From: Peter Zijlstra <peterz@infradead.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: mingo@kernel.org, gkohli@codeaurora.org, tglx@linutronix.de,
mpe@ellerman.id.au, bigeasy@linutronix.de,
linux-kernel@vger.kernel.org, will.deacon@arm.com
Subject: Re: [PATCH 4/4] kthread: Simplify kthread_park() completion
Date: Tue, 12 Jun 2018 14:42:57 +0200 [thread overview]
Message-ID: <20180612124257.GS12198@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20180608095220.GA18941@redhat.com>
On Fri, Jun 08, 2018 at 11:52:20AM +0200, Oleg Nesterov wrote:
> in smpboot_update_cpumask_percpu_thread() can hit a KTHREAD_SHOULD_PARK
> thread? Lets look into kernel test robot's .config:
>
> CONFIG_NR_CPUS=1
>
> Now look at NR_CPUS==1 version of for_each_cpu* helpers:
>
> #define for_each_cpu(cpu, mask) \
> for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask)
Argh, that issue again.
> So even if the "tmp" cpumask is empty the code above always does
>
> smpboot_park_thread(plug_thread, 0);
>
> and hits the already parked kthread.
OK, I'll write a new Changelog.
next prev parent reply other threads:[~2018-06-12 12:43 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-07 12:33 [PATCH 0/4] kthread/smpboot: More fixes Peter Zijlstra
2018-06-07 12:33 ` [PATCH 1/4] kthread, sched: Fix kthread_parkme() (again...) Peter Zijlstra
2018-06-07 12:33 ` [PATCH 2/4] watchdog/softlockup: Replace "watchdog/%u" threads with cpu_stop_work Peter Zijlstra
2018-06-07 14:24 ` Peter Zijlstra
2018-06-07 14:42 ` Peter Zijlstra
2018-06-08 13:57 ` Oleg Nesterov
2018-06-12 12:17 ` Peter Zijlstra
2018-06-07 12:33 ` [PATCH 3/4] smpboot: Remove cpumask from the API Peter Zijlstra
2018-06-07 12:33 ` [PATCH 4/4] kthread: Simplify kthread_park() completion Peter Zijlstra
2018-06-08 9:52 ` Oleg Nesterov
2018-06-12 12:42 ` Peter Zijlstra [this message]
2018-06-25 7:12 ` Peter Zijlstra
2018-06-25 16:53 ` Oleg Nesterov
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