From: Johannes Weiner <hannes@cmpxchg.org>
To: Michal Hocko <mhocko@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
David Rientjes <rientjes@google.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Yong-Taek Lee <ytk.lee@samsung.com>,
linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
Michal Hocko <mhocko@suse.com>
Subject: Re: [PATCH] proc, oom: do not report alien mms when setting oom_score_adj
Date: Tue, 12 Feb 2019 11:08:32 -0500 [thread overview]
Message-ID: <20190212160832.GB14231@cmpxchg.org> (raw)
In-Reply-To: <20190212102129.26288-1-mhocko@kernel.org>
On Tue, Feb 12, 2019 at 11:21:29AM +0100, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
>
> Tetsuo has reported that creating a thousands of processes sharing MM
> without SIGHAND (aka alien threads) and setting
> /proc/<pid>/oom_score_adj will swamp the kernel log and takes ages [1]
> to finish. This is especially worrisome that all that printing is done
> under RCU lock and this can potentially trigger RCU stall or softlockup
> detector.
>
> The primary reason for the printk was to catch potential users who might
> depend on the behavior prior to 44a70adec910 ("mm, oom_adj: make sure
> processes sharing mm have same view of oom_score_adj") but after more
> than 2 years without a single report I guess it is safe to simply remove
> the printk altogether.
>
> The next step should be moving oom_score_adj over to the mm struct and
> remove all the tasks crawling as suggested by [2]
>
> [1] http://lkml.kernel.org/r/97fce864-6f75-bca5-14bc-12c9f890e740@i-love.sakura.ne.jp
> [2] http://lkml.kernel.org/r/20190117155159.GA4087@dhcp22.suse.cz
> Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
> Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
next prev parent reply other threads:[~2019-02-12 16:08 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-12 10:21 [PATCH] proc, oom: do not report alien mms when setting oom_score_adj Michal Hocko
2019-02-12 16:08 ` Johannes Weiner [this message]
2019-02-12 20:56 ` Andrew Morton
2019-02-12 21:07 ` Tetsuo Handa
2019-02-13 1:24 ` Tetsuo Handa
2019-02-13 11:47 ` Michal Hocko
2019-02-15 0:57 ` Tetsuo Handa
2019-02-15 9:37 ` Michal Hocko
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