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From: Christian Theune <ct@flyingcircus.io>
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Subject: nfs4_schedule_state_manager stuck in tight loop
Message-Id: <8B04DA70-ABEF-44A4-BBA7-60968E6CFA10@flyingcircus.io>
Date: Fri, 23 Feb 2024 14:59:49 +0100
Cc: linux-kernel@vger.kernel.org,
 Linux regressions mailing list <regressions@lists.linux.dev>
To: linux-nfs@vger.kernel.org,
 chuck.lever@oracle.com,
 jlayton@kernel.org

Hi,

unfortunately I=E2=80=99m a bit light on details, but willing to provide =
better diagnostics as this moves along.

We=E2=80=99ve had two instances of NFS clients getting stuck with a =
kernel thread spinning around `nfs4_schedule_state_manager` AFAICT:

The first instance of this was last September on a Qemu VM running a =
6.1.45 guest:

root 315344 44.5 0.0 0 0 ? D Sep05 781:38 \_ [172.22.56.83-manager]

It happened a second time in last December on another VM that was likely =
running 5.15.139. (We downgraded our fleet due to other stability issues =
from 6.1 to 5.15 in between those two incidents.)

My colleagues told me that no issues were visible in the logs at that =
time, the systems were generally usable but interacting with anything on =
NFS was (obviously) stuck. So apparently no (soft-) lock ups and no =
stalls were recorded, but I=E2=80=99ll ask my colleagues to either alert =
me or provide all of the logging they can get the next time this =
happens.

Cheers,
Christian

PS: I=E2=80=99ve also recorded this in =
https://bugzilla.kernel.org/show_bug.cgi?id=3D217877 but switching to =
mail-based workflow now.

--=20
Christian Theune =C2=B7 ct@flyingcircus.io =C2=B7 +49 345 219401 0
Flying Circus Internet Operations GmbH =C2=B7 https://flyingcircus.io
Leipziger Str. 70/71 =C2=B7 06108 Halle (Saale) =C2=B7 Deutschland
HR Stendal HRB 21169 =C2=B7 Gesch=C3=A4ftsf=C3=BChrer: Christian Theune, =
Christian Zagrodnick