Re: [PATCH] memcg: fix stale swap cache leak v5

From: Balbir Singh
Date: Thu Apr 30 2009 - 05:43:19 EST


* KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> [2009-04-30 18:04:26]:

> On Thu, 30 Apr 2009 16:35:39 +0900
> KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
>
> > On Thu, 30 Apr 2009 16:16:27 +0900
> > KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
> >
> > > This is v5 but all codes are rewritten.
> > >
> > > After this patch, when memcg is used,
> > > 1. page's swapcount is checked after I/O (without locks). If the page is
> > > stale swap cache, freeing routine will be scheduled.
> > > 2. vmscan.c calls try_to_free_swap() when __remove_mapping() fails.
> > >
> > > Works well for me. no extra resources and no races.
> > >
> > > Because my office will be closed until May/7, I'll not be able to make a
> > > response. Posting this for showing what I think of now.
> > >
> > I found a hole immediately after posted this...sorry. plz ignore this patch/
> > see you again in the next month.
> >
> I'm now wondering to disable "swapin readahed" completely when memcg is used...
> Then, half of the problems will go away immediately.
> And it's not so bad to try to free swapcache if swap writeback ends. Then, another
> half will go away...
>

Could you clarify? Will memcg not account for swapin readahead pages?


--
Balbir
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