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b2b469939e
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 44a70adec9 ("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
Link: http://lkml.kernel.org/r/20190212102129.26288-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Yong-Taek Lee <ytk.lee@samsung.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.