linux-kernel - Re: [tip:locking/futex] [futex] 56180dd20c: BUG:sleeping_function_called_from_invalid_context_at

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Message-ID: <87a54usty4.ffs@tglx>
Date: Wed, 23 Jul 2025 19:22:43 +0200
From: Thomas Gleixner <tglx@...utronix.de>
To: kernel test robot <oliver.sang@...el.com>, Peter Zijlstra
 <peterz@...radead.org>
Cc: oe-lkp@...ts.linux.dev, lkp@...el.com, linux-kernel@...r.kernel.org,
 x86@...nel.org, Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
 linux-mm@...ck.org, ltp@...ts.linux.it, oliver.sang@...el.com
Subject: Re: [tip:locking/futex] [futex]  56180dd20c:
 BUG:sleeping_function_called_from_invalid_context_at_kernel/nsproxy.c

On Wed, Jul 23 2025 at 16:46, kernel test robot wrote:
> kernel test robot noticed "BUG:sleeping_function_called_from_invalid_context_at_kernel/nsproxy.c" on:
>
> commit: 56180dd20c19e5b0fa34822997a9ac66b517e7b3 ("futex: Use RCU-based per-CPU reference counting instead of rcuref_t")
> https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git locking/futex
>
> the issue (1)(2) happen randomly upon 56180dd20c.

Hmm.

> a255b78d14324f8a 56180dd20c19e5b0fa34822997a
> ---------------- ---------------------------
>        fail:runs  %reproduction    fail:runs
>            |             |             |
>            :50          48%          24:50    dmesg.BUG:scheduling_while_atomic    <---- (2)
>            :50          48%          24:50    dmesg.BUG:sleeping_function_called_from_invalid_context_at_kernel/nsproxy.c   <---- (1)
>          50:50           0%          50:50    dmesg.Mem-Info
>          50:50           0%          50:50    dmesg.invoked_oom-killer:gfp_mask=0x
>
>
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <oliver.sang@...el.com>
> | Closes: https://lore.kernel.org/oe-lkp/202507231021.dcf24373-lkp@intel.com
>
>
> [  286.673775][   C97] BUG: sleeping function called from invalid context at kernel/nsproxy.c:233   <---- (1)
> [  286.673784][   C97] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 6748, name: oom03
> [  286.673787][   C97] preempt_count: 7ffffffe, expected: 0

Ooops. That's a corrupted preempt counter, which has underflown twice.

Can you please enable CONFIG_DEBUG_PREEMPT, so we can see where this
happens?

Thanks,

        tglx