Re: rcu stalls during fstests runs for xfs

[Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com>]

On Feb 06, 2026 / 10:33, Matthieu Baerts wrote:
> Hi Shinichiro,
> 
> Sorry to jump in, but I *think* our CI for the MPTCP subsystem is
> hitting the same issue.

Hi Matthieu,

> On 30/01/2026 12:16, Shinichiro Kawasaki wrote:
> > On Jan 29, 2026 / 15:19, Paul E. McKenney wrote:
> > [...]
> >>>>> I have seen the static-key pattern called out by Dave Chinner when running
> >>>>> KASAN on large systems.  We worked around this by disabling KASAN's use
> >>>>> of static keys.  In case you were running KASAN in these tests.
> >>>>
> >>>> As to KASAN, yes, I enable it in my test runs. I find three static-keys under
> >>>> mm/kasan/*. I will think if they can be disabled in my test runs. Thanks.
> >>>
> >>> There is a set of Kconfig options that disables static branches.  If you
> >>> cannot find them quickly, please let me know and I can look them up.
> > 
> > Thank you. But now I know the fix series by Thomas is available. I prioritize
> > the evaluation of the fix series. Later on, I will try disabling the static-keys
> > if it is required.
> > 
> >>
> >> And Thomas Gleixner posted an alleged fix to the CID issue here:
> >>
> >> https://lore.kernel.org/lkml/20260129210219.452851594@kernel.org/
> >>
> >> Please let him know whether or not it helps.
> > 
> > Good to see this fix candidate series, thanks :) I have set up the patches and
> > started my regular test runs. So far, the hangs have been observed once or twice
> > a week. To confirm the effect of the fix series, I think two weeks runs will be
> > required. Once I get the result, will share it on this thread and with Thomas.
> 
> I know it is only one week now, but did you see any effects so far?

No, I do not see any hang so far. And I hope there will be no hang in the
next week either. Fingers crossed...

> On
> my side, I applied the v2 series -- which has been applied i
> tip/sched/urgent -- but I still have issues, and it looks like it is
> even more frequent. Maybe what I see is different. If you no longer see
> the issues on your side after one week, I'm going to start a new thread
> with my issues not to mix them.
> 
> Note that in my case, the issue is visible on a system where nested VMs
> are used, with and without KASAN (enabled via debug.config), just after
> having started a VSOCK listening socket via socat.

I applied the v1 series on top of my test target xfs kernel branches enabling
KASAN.