Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1756954AbdCHGmV (ORCPT <rfc822;w@1wt.eu>);
        Wed, 8 Mar 2017 01:42:21 -0500
Received: from LGEAMRELO13.lge.com ([156.147.23.53]:55970 "EHLO
        lgeamrelo13.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1756752AbdCHGl4 (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Wed, 8 Mar 2017 01:41:56 -0500
X-Original-SENDERIP: 156.147.1.151
X-Original-MAILFROM: minchan@kernel.org
X-Original-SENDERIP: 165.244.249.26
X-Original-MAILFROM: minchan@kernel.org
X-Original-SENDERIP: 10.177.223.161
X-Original-MAILFROM: minchan@kernel.org
Date: Wed, 8 Mar 2017 15:41:47 +0900
From: Minchan Kim <minchan@kernel.org>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
CC: Andrew Morton <akpm@linux-foundation.org>, <kernel-team@lge.com>,
        <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
        Johannes Weiner <hannes@cmpxchg.org>, Michal Hocko <mhocko@suse.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [RFC 05/11] mm: make the try_to_munlock void function
Message-ID: <20170308064147.GG11206@bbox>
References: <1488436765-32350-1-git-send-email-minchan@kernel.org>
 <1488436765-32350-6-git-send-email-minchan@kernel.org>
 <20170307151747.GA2940@node.shutemov.name>
MIME-Version: 1.0
In-Reply-To: <20170307151747.GA2940@node.shutemov.name>
User-Agent: Mutt/1.5.24 (2015-08-30)
X-MIMETrack: Itemize by SMTP Server on LGEKRMHUB08/LGE/LG Group(Release 8.5.3FP6|November
 21, 2013) at 2017/03/08 15:41:47,
        Serialize by Router on LGEKRMHUB08/LGE/LG Group(Release 8.5.3FP6|November
 21, 2013) at 2017/03/08 15:41:47,
        Serialize complete at 2017/03/08 15:41:47
Content-Type: text/plain; charset="us-ascii"
Content-Disposition: inline
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 1302
Lines: 40

On Tue, Mar 07, 2017 at 06:17:47PM +0300, Kirill A. Shutemov wrote:
> On Thu, Mar 02, 2017 at 03:39:19PM +0900, Minchan Kim wrote:
> > try_to_munlock returns SWAP_MLOCK if the one of VMAs mapped
> > the page has VM_LOCKED flag. In that time, VM set PG_mlocked to
> > the page if the page is not pte-mapped THP which cannot be
> > mlocked, either.
> > 
> > With that, __munlock_isolated_page can use PageMlocked to check
> > whether try_to_munlock is successful or not without relying on
> > try_to_munlock's retval. It helps to make ttu/ttuo simple with
> > upcoming patches.
> 
> I *think* you're correct, but it took time to wrap my head around.
> We basically rely on try_to_munlock() never caller for PTE-mapped THP.
> And we don't at the moment.
> 
> It worth adding something like
> 
> 	VM_BUG_ON_PAGE(PageCompound(page) && PageDoubleMap(page), page);
> 
> into try_to_munlock().

Agree.

> 
> Otherwise looks good to me.
> 
> Will free adding my Acked-by once this nit is addressed.

Thanks for the review this part, Kirill!

> 
> -- 
>  Kirill A. Shutemov
> 
> --
> 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/ .
> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>