From: Steven Rostedt <rostedt@goodmis.org>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Tejun Heo <htejun@gmail.com>, Vlastimil Babka <vbabka@suse.cz>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
tglx@linutronix.de, "Steven J . Hill" <steven.hill@cavium.com>,
Andrew Morton <akpm@linux-foundation.org>,
Christoph Lameter <cl@linux.com>
Subject: Re: [PATCH] Revert mm/vmstat.c: fix vmstat_update() preemption BUG
Date: Wed, 27 Jun 2018 08:36:57 -0400 [thread overview]
Message-ID: <20180627123657.2hb7ow4szjyhg5aj@home.goodmis.org> (raw)
In-Reply-To: <20180411190729.7sbmbsxtkcng7ddx@linutronix.de>
On Wed, Apr 11, 2018 at 09:07:30PM +0200, Sebastian Andrzej Siewior wrote:
>
> This already happens:
> - vmstat_shepherd() does get_online_cpus() and within this block it does
> queue_delayed_work_on(). So this has to wait until cpuhotplug
> completed before it can schedule something and then it won't schedule
> anything on the "off" CPU.
But can't we have something like this happen: ?
CPU0 CPU1 CPU2
---- ---- ----
get_online_cpus()
queue_work(vmstat_update, cpu1)
wakeup(kworker/1)
High prio task running
put_online_cpus()
Shutdown CPU 1
migrate kworker/1
schedule kworker/1
(smp_processor_id() != 1)
-- Steve
next prev parent reply other threads:[~2018-06-27 12:37 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-11 9:57 [PATCH] Revert mm/vmstat.c: fix vmstat_update() preemption BUG Sebastian Andrzej Siewior
2018-04-11 13:56 ` Vlastimil Babka
2018-04-11 14:09 ` Tejun Heo
2018-04-11 14:42 ` Sebastian Andrzej Siewior
2018-04-11 19:07 ` Sebastian Andrzej Siewior
2018-04-18 15:44 ` Sebastian Andrzej Siewior
2018-04-18 19:54 ` Andrew Morton
2018-06-27 12:36 ` Steven Rostedt [this message]
2018-06-27 12:47 ` Sebastian Andrzej Siewior
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