Re: lockdep trace from posix timers

From: Dave Jones
Date: Fri Jul 27 2012 - 12:20:51 EST


On Tue, Jul 24, 2012 at 04:36:13PM -0400, Dave Jones wrote:
> Linus tree as of 5fecc9d8f59e765c2a48379dd7c6f5cf88c7d75a
>
> Dave
>
> ======================================================
> [ INFO: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected ]
> 3.5.0+ #122 Not tainted
> ------------------------------------------------------
> trinity-child2/5327 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
> blocked: (tasklist_lock){.+.+..}, instance: ffffffff81c05098, at: [<ffffffff8109762b>] posix_cpu_timer_del+0x2b/0xe0
>
> and this task is already holding:
> blocked: (&(&new_timer->it_lock)->rlock){-.-...}, instance: ffff880143bce170, at: [<ffffffff81093d49>] __lock_timer+0x89/0x1f0
> which would create a new lock dependency:
> (&(&new_timer->it_lock)->rlock){-.-...} -> (tasklist_lock){.+.+..}
>
> but this new dependency connects a HARDIRQ-irq-safe lock:
> (&(&new_timer->it_lock)->rlock){-.-...}
> ... which became HARDIRQ-irq-safe at:

Shall I start bisecting this ? I can trigger it very easily, but if you
can give me a set of commits to narrow down, it'll speed up the bisection.

Dave
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