From: Fengguang Wu <fengguang.wu@intel.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Jan Kara <jack@suse.cz>, Greg Thelen <gthelen@google.com>,
Ying Han <yinghan@google.com>,
"hannes@cmpxchg.org" <hannes@cmpxchg.org>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Rik van Riel <riel@redhat.com>, Mel Gorman <mgorman@suse.de>,
Minchan Kim <minchan.kim@gmail.com>,
Linux Memory Management List <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 5/9] writeback: introduce the pageout work
Date: Tue, 6 Mar 2012 21:40:49 -0800 [thread overview]
Message-ID: <20120307054049.GA12256@localhost> (raw)
In-Reply-To: <20120306163742.b71bf57b.akpm@linux-foundation.org>
On Tue, Mar 06, 2012 at 04:37:42PM -0800, Andrew Morton wrote:
> On Sat, 3 Mar 2012 21:25:55 +0800
> Fengguang Wu <fengguang.wu@intel.com> wrote:
>
> > > > get_page() looks the perfect solution to verify if the struct inode
> > > > pointer (w/o igrab) is still live and valid.
> > > >
> > > > [...upon rethinking...] Oh but still we need to lock some page to pin
> > > > the inode during the writeout. Then there is the dilemma: if the page
> > > > is locked, we effectively keep it from being written out...
> > >
> > > No, all you need to do is to structure the code so that after the page
> > > gets unlocked, the kernel thread does not touch the address_space. So
> > > the processing within the kthread is along the lines of
> > >
> > > writearound(locked_page)
> > > {
> > > write some pages preceding locked_page; /* touches address_space */
> >
> > It seems the above line will lead to ABBA deadlock.
> >
> > At least btrfs will lock a number of pages in lock_delalloc_pages().
>
> Well, this code locks multiple pages too. I forget what I did about
> that - probably trylock. Dirty pages aren't locked for very long.
Yeah, trylock will be OK. And if the filesystems all do trylocks when
writing out any extra pages they try to piggy back, the ABBA deadlock
can be avoided. That makes the get_page()+trylock_page() scheme feasible.
Thanks,
Fengguang
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next prev parent reply other threads:[~2012-03-07 5:45 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-28 14:00 [PATCH 0/9] [RFC] pageout work and dirty reclaim throttling Fengguang Wu
2012-02-28 14:00 ` [PATCH 1/9] memcg: add page_cgroup flags for dirty page tracking Fengguang Wu
2012-02-29 0:50 ` KAMEZAWA Hiroyuki
2012-03-04 1:29 ` Fengguang Wu
2012-02-28 14:00 ` [PATCH 2/9] memcg: add dirty page accounting infrastructure Fengguang Wu
2012-02-28 22:37 ` Andrew Morton
2012-02-29 0:27 ` Fengguang Wu
2012-02-28 14:00 ` [PATCH 3/9] memcg: add kernel calls for memcg dirty page stats Fengguang Wu
2012-02-29 1:10 ` KAMEZAWA Hiroyuki
2012-02-28 14:00 ` [PATCH 4/9] memcg: dirty page accounting support routines Fengguang Wu
2012-02-28 15:15 ` Fengguang Wu
2012-02-28 22:45 ` Andrew Morton
2012-02-29 1:15 ` KAMEZAWA Hiroyuki
2012-02-28 14:00 ` [PATCH 5/9] writeback: introduce the pageout work Fengguang Wu
2012-02-29 0:04 ` Andrew Morton
2012-02-29 2:31 ` Fengguang Wu
2012-02-29 13:28 ` Fengguang Wu
2012-03-01 11:04 ` Jan Kara
2012-03-01 11:41 ` Fengguang Wu
2012-03-01 16:50 ` Jan Kara
2012-03-01 19:46 ` Andrew Morton
2012-03-03 13:25 ` Fengguang Wu
2012-03-07 0:37 ` Andrew Morton
2012-03-07 5:40 ` Fengguang Wu [this message]
2012-03-01 19:42 ` Andrew Morton
2012-03-01 21:15 ` Jan Kara
2012-03-01 21:22 ` Andrew Morton
2012-03-01 12:36 ` Fengguang Wu
2012-03-01 16:38 ` Jan Kara
2012-03-02 4:48 ` Fengguang Wu
2012-03-02 9:59 ` Jan Kara
2012-03-02 10:39 ` Fengguang Wu
2012-03-02 19:57 ` Andrew Morton
2012-03-03 13:55 ` Fengguang Wu
2012-03-03 14:27 ` Fengguang Wu
2012-03-04 11:13 ` Fengguang Wu
2012-03-07 15:48 ` Artem Bityutskiy
2012-03-09 7:31 ` Fengguang Wu
2012-03-09 9:51 ` Jan Kara
2012-03-09 10:24 ` Artem Bityutskiy
2012-03-09 16:10 ` Artem Bityutskiy
2012-03-09 21:11 ` Jan Kara
2012-03-12 12:36 ` Artem Bityutskiy
2012-03-12 14:02 ` Jan Kara
2012-03-12 14:21 ` Artem Bityutskiy
2012-03-09 10:15 ` Jan Kara
2012-03-09 15:10 ` Fengguang Wu
2012-02-29 13:51 ` [PATCH v2 " Fengguang Wu
2012-03-01 13:35 ` Fengguang Wu
2012-03-02 6:22 ` [PATCH v3 " Fengguang Wu
2012-02-28 14:00 ` [PATCH 6/9] vmscan: dirty reclaim throttling Fengguang Wu
2012-02-28 14:00 ` [PATCH 7/9] mm: pass __GFP_WRITE to memcg charge and reclaim routines Fengguang Wu
2012-02-28 14:00 ` [PATCH 8/9] mm: dont set __GFP_WRITE on ramfs/sysfs writes Fengguang Wu
2012-03-01 10:13 ` Johannes Weiner
2012-03-01 10:30 ` Fengguang Wu
2012-02-28 14:00 ` [PATCH 9/9] mm: debug vmscan waits Fengguang Wu
2012-03-02 6:59 ` [RFC PATCH] mm: don't treat anonymous pages as dirtyable pages Fengguang Wu
2012-03-02 7:18 ` Fengguang Wu
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