From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
To: Qian Cai <cai@lca.pw>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
juri.lelli@redhat.com, vincent.guittot@linaro.org,
dietmar.eggemann@arm.com,
"Steven Rostedt (VMware)" <rostedt@goodmis.org>,
bsegall@google.com, mgorman@suse.de, paulmck@kernel.org,
tglx@linutronix.de, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] sched/core: fix illegal RCU from offline CPUs
Date: Mon, 13 Jan 2020 17:20:57 +0900 [thread overview]
Message-ID: <66e33eb5-e958-6dc8-2327-4168afdd9e1e@i-love.sakura.ne.jp> (raw)
In-Reply-To: <7168A4A4-E735-4809-B80A-389990603EB8@lca.pw>
On 2020/01/13 15:30, Qian Cai wrote:
>>> - mmdrop(mm);
>>> + smp_call_function_single(cpumask_first(cpu_online_mask),
>>> + (void (*)(void *))mmdrop, mm, 0);
>>
>> mmdrop() might sleep, but
>
> If that is the case, and then the commit e78a7614f387 (“idle: Prevent
> late-arriving interrupts from disrupting offline”) is incorrect because it
> will disable local irq before calling mmdrop() which will trigger
> the might_sleep() warning. Can you prove it?
Is commit 7283094ec3db318e ("kernel, oom: fix potential pgd_lock deadlock from
__mmdrop") about only softirq? Is it guaranteed that smp_call_function_single()
does not hit such race? Then just my overcareful...
next prev parent reply other threads:[~2020-01-13 8:21 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-12 16:17 [PATCH] sched/core: fix illegal RCU from offline CPUs Qian Cai
2020-01-13 0:33 ` Tetsuo Handa
2020-01-13 6:30 ` Qian Cai
2020-01-13 8:20 ` Tetsuo Handa [this message]
2020-01-13 13:42 ` Qian Cai
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