Re: sched: circular dependency between sched_domains_mutex andoom_notify_list

From: Ingo Molnar
Date: Mon Feb 18 2013 - 03:26:50 EST



* Sasha Levin <sasha.levin@xxxxxxxxxx> wrote:

> I suspect it's the result of adding the new rcu_oom_notify, but that happened
> about half a year ago so I'm not sure why this showed up only now.
>
> [ 1039.634183] ======================================================
> [ 1039.635717] [ INFO: possible circular locking dependency detected ]
> [ 1039.637255] 3.8.0-rc7-next-20130215-sasha-00003-gea816fa #286 Tainted: G W
> [ 1039.639104] -------------------------------------------------------
> [ 1039.640579] init/1 is trying to acquire lock:
> [ 1039.641224] ((oom_notify_list).rwsem){.+.+..}, at: [<ffffffff81141c8f>] __blocking_notifier_call_chain+0x7f/0xc0

We changed (optimized) rwsems via:

3a15e0e0cdda rwsem: Implement writer lock-stealing for better scalability

so maybe it can hit different codepaths and races now?

Thanks,

Ingo
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