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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Yang Shi <shy828301@gmail.com>
Cc: Linux MM <linux-mm@kvack.org>, Thomas Gleixner <tglx@linutronix.de>
Subject: Re: Memory compaction and mlockall()
Date: Thu, 11 Jul 2019 11:43:24 +0200	[thread overview]
Message-ID: <20190711094324.ninnmarx5r3amz4p@linutronix.de> (raw)
In-Reply-To: <CAHbLzkpME1oT2=-TNPm9S_iZ2nkGsY6AXo7iVgDUhg8WysDpZw@mail.gmail.com>

On 2019-07-10 11:21:19 [-0700], Yang Shi wrote:
> 
> compaction should not isolate unevictable pages unless you have
> /proc/sys/vm/compact_unevictable_allowed set.

Thank you. This is enabled by default. The documentation for this says
| … compaction is allowed to examine the unevictable lru (mlocked pages) for
| pages to compact.…

so it is actually clear once you know where to look.
If I read this correct, the default behavior was to ignore mlock()ed
pages for compaction then commit
  5bbe3547aa3ba ("mm: allow compaction of unevictable pages")

came along in v4.1-rc1 and changed that behaviour. Is it too late to
flip it back?

Sebastian


  reply	other threads:[~2019-07-11  9:43 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-10 14:41 Sebastian Andrzej Siewior
2019-07-10 16:20 ` Dave Hansen
2019-07-10 16:45   ` Sebastian Andrzej Siewior
2019-07-10 17:02     ` Dave Hansen
2019-07-10 18:21 ` Yang Shi
2019-07-11  9:43   ` Sebastian Andrzej Siewior [this message]
2019-07-11 16:23     ` Yang Shi
2019-08-12 14:59     ` Vlastimil Babka
2019-08-12 15:54       ` Sebastian Andrzej Siewior
2019-08-13  8:23         ` Vlastimil Babka

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