From: Johannes Weiner <jweiner@redhat.com>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Ying Han <yinghan@google.com>,
Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>,
Balbir Singh <bsingharora@gmail.com>,
Michal Hocko <mhocko@suse.cz>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [patch] mm: memcg: close race between charge and putback
Date: Thu, 8 Sep 2011 10:54:04 +0200 [thread overview]
Message-ID: <20110908085404.GA1316@redhat.com> (raw)
In-Reply-To: <20110908173042.4a6f8ac0.kamezawa.hiroyu@jp.fujitsu.com>
On Thu, Sep 08, 2011 at 05:30:42PM +0900, KAMEZAWA Hiroyuki wrote:
> On Thu, 8 Sep 2011 09:40:22 +0200
> Johannes Weiner <jweiner@redhat.com> wrote:
>
> > There is a potential race between a thread charging a page and another
> > thread putting it back to the LRU list:
> >
> > charge: putback:
> > SetPageCgroupUsed SetPageLRU
> > PageLRU && add to memcg LRU PageCgroupUsed && add to memcg LRU
> >
>
> I assumed that all pages are charged before added to LRU.
> (i.e. event happens in charge->lru_lock->putback order.)
>
> But hmm, this assumption may be bad for maintainance.
> Do you find a code which adds pages to LRU before charge ?
>
> Hmm, if there are codes which recharge the page to other memcg,
> it will cause bug and my assumption may be harmful.
Swap slots are read optimistically into swapcache and put to the LRU,
then charged upon fault. Fuse apparently recharges uncharged LRU
pages. That's why we have the lrucare stuff in the first place, no?
Or did I misunderstand your question?
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2011-09-08 8:54 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-08 7:40 [patch] mm: memcg: close race between charge and putback Johannes Weiner
2011-09-08 8:30 ` KAMEZAWA Hiroyuki
2011-09-08 8:54 ` Johannes Weiner [this message]
2011-09-08 9:19 ` KAMEZAWA Hiroyuki
2011-09-08 9:33 ` Johannes Weiner
2011-09-08 9:42 ` KAMEZAWA Hiroyuki
2011-09-08 9:53 ` Johannes Weiner
2011-09-09 0:28 ` KAMEZAWA Hiroyuki
2011-09-09 6:28 ` Johannes Weiner
2011-09-09 6:48 ` KAMEZAWA Hiroyuki
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20110908085404.GA1316@redhat.com \
--to=jweiner@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=bsingharora@gmail.com \
--cc=kamezawa.hiroyu@jp.fujitsu.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@suse.cz \
--cc=nishimura@mxp.nes.nec.co.jp \
--cc=yinghan@google.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).