From: Rik van Riel <riel@fb.com>
To: Tejun Heo <tj@kernel.org>, Peter Zijlstra <peterz@infradead.org>,
"Ingo Molnar" <mingo@redhat.com>
Cc: <linux-kernel@vger.kernel.org>, <kernel-team@fb.com>
Subject: Re: [PATCH] lockdep: Avoid triggering hardlockup from debug_show_all_locks()
Date: Tue, 23 Jan 2018 14:03:57 -0500 [thread overview]
Message-ID: <1516734237.31954.17.camel@fb.com> (raw)
In-Reply-To: <20180122220055.GB1771050@devbig577.frc2.facebook.com>
On Mon, 2018-01-22 at 14:00 -0800, Tejun Heo wrote:
> debug_show_all_locks() iterates all tasks and print held locks whole
> holding tasklist_lock. This can take a while on a slow console
> device
> and may end up triggering NMI hardlockup detector if someone else
> ends
> up waiting for tasklist_lock.
>
> Touch the NMI watchdog while printing the held locks to avoid
> spuriously triggering the hardlockup detector.
>
> Signed-off-by: Tejun Heo <tj@kernel.org>
On this patch:
Acked-by: Rik van Riel <riel@surriel.com>
However, it seems like we run into things like
this on a fairly regular (though not very frequent)
basis. Would it make sense to go through the code
and add sprinkle around a few more touch_nmi_watchdog()
calls?
After all, there are maybe a few dozen places where
we print out a lot of debugging information.
next prev parent reply other threads:[~2018-01-23 19:05 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-22 22:00 [PATCH] lockdep: Avoid triggering hardlockup from debug_show_all_locks() Tejun Heo
2018-01-23 19:03 ` Rik van Riel [this message]
2018-01-23 20:57 ` Tejun Heo
2018-01-23 21:00 ` Steven Rostedt
2018-01-23 21:11 ` Tejun Heo
2018-01-24 2:49 ` Sergey Senozhatsky
2018-01-24 2:54 ` Steven Rostedt
2018-01-24 5:00 ` Sergey Senozhatsky
2018-01-24 19:10 ` Tejun Heo
2018-01-24 10:38 ` [tip:locking/urgent] locking/lockdep: " tip-bot for Tejun Heo
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