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Date: Sun, 27 Jan 2013 19:35:31 -0800 (PST)
From: Hugh Dickins <hughd@google.com>
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To: Simon Jeons <simon.jeons@gmail.com>
cc: Andrew Morton <akpm@linux-foundation.org>,
        Petr Holasek <pholasek@redhat.com>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Izik Eidus <izik.eidus@ravellosystems.com>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 5/11] ksm: get_ksm_page locked
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On Sun, 27 Jan 2013, Simon Jeons wrote:
> On Sun, 2013-01-27 at 14:08 -0800, Hugh Dickins wrote:
> > On Sat, 26 Jan 2013, Simon Jeons wrote:
> > > 
> > > Why the parameter lock passed from stable_tree_search/insert is true,
> > > but remove_rmap_item_from_tree is false?
> > 
> > The other way round?  remove_rmap_item_from_tree needs the page locked,
> > because it's about to modify the list: that's secured (e.g. against
> > concurrent KSM page reclaim) by the page lock.
> 
> How can KSM page reclaim path call remove_rmap_item_from_tree? I have
> already track every callsites but can't find it.

It doesn't.  Please read what I said above again.

> BTW, I'm curious about
> KSM page reclaim, it seems that there're no special handle in vmscan.c
> for KSM page reclaim, is it will be reclaimed similiar with normal
> page? 

Look for PageKsm in mm/rmap.c.