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From: Mel Gorman <mgorman@techsingularity.net>
To: "Huang, Ying" <ying.huang@intel.com>
Cc: Jan Kara <jack@suse.cz>, Mel Gorman <mgorman@suse.de>,
	Minchan Kim <minchan@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Hugh Dickins <hughd@google.com>,
	"Paul E . McKenney" <paulmck@linux.vnet.ibm.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Tim Chen <tim.c.chen@linux.intel.com>, Shaohua Li <shli@fb.com>,
	J???r???me Glisse <jglisse@redhat.com>,
	Michal Hocko <mhocko@suse.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	David Rientjes <rientjes@google.com>,
	Rik van Riel <riel@redhat.com>, Dave Jiang <dave.jiang@intel.com>,
	Aaron Lu <aaron.lu@intel.com>
Subject: Re: [PATCH -V4 -mm] mm, swap: Fix race between swapoff and some swap operations
Date: Thu, 4 Jan 2018 10:21:14 +0000	[thread overview]
Message-ID: <20180104102114.l45sjluuzdgpcfd7@techsingularity.net> (raw)
In-Reply-To: <87lgheh173.fsf@yhuang-dev.intel.com>

On Thu, Jan 04, 2018 at 09:17:36AM +0800, Huang, Ying wrote:
> > Maybe, but in this particular case, I would prefer to go with something
> > more conventional unless there is strong evidence that it's an improvement
> > (which I doubt in this case given the cost of migration overall and the
> > corner case of migrating a dirty page).
> 
> So you like page_lock() more than RCU? 

In this instance, yes.

> Is there any problem of RCU?
> The object to be protected isn't clear?
> 

It's not clear what object is being protected or how it's protected and
it's not the usual means a mapping is pinned. Furthermore, in the event
a page is being truncated, we really do not want to bother doing any
migration work for compaction purposes as it's a waste.

-- 
Mel Gorman
SUSE Labs

      reply	other threads:[~2018-01-04 10:21 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-12-20  1:26 [PATCH -V4 -mm] mm, swap: Fix race between swapoff and some swap operations Huang, Ying
2017-12-21  2:16 ` Minchan Kim
     [not found]   ` <871sjopllj.fsf@yhuang-dev.intel.com>
2017-12-21 23:58     ` Minchan Kim
2017-12-22 14:14       ` Huang, Ying
2017-12-22 16:14         ` Paul E. McKenney
2017-12-25  1:28           ` Huang, Ying
2017-12-23  1:36         ` Minchan Kim
2017-12-26  5:33           ` Huang, Ying
2018-01-02 10:21           ` Mel Gorman
2018-01-02 11:29             ` Jan Kara
2018-01-02 13:29               ` Mel Gorman
2018-01-03  0:42                 ` Huang, Ying
2018-01-03  9:54                   ` Mel Gorman
2018-01-04  1:17                     ` Huang, Ying
2018-01-04 10:21                       ` Mel Gorman [this message]

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