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From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
To: Rafael Aquini <aquini@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: [QUESTION] balloon page isolation needs LRU lock?
Date: Fri, 6 Dec 2013 17:53:31 +0900	[thread overview]
Message-ID: <20131206085331.GA24706@lge.com> (raw)

Hello, Rafael.

I looked at some compaction code and found that some oddity about
balloon compaction. In isolate_migratepages_range(), if we meet
!PageLRU(), we check whether this page is for balloon compaction.
In this case, code needs locked. Is the lock really needed? I can't find
any relationship between balloon compaction and LRU lock.

Second question is that in above case if we don't hold a lock, we
skip this page. I guess that if we meet balloon page repeatedly, there
is no change to run isolation. Am I missing?

Please let me know what I am missing.

Thanks in advance.

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WARNING: multiple messages have this Message-ID (diff)
From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
To: Rafael Aquini <aquini@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: [QUESTION] balloon page isolation needs LRU lock?
Date: Fri, 6 Dec 2013 17:53:31 +0900	[thread overview]
Message-ID: <20131206085331.GA24706@lge.com> (raw)

Hello, Rafael.

I looked at some compaction code and found that some oddity about
balloon compaction. In isolate_migratepages_range(), if we meet
!PageLRU(), we check whether this page is for balloon compaction.
In this case, code needs locked. Is the lock really needed? I can't find
any relationship between balloon compaction and LRU lock.

Second question is that in above case if we don't hold a lock, we
skip this page. I guess that if we meet balloon page repeatedly, there
is no change to run isolation. Am I missing?

Please let me know what I am missing.

Thanks in advance.

             reply	other threads:[~2013-12-06  8:50 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-12-06  8:53 Joonsoo Kim [this message]
2013-12-06  8:53 ` [QUESTION] balloon page isolation needs LRU lock? Joonsoo Kim
2013-12-06 12:21 ` Rafael Aquini
2013-12-06 12:21   ` Rafael Aquini
2013-12-09  8:47   ` Joonsoo Kim
2013-12-09  8:47     ` Joonsoo Kim

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