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From: Vasily Gorbik <gor@linux.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>, Miroslav Benes <mbenes@suse.cz>
Cc: jpoimboe@redhat.com, jikos@kernel.org, pmladek@suse.com,
	mingo@kernel.org, linux-kernel@vger.kernel.org,
	joe.lawrence@redhat.com, fweisbec@gmail.com, tglx@linutronix.de,
	hca@linux.ibm.com, svens@linux.ibm.com, sumanthk@linux.ibm.com,
	live-patching@vger.kernel.org, paulmck@kernel.org,
	rostedt@goodmis.org, x86@kernel.org
Subject: Re: [PATCH v2 05/11] sched,livepatch: Use wake_up_if_idle()
Date: Thu, 7 Oct 2021 11:18:13 +0200	[thread overview]
Message-ID: <your-ad-here.call-01633598293-ext-3109@work.hours> (raw)
In-Reply-To: <alpine.LSU.2.21.2110061115270.2311@pobox.suse.cz>

On Wed, Oct 06, 2021 at 11:16:21AM +0200, Miroslav Benes wrote:
> On Wed, 29 Sep 2021, Peter Zijlstra wrote:
> 
> > Make sure to prod idle CPUs so they call klp_update_patch_state().
> > 
> > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> > ---
> >  kernel/livepatch/transition.c |    5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> > --- a/kernel/livepatch/transition.c
> > +++ b/kernel/livepatch/transition.c
> > @@ -413,8 +413,11 @@ void klp_try_complete_transition(void)
> >  	for_each_possible_cpu(cpu) {
> >  		task = idle_task(cpu);
> >  		if (cpu_online(cpu)) {
> > -			if (!klp_try_switch_task(task))
> > +			if (!klp_try_switch_task(task)) {
> >  				complete = false;
> > +				/* Make idle task go through the main loop. */
> > +				wake_up_if_idle(cpu);
> > +			}
> 
> Right, it should be enough.
> 
> Acked-by: Miroslav Benes <mbenes@suse.cz>
> 
> It would be nice to get Vasily's Tested-by tag on this one.

I gave patches a spin on s390 with livepatch kselftest as well as with
https://github.com/lpechacek/qa_test_klp.git

BTW, commit 43c79fbad385 ("klp_tc_17: Avoid running the test on
s390x") is no longer required, since s390 implements HAVE_KPROBES_ON_FTRACE
since v5.6, so I just reverted test disablement.

Patches 1-6 work nicely, for them

Acked-by: Vasily Gorbik <gor@linux.ibm.com>
Tested-by: Vasily Gorbik <gor@linux.ibm.com> # on s390

Thanks a lot!

Starting with patch 8 is where I start seeing this with my config:

Oct 07 10:46:00 kernel: Freeing unused kernel image (initmem) memory: 6524K
Oct 07 10:46:00 kernel: INFO: task swapper/0:1 blocked for more than 122 seconds.
Oct 07 10:46:00 kernel:       Not tainted 5.15.0-rc4-69810-ga714851e1aad-dirty #74
Oct 07 10:46:00 kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Oct 07 10:46:00 kernel: task:swapper/0       state:D stack:10648 pid:    1 ppid:     0 flags:0x00000000
Oct 07 10:46:00 kernel: Call Trace:
Oct 07 10:46:00 kernel:  [<0000000000e164b6>] __schedule+0x36e/0x8b0
Oct 07 10:46:00 kernel:  [<0000000000e16a4e>] schedule+0x56/0x128
Oct 07 10:46:00 kernel:  [<0000000000e1e426>] schedule_timeout+0x106/0x160
Oct 07 10:46:00 kernel:  [<0000000000e18316>] wait_for_completion+0xc6/0x118
Oct 07 10:46:00 kernel:  [<000000000020a15c>] rcu_barrier.part.0+0x17c/0x2c0
Oct 07 10:46:00 kernel:  [<0000000000e0fcc0>] kernel_init+0x60/0x168
Oct 07 10:46:00 kernel:  [<000000000010390c>] __ret_from_fork+0x3c/0x58
Oct 07 10:46:00 kernel:  [<0000000000e2094a>] ret_from_fork+0xa/0x30
Oct 07 10:46:00 kernel: 1 lock held by swapper/0/1:
Oct 07 10:46:00 kernel:  #0: 0000000001469600 (rcu_state.barrier_mutex){+.+.}-{3:3}, at: rcu_barrier+0x42/0x80
Oct 07 10:46:00 kernel:
                        Showing all locks held in the system:
Oct 07 10:46:00 kernel: 1 lock held by swapper/0/1:
Oct 07 10:46:00 kernel:  #0: 0000000001469600 (rcu_state.barrier_mutex){+.+.}-{3:3}, at: rcu_barrier+0x42/0x80
Oct 07 10:46:00 kernel: 2 locks held by kworker/u680:0/8:
Oct 07 10:46:00 kernel:  #0: 000000008013cd48 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x222/0x738
Oct 07 10:46:00 kernel:  #1: 0000038000043dc8 ((kfence_timer).work){+.+.}-{0:0}, at: process_one_work+0x222/0x738
Oct 07 10:46:00 kernel: 1 lock held by khungtaskd/413:
Oct 07 10:46:00 kernel:  #0: 000000000145c980 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire.constprop.0+0x0/0x50
Oct 07 10:46:00 kernel:
Oct 07 10:46:00 kernel: =============================================

So, will keep an eye on the rest of these patches and re-test in future, thanks!

  reply	other threads:[~2021-10-07  9:19 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-29 15:17 [PATCH v2 00/11] sched,rcu,context_tracking,livepatch: Improve livepatch task transitions for idle and NOHZ_FULL Peter Zijlstra
2021-09-29 15:17 ` [PATCH v2 01/11] sched: Improve try_invoke_on_locked_down_task() Peter Zijlstra
2021-09-29 15:17 ` [PATCH v2 02/11] sched,rcu: Rework try_invoke_on_locked_down_task() Peter Zijlstra
2021-09-29 15:17 ` [PATCH v2 03/11] sched,livepatch: Use task_call_func() Peter Zijlstra
2021-10-05 11:40   ` Petr Mladek
2021-10-05 14:03     ` Peter Zijlstra
2021-10-06  8:59   ` Miroslav Benes
2021-09-29 15:17 ` [PATCH v2 04/11] sched: Simplify wake_up_*idle*() Peter Zijlstra
2021-10-13 14:32   ` Qian Cai
2021-10-19  3:47     ` Qian Cai
2021-10-19  8:56       ` Peter Zijlstra
2021-10-19  9:10         ` Peter Zijlstra
2021-10-19 15:32           ` Qian Cai
2021-10-19 15:50             ` Peter Zijlstra
2021-10-19 19:22               ` Qian Cai
2021-10-19 20:27                 ` Peter Zijlstra
     [not found]   ` <CGME20211022134630eucas1p2e79e2816587d182c580459d567c1f2a9@eucas1p2.samsung.com>
2021-10-22 13:46     ` Marek Szyprowski
2021-09-29 15:17 ` [PATCH v2 05/11] sched,livepatch: Use wake_up_if_idle() Peter Zijlstra
2021-10-05 12:00   ` Petr Mladek
2021-10-06  9:16   ` Miroslav Benes
2021-10-07  9:18     ` Vasily Gorbik [this message]
2021-10-07 10:02       ` Peter Zijlstra
2021-10-13 19:37   ` Arnd Bergmann
2021-10-14 10:42     ` Peter Zijlstra
2021-09-29 15:17 ` [RFC][PATCH v2 06/11] context_tracking: Prefix user_{enter,exit}*() Peter Zijlstra
2021-09-29 15:17 ` [RFC][PATCH v2 07/11] context_tracking: Add an atomic sequence/state count Peter Zijlstra
2021-09-29 15:17 ` [RFC][PATCH v2 08/11] context_tracking,rcu: Replace RCU dynticks counter with context_tracking Peter Zijlstra
2021-09-29 18:37   ` Paul E. McKenney
2021-09-29 19:09     ` Peter Zijlstra
2021-09-29 19:11     ` Peter Zijlstra
2021-09-29 19:13     ` Peter Zijlstra
2021-09-29 19:24       ` Peter Zijlstra
2021-09-29 19:45         ` Paul E. McKenney
2021-09-29 18:54   ` Peter Zijlstra
2021-09-29 15:17 ` [RFC][PATCH v2 09/11] context_tracking,livepatch: Dont disturb NOHZ_FULL Peter Zijlstra
2021-10-06  8:12   ` Petr Mladek
2021-10-06  9:04     ` Peter Zijlstra
2021-10-06 10:29       ` Petr Mladek
2021-10-06 11:41         ` Peter Zijlstra
2021-10-06 11:48         ` Miroslav Benes
2021-09-29 15:17 ` [RFC][PATCH v2 10/11] livepatch: Remove klp_synchronize_transition() Peter Zijlstra
2021-10-06 12:30   ` Petr Mladek
2021-09-29 15:17 ` [RFC][PATCH v2 11/11] context_tracking,x86: Fix text_poke_sync() vs NOHZ_FULL Peter Zijlstra
2021-10-21 18:39   ` Marcelo Tosatti
2021-10-21 18:40     ` Marcelo Tosatti
2021-10-21 19:25     ` Peter Zijlstra
2021-10-21 19:57       ` Marcelo Tosatti
2021-10-21 20:18         ` Peter Zijlstra
2021-10-26 18:19           ` Marcelo Tosatti
2021-10-26 19:38             ` Peter Zijlstra
2021-09-29 18:03 ` [PATCH v2 00/11] sched,rcu,context_tracking,livepatch: Improve livepatch task transitions for idle and NOHZ_FULL Paul E. McKenney

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