Messages in this thread | | | Date | Thu, 2 Oct 2014 14:24:09 -0400 | From | Dave Jones <> | Subject | Re: hrtimer deadlock caused by nohz_full |
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On Fri, Sep 26, 2014 at 01:46:59AM +0200, Frederic Weisbecker wrote:
> > > [<ffffffffa10f95f8>] hrtimer_try_to_cancel+0x58/0x1f0 > > > [<ffffffffa10f97aa>] hrtimer_cancel+0x1a/0x30 > > > [<ffffffffa110a0e7>] tick_nohz_restart+0x17/0x90 > > > [<ffffffffa110af38>] __tick_nohz_full_check+0xc8/0xe0 > > > [<ffffffffa110af5e>] nohz_full_kick_work_func+0xe/0x10 > > > [<ffffffffa117c9bf>] irq_work_run_list+0x4f/0x70 > > > [<ffffffffa117ca0a>] irq_work_run+0x2a/0x60 > > > [<ffffffffa10f82eb>] update_process_times+0x5b/0x70 > > > [<ffffffffa1109dc5>] tick_sched_handle.isra.21+0x25/0x60 > > > [<ffffffffa110a0b1>] tick_sched_timer+0x41/0x60 > > > [<ffffffffa10f8c71>] __run_hrtimer+0x81/0x480 > > > [<ffffffffa110a070>] ? tick_sched_do_timer+0x90/0x90 > > > [<ffffffffa10f9b27>] hrtimer_interrupt+0x107/0x260 > > > [<ffffffffa10331a4>] local_apic_timer_interrupt+0x34/0x60 > > > [<ffffffffa182734f>] smp_apic_timer_interrupt+0x3f/0x60 > > > [<ffffffffa182576f>] apic_timer_interrupt+0x6f/0x80 > > > > hrtimer_interrupt > > tick_sched_timer > > tick_sched_handle > > update_process_times > > irq_work_run > > irq_work_run_list > > nohz_full_kick_work_func > > __tick_nohz_full_check > > tick_nohz_restart > > hrtimer_cancel > > > > And that hrtimer_cancel is: > > > > static void tick_nohz_restart(struct tick_sched *ts, ktime_t now) > > { > > hrtimer_cancel(&ts->sched_timer); > > > > Now, that's really bad because we are in the timer callback of > > ts->sched_timer. So hrtimer_cancel will loop forever waiting for the > > callback to complete. > > > > Frederic !?!? > > Right, this patchset fixes it: "[PATCH 0/8] nohz: Fix nohz kick irq work on tick v3" > > I was about to make the pull request, the branch is acked by peterz. > Would you like to pull it? It's all merge window material. > > git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git > nohz/fixes-v3
I'm now hitting this with such regularity that it's preventing me from tracking down other bugs. Can we get this merged soon please ?
Dave
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