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Date: Fri, 26 Mar 2010 18:23:54 +0100 From: Frederic Weisbecker <fweisbec@...il.com> To: Mike Galbraith <efault@....de> Cc: Li Zefan <lizf@...fujitsu.com>, LKML <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...e.hu>, Peter Zijlstra <peterz@...radead.org>, Arnaldo Carvalho de Melo <acme@...hat.com>, Paul Mackerras <paulus@...ba.org> Subject: Re: [BUG] perf: hard lockup when using perf-sched On Fri, Mar 26, 2010 at 11:11:33AM +0100, Mike Galbraith wrote: > On Thu, 2010-03-25 at 10:27 +0100, Mike Galbraith wrote: > > On Thu, 2010-03-25 at 16:04 +0800, Li Zefan wrote: > > > Mike Galbraith wrote: > > > > On Wed, 2010-03-24 at 08:32 +0100, Mike Galbraith wrote: > > > > > > > >> I just saw this, hunted down your testcase and tried it here. Looks > > > >> like perf_output_lock() wedged box. > > > > > > > > (turns on frame pointers, and adds noinline) > > > > > > > > > > Thanks! Then who's going to fix this... > > > > Well, that kinda depends on whether I figure out how the heck it's all > > supposed to work before somebody else whacks it or not. > > This seems to work, in contrast to everything I tried yesterday. Not > exactly a thing of beauty, but at least it's an option, so... > > perf: fix perf sched record forkbomb deadlock > > perf sched record can deadlock a box should the holder of handle->data->lock > take an interrupt, and then attempt to acquire an rq lock held by a CPU trying > to acquire the same lock. Disable interrupts. Aah. So the scenario is the following inversion? CPU0 CPU1 sched event with rq->lock held grab handle->data->lock spin on handle->data->lock interrupt try to grab rq->lock -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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