From: Mike Galbraith <umgwanakikbuti@gmail.com>
To: Tejun Heo <tj@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>
Subject: mod_delayed_work() explosion due to 874bbfe6
Date: Tue, 02 Feb 2016 15:44:24 +0100 [thread overview]
Message-ID: <1454424264.11183.46.camel@gmail.com> (raw)
Hi Tejun,
I'm looking at a crash analysis that fingers 874bbfe6 as being the
culprit. (I didn't do the analysis, but it appears to be correct)
Scenario: CPU168 calls mod_delayed_work(), is taken offline before the
timer expires. Due to 874bbfe6, dwork->cpu is the now offline CPU168
vs the previous WORK_CPU_UNBOUND, timer fires on CPU131, it tries to
__queue_work() with cpu == the now offline CPU168, gets to...
} else
pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu));
... and goes boom.
<snippet>
crash> p numa_node | grep 168
[168]: ffff8c03fdf0e328
crash> rd ffff8c03fdf0e328
ffff8c03fdf0e328: 00000000ffffffff ........
Thus, pwq becomes 000000000. Then, as the result of reference to
pwq->pool, NULL reference occurs at (*PANIC).
</snippet>
What if anything is supposed to prevent this?
-Mike
next reply other threads:[~2016-02-02 14:44 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-02 14:44 Mike Galbraith [this message]
2016-02-03 14:37 ` Michal Hocko
2016-02-03 16:32 ` Tejun Heo
2016-02-03 18:54 ` [PATCH wq/for-4.5-fixes] workqueue: handle NUMA_NO_NODE for unbound pool_workqueue lookup Tejun Heo
2016-02-03 18:55 ` Tejun Heo
2016-02-04 3:15 ` Mike Galbraith
2016-02-03 19:12 ` Thomas Gleixner
2016-02-03 19:28 ` Tejun Heo
2016-02-04 2:12 ` Mike Galbraith
2016-02-04 8:40 ` Michal Hocko
2016-02-10 15:55 ` Tejun Heo
2016-02-15 17:33 ` Michal Hocko
2016-02-15 18:21 ` Tejun Heo
2016-02-15 20:54 ` Michal Hocko
2016-02-15 21:02 ` Tejun Heo
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