From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751454AbdB0Q0E (ORCPT ); Mon, 27 Feb 2017 11:26:04 -0500 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:60861 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751039AbdB0Q0C (ORCPT ); Mon, 27 Feb 2017 11:26:02 -0500 Date: Mon, 27 Feb 2017 08:10:24 -0800 From: Shaohua Li To: Michal Hocko CC: , , , , , , , , Subject: Re: [PATCH V5 2/6] mm: don't assume anonymous pages have SwapBacked flag Message-ID: <20170227161022.GA62304@shli-mbp.local> References: <3945232c0df3dd6c4ef001976f35a95f18dcb407.1487965799.git.shli@fb.com> <20170227143534.GE26504@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20170227143534.GE26504@dhcp22.suse.cz> User-Agent: Mutt/1.6.1 (2016-04-27) X-Originating-IP: [2620:10d:c090:180::a4d] X-ClientProxiedBy: CO2PR05CA0070.namprd05.prod.outlook.com (10.166.88.166) To BN6PR15MB1635.namprd15.prod.outlook.com (10.175.131.9) X-MS-Office365-Filtering-Correlation-Id: 74f8e325-48b6-45e6-cf7e-08d45f2b2d09 X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:(22001);SRVR:BN6PR15MB1635; 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MADV_FREE pages are anonymous pages but we are > > going to add them to LRU_INACTIVE_FILE list and clear SwapBacked flag > > for them. The assumption doesn't hold any more, so fix them. > > > > Cc: Michal Hocko > > Cc: Minchan Kim > > Cc: Hugh Dickins > > Cc: Rik van Riel > > Cc: Mel Gorman > > Cc: Andrew Morton > > Acked-by: Johannes Weiner > > Signed-off-by: Shaohua Li > > Looks good to me. > [...] > > index 96eb85c..c621088 100644 > > --- a/mm/rmap.c > > +++ b/mm/rmap.c > > @@ -1416,7 +1416,8 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, > > * Store the swap location in the pte. > > * See handle_pte_fault() ... > > */ > > - VM_BUG_ON_PAGE(!PageSwapCache(page), page); > > + VM_BUG_ON_PAGE(!PageSwapCache(page) && PageSwapBacked(page), > > + page); > > just this part makes me scratch my head. I really do not understand what > kind of problem it tries to prevent from, maybe I am missing something > obvoious... Just check a page which isn't lazyfree but wrongly enters here without swap entry. Or maybe you suggest we delete this statement? Thanks, Shaohua