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Message-ID: <44c2101e756f7c3b876fb9c58da3ebd089dc14d5.camel@kernel.org>
Subject: Re: nfsd hangs and nfsd_break_deleg_cb+0x170/0x190 warning
From: Jeff Layton <jlayton@kernel.org>
To: Rik Theys <Rik.Theys@esat.kuleuven.be>, Linux Nfs
	 <linux-nfs@vger.kernel.org>
Date: Tue, 12 Mar 2024 08:47:08 -0400
In-Reply-To: <66c98f4c-5e52-4fa3-8a2c-9379cfec2a9a@esat.kuleuven.be>
References: <66c98f4c-5e52-4fa3-8a2c-9379cfec2a9a@esat.kuleuven.be>
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On Tue, 2024-03-12 at 13:24 +0100, Rik Theys wrote:
> Hi Jeff,
>=20
> On 3/12/24 12:22, Jeff Layton wrote:
> > On Mon, 2024-03-11 at 19:43 +0100, Rik Theys wrote:
> > > Since a few weeks our Rocky Linux 9 NFS server has periodically logge=
d hung nfsd tasks. The initial effect was that some clients could no longer=
 access the NFS server. This got worse and worse (probably as more nfsd thr=
eads got blocked) and we had to restart the server. Restarting the server a=
lso failed as the NFS server service could no longer be stopped.
> > >  =20
> > >=20
> > > The initial kernel we noticed this behavior on was kernel-5.14.0-362.=
18.1.el9_3.x86_64. Since then we've installed kernel-5.14.0-419.el9.x86_64 =
from CentOS Stream 9. The same issue happened again on this newer kernel ve=
rsion:
> > >  =20

419 is fairly up to date with nfsd changes. There are some known bugs
around callbacks, and there is a draft MR in flight to fix it.

What kernel were you on prior to 5.14.0-362.18.1.el9_3.x86_64 ? If we
can bracket the changes around a particular version, then that might
help identify the problem.

> > > [Mon Mar 11 14:10:08 2024] =A0=A0=A0=A0=A0=A0Not tainted 5.14.0-419.e=
l9.x86_64 #1
> > >  =A0[Mon Mar 11 14:10:08 2024] "echo 0 > /proc/sys/kernel/hung_task_t=
imeout_secs" disables this message.
> > >  =A0[Mon Mar 11 14:10:08 2024] task:nfsd =A0=A0=A0=A0=A0=A0=A0=A0=A0=
=A0=A0state:D stack:0 =A0=A0=A0=A0pid:8865 =A0ppid:2 =A0=A0=A0=A0=A0flags:0=
x00004000
> > >  =A0[Mon Mar 11 14:10:08 2024] Call Trace:
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0<TASK>
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0__schedule+0x21b/0x550
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0schedule+0x2d/0x70
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0schedule_timeout+0x11f/0x160
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0? select_idle_sibling+0x28/0x430
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0? wake_affine+0x62/0x1f0
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0__wait_for_common+0x90/0x1d0
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0? __pfx_schedule_timeout+0x10/0x10
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0__flush_workqueue+0x13a/0x3f0
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0nfsd4_shutdown_callback+0x49/0x120 =
[nfsd]
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0? nfsd4_cld_remove+0x54/0x1d0 [nfsd=
]
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0? nfsd4_return_all_client_layouts+0=
xc4/0xf0 [nfsd]
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0? nfsd4_shutdown_copy+0x68/0xc0 [nf=
sd]
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0__destroy_client+0x1f3/0x290 [nfsd]
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0nfsd4_exchange_id+0x75f/0x770 [nfsd=
]
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0? nfsd4_decode_opaque+0x3a/0x90 [nf=
sd]
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0nfsd4_proc_compound+0x44b/0x700 [nf=
sd]
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0nfsd_dispatch+0x94/0x1c0 [nfsd]
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0svc_process_common+0x2ec/0x660 [sun=
rpc]
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0? __pfx_nfsd_dispatch+0x10/0x10 [nf=
sd]
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0? __pfx_nfsd+0x10/0x10 [nfsd]
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0svc_process+0x12d/0x170 [sunrpc]
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0nfsd+0x84/0xb0 [nfsd]
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0kthread+0xdd/0x100
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0? __pfx_kthread+0x10/0x10
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0ret_from_fork+0x29/0x50
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0</TASK>
> > >  =A0[Mon Mar 11 14:10:08 2024] INFO: task nfsd:8866 blocked for more =
than 122 seconds.
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0=A0=A0=A0=A0=A0Not tainted 5.14.0-4=
19.el9.x86_64 #1
> > >  =A0[Mon Mar 11 14:10:08 2024] "echo 0 > /proc/sys/kernel/hung_task_t=
imeout_secs" disables this message.
> > >  =A0[Mon Mar 11 14:10:08 2024] task:nfsd =A0=A0=A0=A0=A0=A0=A0=A0=A0=
=A0=A0state:D stack:0 =A0=A0=A0=A0pid:8866 =A0ppid:2 =A0=A0=A0=A0=A0flags:0=
x00004000
> > >  =A0[Mon Mar 11 14:10:08 2024] Call Trace:
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0<TASK>
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0__schedule+0x21b/0x550
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0schedule+0x2d/0x70
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0schedule_timeout+0x11f/0x160
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0? select_idle_sibling+0x28/0x430
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0? tcp_recvmsg+0x196/0x210
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0? wake_affine+0x62/0x1f0
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0__wait_for_common+0x90/0x1d0
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0? __pfx_schedule_timeout+0x10/0x10
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0__flush_workqueue+0x13a/0x3f0
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0nfsd4_destroy_session+0x1a4/0x240 [=
nfsd]
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0nfsd4_proc_compound+0x44b/0x700 [nf=
sd]
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0nfsd_dispatch+0x94/0x1c0 [nfsd]
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0svc_process_common+0x2ec/0x660 [sun=
rpc]
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0? __pfx_nfsd_dispatch+0x10/0x10 [nf=
sd]
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0? __pfx_nfsd+0x10/0x10 [nfsd]
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0svc_process+0x12d/0x170 [sunrpc]
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0nfsd+0x84/0xb0 [nfsd]
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0kthread+0xdd/0x100
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0? __pfx_kthread+0x10/0x10
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0ret_from_fork+0x29/0x50
> > >  =A0[Mon Mar 11 14:10:08 2024] =A0</TASK>
> > >=20
> > The above threads are trying to flush the workqueue, so that probably
> > means that they are stuck waiting on a workqueue job to finish.
> > >  =A0The above is repeated a few times, and then this warning is also =
logged:
> > >  =20
> > > [Mon Mar 11 14:12:04 2024] ------------[ cut here ]------------
> > >  =A0[Mon Mar 11 14:12:04 2024] WARNING: CPU: 39 PID: 8844 at fs/nfsd/=
nfs4state.c:4919 nfsd_break_deleg_cb+0x170/0x190 [nfsd]
> > >  =A0[Mon Mar 11 14:12:05 2024] Modules linked in: nfsv4 dns_resolver =
nfs fscache netfs rpcsec_gss_krb5 rpcrdma rdma_cm iw_cm ib_cm ib_core binfm=
t_misc bonding tls rfkill nft_counter nft_ct
> > >  =A0nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nft_reject_inet nf_rej=
ect_ipv4 nf_reject_ipv6 nft_reject nf_tables nfnetlink vfat fat dm_thin_poo=
l dm_persistent_data dm_bio_prison dm_bufio l
> > >  =A0ibcrc32c dm_service_time dm_multipath intel_rapl_msr intel_rapl_c=
ommon intel_uncore_frequency intel_uncore_frequency_common isst_if_common s=
kx_edac nfit libnvdimm ipmi_ssif x86_pkg_temp
> > >  =A0_thermal intel_powerclamp coretemp kvm_intel kvm irqbypass dcdbas=
 rapl intel_cstate mgag200 i2c_algo_bit drm_shmem_helper dell_smbios drm_km=
s_helper dell_wmi_descriptor wmi_bmof intel_u
> > >  =A0ncore syscopyarea pcspkr sysfillrect mei_me sysimgblt acpi_ipmi m=
ei fb_sys_fops i2c_i801 ipmi_si intel_pch_thermal lpc_ich ipmi_devintf i2c_=
smbus ipmi_msghandler joydev acpi_power_meter
> > >  =A0nfsd auth_rpcgss nfs_acl drm lockd grace fuse sunrpc ext4 mbcache=
 jbd2 sd_mod sg lpfc
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0nvmet_fc nvmet nvme_fc nvme_fabrics=
 crct10dif_pclmul ahci libahci crc32_pclmul nvme_core crc32c_intel ixgbe me=
garaid_sas libata nvme_common ghash_clmulni_int
> > >  =A0el t10_pi wdat_wdt scsi_transport_fc mdio wmi dca dm_mirror dm_re=
gion_hash dm_log dm_mod
> > >  =A0[Mon Mar 11 14:12:05 2024] CPU: 39 PID: 8844 Comm: nfsd Not taint=
ed 5.14.0-419.el9.x86_64 #1
> > >  =A0[Mon Mar 11 14:12:05 2024] Hardware name: Dell Inc. PowerEdge R74=
0/00WGD1, BIOS 2.20.1 09/13/2023
> > >  =A0[Mon Mar 11 14:12:05 2024] RIP: 0010:nfsd_break_deleg_cb+0x170/0x=
190 [nfsd]
> > >  =A0[Mon Mar 11 14:12:05 2024] Code: a6 95 c5 f3 e9 ff fe ff ff 48 89=
 df be 01 00 00 00 e8 34 b5 13 f4 48 8d bb 98 00 00 00 e8 c8 f9 00 00 84 c0=
 0f 85 2e ff ff ff <0f> 0b e9 27 ff ff ff be
> > >  =A002 00 00 00 48 89 df e8 0c b5 13 f4 e9 01
> > >  =A0[Mon Mar 11 14:12:05 2024] RSP: 0018:ffff9929e0bb7b80 EFLAGS: 000=
10246
> > >  =A0[Mon Mar 11 14:12:05 2024] RAX: 0000000000000000 RBX: ffff8ada519=
30900 RCX: 0000000000000024
> > >  =A0[Mon Mar 11 14:12:05 2024] RDX: ffff8ada519309c8 RSI: ffff8ad5829=
33c00 RDI: 0000000000002000
> > >  =A0[Mon Mar 11 14:12:05 2024] RBP: ffff8ad46bf21574 R08: ffff9929e0b=
b7b48 R09: 0000000000000000
> > >  =A0[Mon Mar 11 14:12:05 2024] R10: ffff8aec859a2948 R11: 00000000000=
00000 R12: ffff8ad6f497c360
> > >  =A0[Mon Mar 11 14:12:05 2024] R13: ffff8ad46bf21560 R14: ffff8ae5942=
e0b10 R15: ffff8ad6f497c360
> > >  =A0[Mon Mar 11 14:12:05 2024] FS: =A00000000000000000(0000) GS:ffff8=
b031fcc0000(0000) knlGS:0000000000000000
> > >  =A0[Mon Mar 11 14:12:05 2024] CS: =A00010 DS: 0000 ES: 0000 CR0: 000=
0000080050033
> > >  =A0[Mon Mar 11 14:12:05 2024] CR2: 00007fafe2060744 CR3: 00000018e58=
de006 CR4: 00000000007706e0
> > >  =A0[Mon Mar 11 14:12:05 2024] DR0: 0000000000000000 DR1: 00000000000=
00000 DR2: 0000000000000000
> > >  =A0[Mon Mar 11 14:12:05 2024] DR3: 0000000000000000 DR6: 00000000fff=
e0ff0 DR7: 0000000000000400
> > >  =A0[Mon Mar 11 14:12:05 2024] PKRU: 55555554
> > >  =A0[Mon Mar 11 14:12:05 2024] Call Trace:
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0<TASK>
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0? show_trace_log_lvl+0x1c4/0x2df
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0? show_trace_log_lvl+0x1c4/0x2df
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0? __break_lease+0x16f/0x5f0
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0? nfsd_break_deleg_cb+0x170/0x190 [=
nfsd]
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0? __warn+0x81/0x110
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0? nfsd_break_deleg_cb+0x170/0x190 [=
nfsd]
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0? report_bug+0x10a/0x140
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0? handle_bug+0x3c/0x70
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0? exc_invalid_op+0x14/0x70
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0? asm_exc_invalid_op+0x16/0x20
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0? nfsd_break_deleg_cb+0x170/0x190 [=
nfsd]
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0__break_lease+0x16f/0x5f0
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0? nfsd_file_lookup_locked+0x117/0x1=
60 [nfsd]
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0? list_lru_del+0x101/0x150
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0nfsd_file_do_acquire+0x790/0x830 [n=
fsd]
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0nfs4_get_vfs_file+0x315/0x3a0 [nfsd=
]
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0nfsd4_process_open2+0x430/0xa30 [nf=
sd]
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0? fh_verify+0x297/0x2f0 [nfsd]
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0nfsd4_open+0x3ce/0x4b0 [nfsd]
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0nfsd4_proc_compound+0x44b/0x700 [nf=
sd]
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0nfsd_dispatch+0x94/0x1c0 [nfsd]
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0svc_process_common+0x2ec/0x660 [sun=
rpc]
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0? __pfx_nfsd_dispatch+0x10/0x10 [nf=
sd]
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0? __pfx_nfsd+0x10/0x10 [nfsd]
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0svc_process+0x12d/0x170 [sunrpc]
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0nfsd+0x84/0xb0 [nfsd]
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0kthread+0xdd/0x100
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0? __pfx_kthread+0x10/0x10
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0ret_from_fork+0x29/0x50
> > >  =A0[Mon Mar 11 14:12:05 2024] =A0</TASK>
> > >  =A0[Mon Mar 11 14:12:05 2024] ---[ end trace 7a039e17443dc651 ]---
> > This is probably this WARN in nfsd_break_one_deleg:
> >=20
> >          WARN_ON_ONCE(!nfsd4_run_cb(&dp->dl_recall));
> >=20
> > It means that a delegation break callback to the client couldn't be
> > queued to the workqueue, and so it didn't run.
> >=20
> > > Could this be the same issue as described here:https://lore.kernel.or=
g/linux-nfs/af0ec881-5ebf-4feb-98ae-3ed2a77f86f1@oracle.com/ ?
> > >  =20
> > Yes, most likely the same problem.
> If I read that thread correctly, this issue was introduced between=20
> 6.1.63 and 6.6.3? Is it possible the EL9 5.14.0-362.18.1.el9_3=20
> backported these changes, or were we hitting some other bug with that=20
> version? It seems the 6.1.x kernel is not affected? If so, that would be=
=20
> the recommended kernel to run?

Anything is possible. We have to identify the problem first.
>=20


> >=20
> > > As described in that thread, I've tried to obtain the requested infor=
mation.
> > >  =20
> > >=20
> > > Is it possible this is the issue that was fixed by the patches descri=
bed here? https://lore.kernel.org/linux-nfs/2024022054-cause-suffering-eae8=
@gregkh/
> > >=20
> > Doubtful. Those are targeted toward a different set of issues.
> >=20
> > If you're willing, I do have some patches queued up for CentOS here tha=
t
> > fix some backchannel problems that could be related. I'm mainly waiting
> > on Chuck to send these to Linus and then we'll likely merge them into
> > CentOS soon afterward:
> >=20
> > https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/me=
rge_requests/3689
> >=20
> If you can send me a patch file, I can rebuild the C9S kernel with that=
=20
> patch and run it. It can take a while for the bug to trigger as I=20
> believe it seems to be very workload dependent (we were running very=20
> stable for months and now hit this bug every other week).
>=20
>=20

It's probably simpler to just pull down the build artifacts for that MR.
You have to drill down through the CI for it, but they are here:

https://s3.amazonaws.com/arr-cki-prod-trusted-artifacts/index.html?prefix=
=3Dtrusted-artifacts/1194300175/publish_x86_64/6278921877/artifacts/

There's even a repo file you can install on the box to pull them down.
--=20
Jeff Layton <jlayton@kernel.org>