kernel-packages team mailing list archive

[Sergio Gelato <Sergio.Gelato@xxxxxxxxxxx>]

So far, this particular symptom has been seen exactly once. The host it
was observed on was reinstalled from scratch with trusty a few weeks ago
following a hard disk failure, so no dist-upgrade involved. I did some
NFS-client-related tuning on this and many other machines this week so
it's conceivable that this has caused new code paths to be exercised
(although the changes were rather benign: a longer credential timeout in
rpc.gssd, an explicit port number for nfs.nfs_callback_tcpport, a
smaller value for auth_rpcgss.key_expire_timeo, and only the rpc.gssd
change had actually taken effect on that host at the time of the
incident).

I've looked at the source code "for kthread_run" (or rather the function
behind that macro). The error is the result of a memory allocation
failure. What caused the kernel to run out of memory (this machine has
32GB of RAM, by the way) last night is probably unknowable at this
point, and need not have had anything to do with NFS. *This* bug report
is only about the fact that the issuing of that particular error message
(from fs/nfs/nfs4state.c:nfs4_schedule_state_manager()) is not rate-
limited (neither in 3.13 nor in the linux-stable tree at
git.kernel.org), which put an undesirable load on my syslog
infrastructure. That should be easy to fix: it's what
pr_warn_ratelimited() is for.

I cannot reproduce the symptom at will, so I won't actually test the
kernel from vivid: any negative result would be inconclusive. Since I
know from reading the source code that the message is still not rate-
limited upstream, I assume that kernel-bug-exists-upstream is the right
choice.

** Tags added: kernel-bug-exists-upstream

** Changed in: linux (Ubuntu)
       Status: Incomplete => Confirmed

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https://bugs.launchpad.net/bugs/1423472

Title:
  Logs flooded with "nfs4_schedule_state_manager: kthread_run: -12"

Status in linux package in Ubuntu:
  Confirmed

Bug description:
  An NFSv4 client running kernel 3.13.0-44-generic #73-Ubuntu (amd64) suddenly started spewing
     nfs4_schedule_state_manager: kthread_run: -12
  log messages at an average rate of 2.65 kHz. It did not stop until I rebooted it.

  At the very least that message needs to be rate-limited. (Doesn't seem
  to be fixed upstream yet.)

  As for the underlying problem, -12 is -ENOMEM. I'm afraid I have no
  idea why the kernel ran out of memory at that point. WIll follow up if
  the problem ever recurs. This bug report is mainly about the lack of
  rate limiting.

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