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From: Andrew Morton <akpm@linux-foundation.org>
To: Mel Gorman <mgorman@suse.de>
Cc: Jan Kara <jack@suse.cz>,
	linux-mm@kvack.org, mhocko@suse.cz, stable@vger.kernel.org
Subject: Re: [PATCH RFC] mm: migrate: Fix races of __find_get_block() and page migration
Date: Fri, 12 Jul 2019 14:21:11 -0700
Message-ID: <20190712142111.eac6322eea55f7e8f75b7b33@linux-foundation.org> (raw)
In-Reply-To: <20190712123935.GK13484@suse.de>

On Fri, 12 Jul 2019 13:39:35 +0100 Mel Gorman <mgorman@suse.de> wrote:

> > So although I still think that just failing the migration if we cannot
> > invalidate buffer heads is a safer choice, just extending the private_lock
> > protected section does not seem as bad as I was afraid.
> > 
> 
> That does not seem too bad and your revised patch looks functionally
> fine. I'd leave out the tracepoints though because a perf probe would have
> got roughly the same data and the tracepoint may be too specific to track
> another class of problem. Whether the tracepoint survives or not and
> with a changelog added;
> 
> Acked-by: Mel Gorman <mgorman@techsingularity.net>
> 
> Andrew, which version do you want to go with, the original version or
> this one that holds private_lock for slightly longer during migration?

The revised version looks much more appealing for a -stable backport. 
I expect any mild performance issues can be address in the usual
fashion.  My main concern is not to put a large performance regression
into mainline and stable kernels.  How confident are we that this is
(will be) sufficiently tested from that point of view?



  reply index

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-11 12:58 Jan Kara
2019-07-12  0:04 ` Andrew Morton
2019-07-12  8:04   ` Mel Gorman
2019-07-12  9:17   ` Jan Kara
2019-07-12 10:10     ` Mel Gorman
2019-07-12 11:20       ` Jan Kara
2019-07-12 12:39         ` Mel Gorman
2019-07-12 21:21           ` Andrew Morton [this message]
2019-07-14 21:20             ` Mel Gorman

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