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Date: Mon, 10 Mar 2014 22:01:58 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Dave Jones <davej@redhat.com>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>, linux-mm@kvack.org,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Sasha Levin <sasha.levin@oracle.com>,
        Cyrill Gorcunov <gorcunov@gmail.com>,
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        Wanpeng Li <liwanp@linux.vnet.ibm.com>, Bob Liu <bob.liu@oracle.com>,
        Konstantin Khlebnikov <koct9i@gmail.com>
Subject: Re: bad rss-counter message in 3.14rc5
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On Tue, 11 Mar 2014 00:51:09 -0400 Dave Jones <davej@redhat.com> wrote:

> On Mon, Mar 10, 2014 at 09:46:12PM -0700, Andrew Morton wrote:
>  > On Mon, 10 Mar 2014 20:13:40 -0700 Andrew Morton <akpm@linux-foundation.org> wrote:
>  > 
>  > > > Anyone ? I'm hitting this trace on an almost daily basis, which is a pain
>  > > > while trying to reproduce a different bug..
>  > > 
>  > > Damn, I thought we'd fixed that but it seems not.  Cc's added.
>  > > 
>  > > Guys, what stops the migration target page from coming unlocked in
>  > > parallel with zap_pte_range()'s call to migration_entry_to_page()?
>  > 
>  > page_table_lock, sort-of.  At least, transitions of is_migration_entry()
>  > and page_locked() happen under ptl.
>  > 
>  > I don't see any holes in regular migration.  Do you know if this is
>  > reproducible with CONFIG_NUMA_BALANCING=n or CONFIG_NUMA=n?
> 
> CONFIG_NUMA_BALANCING was n already btw, so I'll do a NUMA=n run.

There probably isn't much point unless trinity is using
sys_move_pages().  Is it?  If so it would be interesting to disable
trinity's move_pages calls and see if it still fails.

Grasping at straws here, trying to reduce the amount of code to look at :(