From: Michal Hocko <mhocko@kernel.org>
To: linux-mm@kvack.org
Cc: Andrea Argangeli <andrea@kernel.org>,
Mel Gorman <mgorman@suse.de>,
Johannes Weiner <hannes@cmpxchg.org>,
David Rientjes <rientjes@google.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: why do we do ALLOC_WMARK_HIGH before going out_of_memory
Date: Thu, 28 Jan 2016 17:38:03 +0100 [thread overview]
Message-ID: <20160128163802.GA15953@dhcp22.suse.cz> (raw)
Hi,
__alloc_pages_may_oom just after it manages to get oom_lock we try
to allocate once more with ALLOC_WMARK_HIGH target. I was always
wondering why are we will to actually kill something even though
we are above min wmark. This doesn't make much sense to me. I understand
that this is racy because __alloc_pages_may_oom is called after we have
failed to fulfill the WMARK_MIN target but this means WMARK_HIGH
is highly unlikely as well. So either we should use ALLOC_WMARK_MIN
or get rid of this altogether.
The code has been added before git era by
https://www.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.11-rc2/2.6.11-rc2-mm2/broken-out/mm-fix-several-oom-killer-bugs.patch
and it doesn't explain this particular decision. It seems to me that
what ever was the reason back then it doesn't hold anymore.
What do you think?
--
Michal Hocko
SUSE Labs
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next reply other threads:[~2016-01-28 16:38 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-28 16:38 Michal Hocko [this message]
2016-01-28 19:02 ` Andrea Arcangeli
2016-01-28 20:11 ` Michal Hocko
2016-01-28 21:12 ` Johannes Weiner
2016-01-28 21:55 ` Michal Hocko
2016-01-28 23:40 ` Johannes Weiner
2016-01-29 14:38 ` Michal Hocko
2016-01-29 15:56 ` Andrea Arcangeli
2016-01-29 16:12 ` Michal Hocko
2016-01-29 16:29 ` Michal Hocko
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