Message-ID: <20141009033017.GA24907@lerouge>
Date:	Thu, 9 Oct 2014 05:30:20 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Dave Jones <davej@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: hrtimer deadlock caused by nohz_full

On Wed, Oct 08, 2014 at 10:02:40PM -0400, Dave Jones wrote:
> On Tue, Oct 07, 2014 at 07:42:47PM +0200, Thomas Gleixner wrote:
>  > On Tue, 7 Oct 2014, Dave Jones wrote:
>  > 
>  > > On Tue, Oct 07, 2014 at 05:30:27PM +0200, Frederic Weisbecker wrote:
>  > > 
>  > >  > >  > 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 ?
>  > >  > 
>  > >  > I asked Thomas to pull but he probably missed it. So I did a formal pull request
>  > >  > to Ingo a few days later but he told me that the pull request was made too late
>  > >  > as the merge window was too close. I told him it fixes annoying bugs but that was on IRC
>  > >  > so this probably got lost.
>  > 
>  > Aarg. Lemme get this done.
> 
> So, time for sad news.
> This still doesn't solve the problem for me.
> 
> Kernel panic - not syncing: Watchdog detected hard LOCKUP on cpu 2
> CPU: 2 PID: 8193 Comm: kworker/u8:1 Not tainted 3.17.0+ #67
> Workqueue: netns cleanup_net
>  0000000000000000 000000002a473fb8 ffff880244c06c00 ffffffff9f81ea56
>  ffffffff9fc63e00 ffff880244c06c80 ffffffff9f819003 0000000000000010
>  ffff880244c06c90 ffff880244c06c30 000000002a473fb8 0000000000000000
> Call Trace:
>  <NMI>  [<ffffffff9f81ea56>] dump_stack+0x4e/0x7a
>  [<ffffffff9f819003>] panic+0xd7/0x20a
>  [<ffffffff9f149f30>] ? restart_watchdog_hrtimer+0x50/0x50
>  [<ffffffff9f14a048>] watchdog_overflow_callback+0x118/0x120
>  [<ffffffff9f18b69c>] __perf_event_overflow+0xac/0x350
>  [<ffffffff9f019ece>] ? x86_perf_event_set_period+0xde/0x150
>  [<ffffffff9f18c5b4>] perf_event_overflow+0x14/0x20
>  [<ffffffff9f01fc26>] intel_pmu_handle_irq+0x206/0x410
>  [<ffffffff9f018d2b>] perf_event_nmi_handler+0x2b/0x50
>  [<ffffffff9f007752>] nmi_handle+0xd2/0x3b0
>  [<ffffffff9f007685>] ? nmi_handle+0x5/0x3b0
>  [<ffffffff9f0cef39>] ? get_lock_stats+0x19/0x60
>  [<ffffffff9f007c62>] default_do_nmi+0x72/0x1c0
>  [<ffffffff9f0fd318>] ? hrtimer_try_to_cancel+0x58/0x1f0
>  [<ffffffff9f007e68>] do_nmi+0xb8/0xf0
>  [<ffffffff9f82c9ea>] end_repeat_nmi+0x1e/0x2e
>  [<ffffffff9f0fd318>] ? hrtimer_try_to_cancel+0x58/0x1f0
>  [<ffffffff9f0cef39>] ? get_lock_stats+0x19/0x60
>  [<ffffffff9f0cef39>] ? get_lock_stats+0x19/0x60
>  [<ffffffff9f0cef39>] ? get_lock_stats+0x19/0x60
>  <<EOE>>  <IRQ>  [<ffffffff9f0cf880>] lock_release_holdtime.part.29+0x50/0x160
>  [<ffffffff9f0d4f75>] lock_release+0x235/0x300
>  [<ffffffff9f829bf4>] _raw_spin_unlock_irqrestore+0x24/0x70
>  [<ffffffff9f0fd318>] hrtimer_try_to_cancel+0x58/0x1f0
>  [<ffffffff9f0fd4ca>] hrtimer_cancel+0x1a/0x30
>  [<ffffffff9f10de07>] tick_nohz_restart+0x17/0x90
>  [<ffffffff9f10ec58>] __tick_nohz_full_check+0xc8/0xe0
>  [<ffffffff9f10ec7e>] nohz_full_kick_work_func+0xe/0x10
>  [<ffffffff9f1806df>] irq_work_run_list+0x4f/0x70
>  [<ffffffff9f18091b>] irq_work_tick+0x2b/0x50
>  [<ffffffff9f0fc00b>] update_process_times+0x5b/0x70
>  [<ffffffff9f10dae5>] tick_sched_handle.isra.21+0x25/0x60
>  [<ffffffff9f10ddd1>] tick_sched_timer+0x41/0x60
>  [<ffffffff9f0fc991>] __run_hrtimer+0x81/0x480
>  [<ffffffff9f10dd90>] ? tick_sched_do_timer+0x90/0x90
>  [<ffffffff9f0fd847>] hrtimer_interrupt+0x107/0x260
>  [<ffffffff9f033274>] local_apic_timer_interrupt+0x34/0x60
>  [<ffffffff9f82d48f>] smp_apic_timer_interrupt+0x3f/0x60
>  [<ffffffff9f82b8af>] apic_timer_interrupt+0x6f/0x80
>  <EOI>  [<ffffffffc0415436>] ? cache_clean+0x66/0x2f0 [sunrpc]
>  [<ffffffffc04156f7>] cache_flush+0x37/0x70 [sunrpc]
>  [<ffffffffc041577f>] cache_purge+0x4f/0x80 [sunrpc]
>  [<ffffffffc040c80a>] svcauth_unix_purge+0xca/0x1c0 [sunrpc]
>  [<ffffffffc040c745>] ? svcauth_unix_purge+0x5/0x1c0 [sunrpc]
>  [<ffffffffc04d4f72>] nfsd_export_shutdown+0x112/0x250 [nfsd]
>  [<ffffffffc04d4e65>] ? nfsd_export_shutdown+0x5/0x250 [nfsd]
>  [<ffffffffc04c972a>] nfsd_exit_net+0x1a/0x20 [nfsd]
>  [<ffffffff9f6cdf39>] ops_exit_list.isra.1+0x39/0x60
>  [<ffffffff9f6ceae0>] cleanup_net+0x100/0x1e0
>  [<ffffffff9f097b30>] process_one_work+0x1e0/0x6b0
>  [<ffffffff9f097ac7>] ? process_one_work+0x177/0x6b0
>  [<ffffffff9f09811b>] worker_thread+0x11b/0x490
>  [<ffffffff9f098000>] ? process_one_work+0x6b0/0x6b0
>  [<ffffffff9f09ee46>] kthread+0xf6/0x110
>  [<ffffffff9f09ed50>] ? kthread_create_on_node+0x250/0x250
>  [<ffffffff9f82a8ac>] ret_from_fork+0x7c/0xb0
>  [<ffffffff9f09ed50>] ? kthread_create_on_node+0x250/0x250
> 
> Here's what I have on top of Linus' current tree..
> http://paste.fedoraproject.org/140505/20075141/raw/
> 
> Do I miss some other essential patch ?

If you have used the diff in that URL then you've missed:

     x86: Tell irq work about self IPI support

Without that the whole patchset has no effect.
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