linux-kernel - hammering timers cause soft lockup?

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Message-ID: <CAK-6q+i_r3obNeD=DLMRp704pnoSEgeMAv3EcMCg-r0_nxM9Dg@mail.gmail.com>
Date: Wed, 27 Mar 2024 11:48:43 -0400
From: Alexander Aring <aahringo@...hat.com>
To: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: hammering timers cause soft lockup?

Hi,

I am currently trying to debug a timer issue on v6.9-rc1 and was able
to write a small reproducer module [0]. If this module gets loaded I
run into a soft lockup e.g. [1]. As far I see several concurrent
timers are getting soft lockups.

As far as I know, I am not doing anything wrong in my timer module
[2]. Please somebody correct me if I am wrong. It does not do much,
except hammering timers. I tried a longterm kernel v6.6.23 and still
have issues.

I appreciate any help somebody can provide.

Thanks.

- Alex

[0] https://gitlab.com/netcoder/timer_softlock
[1] https://gitlab.com/netcoder/timer_softlock/-/blob/main/calltrace_softlockup
[2] https://gitlab.com/netcoder/timer_softlock/-/blob/main/timer_softlock.c