From: Peter Zijlstra <peterz@infradead.org>
To: Waiman Long <longman@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>, Will Deacon <will.deacon@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org,
Bart Van Assche <bvanassche@acm.org>
Subject: Re: [PATCH 0/2] locking/lockdep: Track number of zapped classes & report abuse
Date: Thu, 29 Nov 2018 23:48:36 +0100 [thread overview]
Message-ID: <20181129224836.GI11632@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <1543531297-18349-1-git-send-email-longman@redhat.com>
On Thu, Nov 29, 2018 at 05:41:35PM -0500, Waiman Long wrote:
> When a kernel module is repeatedly load and unload, it will eventually
> exhaust the lockdep entries resulting in a bug message. This is a use
> case that the current lockdep code cannot support.
>
> This patchset tracks the number of zapped classes and print a warning if
> too many lockdep entries are wasted because of too many module unloading.
> For example,
>
> [ 2490.651531] BUG: MAX_LOCKDEP_KEYS too low!
> [ 2490.669925] turning off the locking correctness validator.
> [ 2490.669925] Please attach the output of /proc/lock_stat to the bug report
> [ 2490.669926] ========================================================
> [ 2490.669927] WARNING: 6499 out of 8191 locks have been destroyed
> [ 2490.669927] through kernel module unload operations.
> [ 2490.669928] The corresponding lockdep entries are not reusable.
> [ 2490.669928] The system might have run out of lockdep entries because
> [ 2490.669929] of repeated kernel module load and unload operations.
> [ 2490.669929] Lockdep cannot support this particular use case.
> [ 2490.669930] --------------------------------------------------------
Have a look here:
https://lkml.kernel.org/r/20181128234325.110011-1-bvanassche@acm.org
next prev parent reply other threads:[~2018-11-29 22:48 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-29 22:41 Waiman Long
2018-11-29 22:41 ` [PATCH 1/2] locking/lockdep: Annotate #else/#endif's that are far from #if Waiman Long
2018-11-29 22:41 ` [PATCH 2/2] locking/lockdep: Track number of zapped classes & report abuse Waiman Long
2018-11-29 22:48 ` Peter Zijlstra [this message]
2018-11-30 14:38 ` [PATCH 0/2] " Waiman Long
2018-12-05 15:37 ` Waiman Long
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