> wake_up_bit+0x25/0x30
> Jun 6 19:31:35 client kernel: [10658517.223867] [<ffffffffc02ed7b8>]
> rpc_execute+0x68/0xb0 [sunrpc]
> Jun 6 19:31:35 client kernel: [10658517.223945] [<ffffffffc02dd776>]
> rpc_run_task+0xf6/0x150 [sunrpc]
> Jun 6 19:31:35 client kernel: [10658517.224029] [<ffffffffc04d28c3>]
> nfs4_call_sync_sequence+0x63/0xa0 [nfsv4]
> Jun 6 19:31:35 client kernel: [10658517.224181] [<ffffffffc04d394c>]
> _nfs4_proc_getattr+0xcc/0xf0 [nfsv4]
> Jun 6 19:31:35 client kernel: [10658517.224238] [<ffffffffc04df8f2>]
> nfs4_proc_getattr+0x72/0xf0 [nfsv4]
> Jun 6 19:31:35 client kernel: [10658517.224305] [<ffffffffc049c43f>]
> __nfs_revalidate_inode+0xbf/0x310 [nfs]
> Jun 6 19:31:35 client kernel: [10658517.224350] [<ffffffffc049ca55>]
> nfs_getattr+0x95/0x250 [nfs]
> Jun 6 19:31:35 client kernel: [10658517.224356] [<ffffffff8120872f>] ?
> cp_new_stat+0x14f/0x180
> Jun 6 19:31:35 client kernel: [10658517.224363] [<ffffffff81208106>]
> vfs_getattr+0x46/0x80
> Jun 6 19:31:35 client kernel: [10658517.224369] [<ffffffff81208235>]
> vfs_fstatat+0x75/0xc0
> Jun 6 19:31:35 client kernel: [10658517.224375] [<ffffffff8120878e>]
> SYSC_newstat+0x2e/0x60
> Jun 6 19:31:35 client kernel: [10658517.224381] [<ffffffff811212c6>] ?
> __audit_syscall_exit+0x1e6/0x280
> Jun 6 19:31:35 client kernel: [10658517.224387] [<ffffffff81208a6e>]
> SyS_newstat+0xe/0x10
> Jun 6 19:31:35 client kernel: [10658517.224393] [<ffffffff816b89fd>]
> system_call_fastpath+0x16/0x1b
>
>
> Same stack for the process 90 minutes later:
>
>
> Jun 6 20:58:01 client kernel: [10663703.685238] df D
> ffff8802173d1fa0 0 20131 19284 0x00000086
> Jun 6 20:58:01 client kernel: [10663703.685242] Call Trace:
> Jun 6 20:58:01 client kernel: [10663703.685247] [<ffffffff816ab6d9>]
> schedule+0x29/0x70
> Jun 6 20:58:01 client kernel: [10663703.685257] [<ffffffffc03367f8>]
> gss_cred_init+0x2b8/0x3f0 [auth_rpcgss]
> Jun 6 20:58:01 client kernel: [10663703.685262] [<ffffffff810b34b0>] ?
> wake_up_atomic_t+0x30/0x30
> Jun 6 20:58:01 client kernel: [10663703.685297] [<ffffffffc02eebe9>]
> rpcauth_lookup_credcache+0x219/0x2b0 [sunrpc]
> Jun 6 20:58:01 client kernel: [10663703.685391] [<ffffffffc0334623>]
> gss_lookup_cred+0x13/0x20 [auth_rpcgss]
> Jun 6 20:58:01 client kernel: [10663703.685560] [<ffffffffc02ee2db>]
> rpcauth_lookupcred+0x8b/0xd0 [sunrpc]
> Jun 6 20:58:01 client kernel: [10663703.685597] [<ffffffffc02ef0dd>]
> rpcauth_refreshcred+0x14d/0x1d0 [sunrpc]
> Jun 6 20:58:01 client kernel: [10663703.685836] [<ffffffffc02e299a>] ?
> xprt_lock_and_alloc_slot+0x6a/0x80 [sunrpc]
> Jun 6 20:58:01 client kernel: [10663703.685888] [<ffffffffc02dddf0>] ?
> call_bc_transmit+0x1b0/0x1b0 [sunrpc]
> Jun 6 20:58:01 client kernel: [10663703.685997] [<ffffffffc02dddf0>] ?
> call_bc_transmit+0x1b0/0x1b0 [sunrpc]
> Jun 6 20:58:01 client kernel: [10663703.686179] [<ffffffffc02de320>] ?
> call_retry_reserve+0x60/0x60 [sunrpc]
> Jun 6 20:58:01 client kernel: [10663703.686227] [<ffffffffc02de320>] ?
> call_retry_reserve+0x60/0x60 [sunrpc]
> Jun 6 20:58:01 client kernel: [10663703.686415] [<ffffffffc02de35c>]
> call_refresh+0x3c/0x60 [sunrpc]
> Jun 6 20:58:01 client kernel: [10663703.686514] [<ffffffffc02ec017>]
> __rpc_execute+0x97/0x410 [sunrpc]
> Jun 6 20:58:01 client kernel: [10663703.686519] [<ffffffff810b3475>] ?
> wake_up_bit+0x25/0x30
> Jun 6 20:58:01 client kernel: [10663703.686556] [<ffffffffc02ed7b8>]
> rpc_execute+0x68/0xb0 [sunrpc]
> Jun 6 20:58:01 client kernel: [10663703.686712] [<ffffffffc02dd776>]
> rpc_run_task+0xf6/0x150 [sunrpc]
> Jun 6 20:58:01 client kernel: [10663703.686852] [<ffffffffc04d28c3>]
> nfs4_call_sync_sequence+0x63/0xa0 [nfsv4]
> Jun 6 20:58:01 client kernel: [10663703.686887] [<ffffffffc04d394c>]
> _nfs4_proc_getattr+0xcc/0xf0 [nfsv4]
> Jun 6 20:58:01 client kernel: [10663703.687127] [<ffffffffc04df8f2>]
> nfs4_proc_getattr+0x72/0xf0 [nfsv4]
> Jun 6 20:58:01 client kernel: [10663703.687153] [<ffffffffc049c43f>]
> __nfs_revalidate_inode+0xbf/0x310 [nfs]
> Jun 6 20:58:01 client kernel: [10663703.687403] [<ffffffffc049ca55>]
> nfs_getattr+0x95/0x250 [nfs]
> Jun 6 20:58:01 client kernel: [10663703.687409] [<ffffffff8120872f>] ?
> cp_new_stat+0x14f/0x180
> Jun 6 20:58:01 client kernel: [10663703.687414] [<ffffffff81208106>]
> vfs_getattr+0x46/0x80
> Jun 6 20:58:01 client kernel: [10663703.687419] [<ffffffff81208235>]
> vfs_fstatat+0x75/0xc0
> Jun 6 20:58:01 client kernel: [10663703.687425] [<ffffffff8120878e>]
> SYSC_newstat+0x2e/0x60
> Jun 6 20:58:01 client kernel: [10663703.687430] [<ffffffff811212c6>] ?
> __audit_syscall_exit+0x1e6/0x280
> Jun 6 20:58:01 client kernel: [10663703.687436] [<ffffffff81208a6e>]
> SyS_newstat+0xe/0x10
> Jun 6 20:58:01 client kernel: [10663703.687440] [<ffffffff816b89fd>]
> system_call_fastpath+0x16/0x1b
>
>
>
>
>
> The client doesn't call nfs4_recovery_handle_error():
>
>
> [root@client root]# stap -e 'probe
> module("nfsv4").function("nfs4_recovery_handle_error"){print_backtrace()}'
>
> I waited a couple of minutes - no output.
> Which is strange...
>
>
> The affected nfs server is BADnfssrv1 [10.100.139.63]
>
>
> [root@client root]# stap -e 'probe
> module("nfsv4").function("nfs4_renew_state") \
> { printf("%s %s least_time: %d secs_to_renew:
> %d server: %s\n", ctime(gettimeofday_s()), probefunc(),
> $clp->cl_lease_time/HZ(), (jiffies()-$clp->cl_last_renewal)/HZ(),
> kernel_string($clp->cl_hostname)) }'
>
>
> Sat Jun 6 14:03:07 2020 nfs4_renew_state least_time: 30 secs_to_renew: 20
> server: nfsserv1.company.domain
> Sat Jun 6 14:03:10 2020 nfs4_renew_state least_time: 30 secs_to_renew: 5826
> server: BADnfssrv1.company.domain
> Sat Jun 6 14:03:14 2020 nfs4_renew_state least_time: 30 secs_to_renew: 20
> server: nfsserv2.company.domain
> Sat Jun 6 14:03:15 2020 nfs4_renew_state least_time: 30 secs_to_renew: 5831
> server: BADnfssrv1.company.domain
> Sat Jun 6 14:03:20 2020 nfs4_renew_state least_time: 30 secs_to_renew: 20
> server: lovpesgfs1.company.domain
> Sat Jun 6 14:03:20 2020 nfs4_renew_state least_time: 30 secs_to_renew: 5836
> server: BADnfssrv1.company.domain
> Sat Jun 6 14:03:25 2020 nfs4_renew_state least_time: 30 secs_to_renew: 5841
> server: BADnfssrv1.company.domain
> Sat Jun 6 14:03:27 2020 nfs4_renew_state least_time: 30 secs_to_renew: 20
> server: nfsserv1.company.domain
> Sat Jun 6 14:03:31 2020 nfs4_renew_state least_time: 30 secs_to_renew: 5847
> server: BADnfssrv1.company.domain
> Sat Jun 6 14:03:34 2020 nfs4_renew_state least_time: 30 secs_to_renew: 20
> server: nfsserv2.company.domain
> Sat Jun 6 14:03:36 2020 nfs4_renew_state least_time: 30 secs_to_renew: 5852
> server: BADnfssrv1.company.domain
> ...
>
>
> Notice that the last time BADnfssrv1 renewed its lease was over 90 minutes
> ago. Other nfs servers are fine.
> The NetApp ONTAP upgrade (clustered) was executed about 90 minutes ago.
>
>
> [root@client root]# stap -e 'probe
> module("nfsv4").function("nfs4_proc_async_renew") \
> { printf("%s %s %d\n", ctime(gettimeofday_s()),
> kernel_string($clp->cl_hostname), $renew_flags) }'
> Sat Jun 6 14:13:05 2020 BADnfssrv1.company.domain 1
> Sat Jun 6 14:13:08 2020 nfsserv1.company.domain 1
> Sat Jun 6 14:13:11 2020 BADnfssrv1.company.domain 1
> ...
>
>
> The function nfs4_renew_done() in linux-3.10.0-693.11.6.el7 is:
>
> static void nfs4_renew_done(struct rpc_task *task, void *calldata)
> {
> struct nfs4_renewdata *data = calldata;
> struct nfs_client *clp = data->client;
> unsigned long timestamp = data->timestamp;
>
> trace_nfs4_renew_async(clp, task->tk_status);
> switch (task->tk_status) {
> case 0:
> break;
> case -NFS4ERR_LEASE_MOVED:
> nfs4_schedule_lease_moved_recovery(clp);
> break;
> default:
> /* Unless we're shutting down, schedule state recovery! */
> if (test_bit(NFS_CS_RENEWD, &clp->cl_res_state) == 0)
> return;
> if (task->tk_status != NFS4ERR_CB_PATH_DOWN) {
> nfs4_schedule_lease_recovery(clp);
> return;
> }
> nfs4_schedule_path_down_recovery(clp);
> }
> do_renew_lease(clp, timestamp);
> }
>
>
>
> [root@client root]# stap -e 'probe
> module("nfsv4").function("nfs4_renew_done") \
> { clp=$data->client; printf("%s %s tk_status:
> %d\n", ctime(gettimeofday_s()), kernel_string(clp->cl_hostname),
> $task->tk_status) } \
> probe
> module("nfsv4").function("nfs4_schedule_lease_recovery") \
> { printf("%s nfs4_schedule_lease_recovery(): %s
> cl_state: %d\n", ctime(gettimeofday_s()), kernel_string($clp->cl_hostname),
> $clp->cl_state) } \
> probe
> module("nfsv4").function("do_renew_lease")\
> { printf("%s do_renew_lease(): %s\n",
> ctime(gettimeofday_s()), kernel_string($clp->cl_hostname)) }'
>
> Sat Jun 6 14:42:06 2020 BADnfssrv1.company.domain tk_status: -10022
> Sat Jun 6 14:42:06 2020 nfs4_schedule_lease_recovery():
> BADnfssrv1.company.domain cl_state: 5
> Sat Jun 6 14:42:11 2020 nfsserv1.company.domain tk_status: 0
> Sat Jun 6 14:42:11 2020 do_renew_lease(): nfsserv1.company.domain
> Sat Jun 6 14:42:11 2020 BADnfssrv1.company.domain tk_status: -10022
> Sat Jun 6 14:42:11 2020 nfs4_schedule_lease_recovery():
> BADnfssrv1.company.domain cl_state: 5
> Sat Jun 6 14:42:16 2020 BADnfssrv1.company.domain tk_status: -10022
> Sat Jun 6 14:42:16 2020 nfs4_schedule_lease_recovery():
> BADnfssrv1.company.domain cl_state: 5
> Sat Jun 6 14:42:18 2020 nfsserv2.company.domain tk_status: 0
> Sat Jun 6 14:42:18 2020 do_renew_lease(): nfsserv2.company.domain
> Sat Jun 6 14:42:21 2020 BADnfssrv1.company.domain tk_status: -10022
> Sat Jun 6 14:42:21 2020 nfs4_schedule_lease_recovery():
> BADnfssrv1.company.domain cl_state: 5
> ^C
>
>
> The -10022 is NFS4ERR_STALE_CLIENTID as seen in network dump.
>
>
> The nfs4_schedule_lease_recovery() calls nfs4_schedule_state_manager():
>
>
> void nfs4_schedule_state_manager(struct nfs_client *clp)
> {
> struct task_struct *task;
> char buf[INET6_ADDRSTRLEN + sizeof("-manager") + 1];
>
> if (test_and_set_bit(NFS4CLNT_MANAGER_RUNNING, &clp->cl_state) != 0)
> return;
> ...
>
>
> Where NFS4CLNT_MANAGER_RUNNING is bit 0, so given cl_state == 5 the bit is
> set.
> Let's get stack for the 10.200.0.10-man(ager) kthread:
>
>
> [root@client root]# echo t >/proc/sysrq-trigger
> [root@client root]# less /var/log/messages
> ...
> Jun 6 19:31:35 client kernel: [10658517.225231] 10.200.0.10-man S
> ffff880229e7af70 0 5424 2 0x00000080
> Jun 6 19:31:35 client kernel: [10658517.225236] Call Trace:
> Jun 6 19:31:35 client kernel: [10658517.225277] [<ffffffffc02dffb0>] ?
> rpc_release_client+0x90/0xb0 [sunrpc]
> Jun 6 19:31:35 client kernel: [10658517.225309] [<ffffffff816ab6d9>]
> schedule+0x29/0x70
> Jun 6 19:31:35 client kernel: [10658517.225355] [<ffffffff816a90e9>]
> schedule_timeout+0x239/0x2c0
> Jun 6 19:31:35 client kernel: [10658517.225386] [<ffffffff811e0922>] ?
> kmem_cache_free+0x1e2/0x200
> Jun 6 19:31:35 client kernel: [10658517.225437] [<ffffffff81187177>] ?
> mempool_free_slab+0x17/0x20
> Jun 6 19:31:35 client kernel: [10658517.225469] [<ffffffff81187579>] ?
> mempool_free+0x49/0x90
> Jun 6 19:31:35 client kernel: [10658517.225513] [<ffffffff816ac441>]
> wait_for_completion_interruptible+0x131/0x1a0
> Jun 6 19:31:35 client kernel: [10658517.225543] [<ffffffff810c6440>] ?
> wake_up_state+0x20/0x20
> Jun 6 19:31:35 client kernel: [10658517.225590] [<ffffffffc04f0a70>]
> nfs4_drain_slot_tbl+0x60/0x70 [nfsv4]
> Jun 6 19:31:35 client kernel: [10658517.225650] [<ffffffffc04f0a97>]
> nfs4_begin_drain_session.isra.11+0x17/0x40 [nfsv4]
> Jun 6 19:31:35 client kernel: [10658517.225685] [<ffffffffc04f137f>]
> nfs4_establish_lease+0x2f/0x80 [nfsv4]
> Jun 6 19:31:35 client kernel: [10658517.225727] [<ffffffffc04f2818>]
> nfs4_state_manager+0x1d8/0x8c0 [nfsv4]
> Jun 6 19:31:35 client kernel: [10658517.225764] [<ffffffffc04f2f00>] ?
> nfs4_state_manager+0x8c0/0x8c0 [nfsv4]
> Jun 6 19:31:35 client kernel: [10658517.225854] [<ffffffffc04f2f1f>]
> nfs4_run_state_manager+0x1f/0x40 [nfsv4]
> Jun 6 19:31:35 client kernel: [10658517.225912] [<ffffffff810b252f>]
> kthread+0xcf/0xe0
> Jun 6 19:31:35 client kernel: [10658517.225976] [<ffffffff810b2460>] ?
> insert_kthread_work+0x40/0x40
> Jun 6 19:31:35 client kernel: [10658517.226000] [<ffffffff816b8798>]
> ret_from_fork+0x58/0x90
> Jun 6 19:31:35 client kernel: [10658517.226045] [<ffffffff810b2460>] ?
> insert_kthread_work+0x40/0x40
>
> ...
>
>
> I sent the sysrq/t couple of minutes later and then again later and each
> time I get exactly same stack as above for the same pid (5424).
> Notice that the kthread name is server IP-man(ager) and the IP address
> matches the IP of the nfs server we are having issue with on this client.
>
>
> So if I'm reading it correctly what is happening is that client sends RENEW
> op, gets NFS4ERR_STALE_CLIENTID (-10022),
> schedules lease recovery which sets NFS4CLNT_CHECK_LEASE (in
> nfs4_schedule_lease_recovery() and tries to run
> nfs4_schedule_state_manager(),
> which ends up not doing anything as the kthread is already running and
> should deal with the NFS4CLNT_CHECK_LEASE bit set. However as the
> nfs4_state_manager() is stuck
> on draining slot it never processes the NFS4CLNT_CHECK_LEASE. This explains
> why network dump is showing the client looping on RENEW ops being send,
> getting the error and not recovering (not setting new client id, etc.). It
> also explains why other processes issuing any i/o to a file system served by
> the server are stuck.
>
>
> Given the stack, it is stuck here on wait_for_completion_interruptible()
> (also notice the rpc_release_client() at the top of the stack).
>
>
> static int nfs4_drain_slot_tbl(struct nfs4_slot_table *tbl)
> {
> set_bit(NFS4_SLOT_TBL_DRAINING, &tbl->slot_tbl_state);
> spin_lock(&tbl->slot_tbl_lock);
> if (tbl->highest_used_slotid != NFS4_NO_SLOT) {
> INIT_COMPLETION(tbl->complete);
> spin_unlock(&tbl->slot_tbl_lock);
> return wait_for_completion_interruptible(&tbl->complete);
> }
> spin_unlock(&tbl->slot_tbl_lock);
> return 0;
> }
>
>
>
> I run: kill -9 5424, which fixed the issue immediately.
> (as
>
> [root@client root]# tshark -Y nfs host BADnfssrv1
> Running as user "root" and group "root". This could be dangerous.
> Capturing on 'eth0'
> 2 19.842157633 10.100.139.63 -> 10.200.0.10 NFS 230 V4 Call RENEW CID:
> 0x6428
> 3 19.916744562 10.200.0.10 -> 10.100.139.63 NFS 182 V4 Reply (Call In 2)
> RENEW
> 6 39.874158462 10.100.139.63 -> 10.200.0.10 NFS 230 V4 Call RENEW CID:
> 0x6428
> 7 39.948760040 10.200.0.10 -> 10.100.139.63 NFS 182 V4 Reply (Call In 6)
> RENEW
> 10 59.906166646 10.100.139.63 -> 10.200.0.10 NFS 230 V4 Call RENEW CID:
> 0x6428
> 11 59.980762920 10.200.0.10 -> 10.100.139.63 NFS 182 V4 Reply (Call In 10)
> RENEW
> ...
>
>
> All stuck df processes, etc. resumed as well and new i/o is working fine
> against the file server.
>
> I wasn't sure if it didn't left something in undefined state though so
> scheduled the client reboot just in case, although it seemed to be working
> fine.
>
>
>
> There is another PID 26378 which I noticed in sysrq/t output, which might be
> the culprit here:
>
> Jun 6 19:31:35 client kernel: [10658517.214810] nfsv4.0-svc S
> ffff880234b96eb0 0 26378 2 0x00000080
> Jun 6 19:31:35 client kernel: [10658517.214814] Call Trace:
> Jun 6 19:31:35 client kernel: [10658517.214820] [<ffffffff8156afaf>] ?
> sock_destroy_inode+0x2f/0x40
> Jun 6 19:31:35 client kernel: [10658517.214825] [<ffffffff8121f5a8>] ?
> destroy_inode+0x38/0x60
> Jun 6 19:31:35 client kernel: [10658517.214830] [<ffffffff816ab6d9>]
> schedule+0x29/0x70
> Jun 6 19:31:35 client kernel: [10658517.214835] [<ffffffff816a90e9>]
> schedule_timeout+0x239/0x2c0
> Jun 6 19:31:35 client kernel: [10658517.214880] [<ffffffffc02ffd61>] ?
> svc_xprt_free+0x71/0x90 [sunrpc]
> Jun 6 19:31:35 client kernel: [10658517.214915] [<ffffffffc03018d1>]
> svc_recv+0x971/0xb60 [sunrpc]
> Jun 6 19:31:35 client kernel: [10658517.214950] [<ffffffffc04f7d40>] ?
> nfs_callback_authenticate+0x60/0x60 [nfsv4]
> Jun 6 19:31:35 client kernel: [10658517.214984] [<ffffffffc04f7d40>] ?
> nfs_callback_authenticate+0x60/0x60 [nfsv4]
> Jun 6 19:31:35 client kernel: [10658517.215019] [<ffffffffc04f7d73>]
> nfs4_callback_svc+0x33/0x60 [nfsv4]
> Jun 6 19:31:35 client kernel: [10658517.215024] [<ffffffff810b252f>]
> kthread+0xcf/0xe0
> Jun 6 19:31:35 client kernel: [10658517.215030] [<ffffffff810b2460>] ?
> insert_kthread_work+0x40/0x40
> Jun 6 19:31:35 client kernel: [10658517.215035] [<ffffffff816b8798>]
> ret_from_fork+0x58/0x90
> Jun 6 19:31:35 client kernel: [10658517.215041] [<ffffffff810b2460>] ?
> insert_kthread_work+0x40/0x40
>
>
> It is showing up, with the same stack, in every sysrq/t output collected,
> even almost 90 minutes later:
>
> Jun 6 20:58:01 client kernel: [10663703.676521] nfsv4.0-svc S
> ffff880234b96eb0 0 26378 2 0x00000080
> Jun 6 20:58:01 client kernel: [10663703.676525] Call Trace:
> Jun 6 20:58:01 client kernel: [10663703.676531] [<ffffffff8156afaf>] ?
> sock_destroy_inode+0x2f/0x40
> Jun 6 20:58:01 client kernel: [10663703.676536] [<ffffffff8121f5a8>] ?
> destroy_inode+0x38/0x60
> Jun 6 20:58:01 client kernel: [10663703.676541] [<ffffffff816ab6d9>]
> schedule+0x29/0x70
> Jun 6 20:58:01 client kernel: [10663703.676545] [<ffffffff816a90e9>]
> schedule_timeout+0x239/0x2c0
> Jun 6 20:58:01 client kernel: [10663703.676550] [<ffffffff811e0e03>] ?
> kfree+0x103/0x140
> Jun 6 20:58:01 client kernel: [10663703.676595] [<ffffffffc02ffd61>] ?
> svc_xprt_free+0x71/0x90 [sunrpc]
> Jun 6 20:58:01 client kernel: [10663703.676633] [<ffffffffc03018d1>]
> svc_recv+0x971/0xb60 [sunrpc]
> Jun 6 20:58:01 client kernel: [10663703.676676] [<ffffffffc04f7d40>] ?
> nfs_callback_authenticate+0x60/0x60 [nfsv4]
> Jun 6 20:58:01 client kernel: [10663703.676709] [<ffffffffc04f7d40>] ?
> nfs_callback_authenticate+0x60/0x60 [nfsv4]
> Jun 6 20:58:01 client kernel: [10663703.676745] [<ffffffffc04f7d73>]
> nfs4_callback_svc+0x33/0x60 [nfsv4]
> Jun 6 20:58:01 client kernel: [10663703.676750] [<ffffffff810b252f>]
> kthread+0xcf/0xe0
> Jun 6 20:58:01 client kernel: [10663703.676756] [<ffffffff810b2460>] ?
> insert_kthread_work+0x40/0x40
> Jun 6 20:58:01 client kernel: [10663703.676761] [<ffffffff816b8798>]
> ret_from_fork+0x58/0x90
> Jun 6 20:58:01 client kernel: [10663703.676766] [<ffffffff810b2460>] ?
> insert_kthread_work+0x40/0x40
>
>
>
>
> Looks like it is a deadlock which depends on timing during nfs server
> failovers.
>
> Hopefully the above will be useful for someone more familiar with the actual
> implementation.
> I'm happy to try to debug it more next time it happens - open to any ideas
> what to look for.
>
>
> I briefly went thru git changelog and maybe on of the below fixes might be
> addressing the issue.
>
>
> commit 6221f1d9b63fed6260273e59a2b89ab30537a811
> Author: Chuck Lever <chuck.lever@xxxxxxxxxx>
> Date: Fri Apr 17 12:40:31 2020 -0400
>
> SUNRPC: Fix backchannel RPC soft lockups
> ...
>
> commit 67e7b52d44e3d539dfbfcd866c3d3d69da23a909
> Author: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
> Date: Wed Aug 7 07:31:27 2019 -0400
>
> NFSv4: Ensure state recovery handles ETIMEDOUT correctly
>
> ...
>
> commit 76ee03540f316948c3bc89fc76ded86c88e887a5
> Author: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx>
> Date: Tue Jan 10 16:49:31 2017 -0500
>
> NFS: Check if the slot table is draining from nfs4_setup_sequence()
> ...
>
>
> commit 6994cdd798568a0ddb8e0a85e2af24dbe655c341
> Author: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx>
> Date: Tue Jan 10 16:13:27 2017 -0500
>
> NFS: Lock the slot table from a single place during setup sequence
>
> Rather than implementing this twice for NFS v4.0 and v4.1
> ...
>
>
>
>
> --
> Robert Milkowski
>
>
>
--
Chuck Lever
