From: Rik van Riel <riel@redhat.com>
To: Vlastimil Babka <vbabka@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hughd@google.com>
Cc: linux-mm@kvack.org, Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Rafael Aquini <aquini@redhat.com>
Subject: Re: [PATCH] mm: fix negative nr_isolated counts
Date: Thu, 12 Feb 2015 10:12:30 -0500 [thread overview]
Message-ID: <54DCC2DE.10503@redhat.com> (raw)
In-Reply-To: <54DC61C6.10502@suse.cz>
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On 02/12/2015 03:18 AM, Vlastimil Babka wrote:
> On 02/11/2015 10:09 PM, Andrew Morton wrote:
>>> Fixes: edc2ca612496 ("mm, compaction: move pageblock checks up
>>> from isolate_migratepages_range()") Signed-off-by: Hugh Dickins
>>> <hughd@google.com> Cc: stable@vger.kernel.org # v3.18+
>>
>> And why -stable? What user-visible problem is the bug causing?
>>
>
> Commit 35cd78156c "vmscan: throttle direct reclaim when too many
> pages are isolated already" by Rik seems to have introduced this
> congestion_wait() based on too_many_isolated(). The bug it was
> fixing:
>
> "When way too many processes go into direct reclaim, it is possible
> for all of the pages to be taken off the LRU. One result of this is
> that the next process in the page reclaim code thinks there are no
> reclaimable pages left and triggers an out of memory kill."
>
> So either this is now prevented by something else and
> too_many_isolated() could go away, or we should restore its
> functionality. Any idea, Rik?
I don't think that bug is prevented.
I have seen reports of OOM kills happening while the system
still has a lot of reclaimable page cache pages.
This might actually help explain that bug...
- --
All rights reversed
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prev parent reply other threads:[~2015-02-12 15:12 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-11 7:06 Hugh Dickins
2015-02-11 9:58 ` Vlastimil Babka
2015-02-12 7:10 ` Joonsoo Kim
2015-02-11 21:09 ` Andrew Morton
2015-02-12 8:18 ` Vlastimil Babka
2015-02-12 15:12 ` Rik van Riel [this message]
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