From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 02BD9C433F5 for ; Sun, 2 Sep 2018 06:59:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 716FC20835 for ; Sun, 2 Sep 2018 06:59:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Zf6Caumx" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 716FC20835 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726135AbeIBLNs (ORCPT ); Sun, 2 Sep 2018 07:13:48 -0400 Received: from mail-pl1-f195.google.com ([209.85.214.195]:33456 "EHLO mail-pl1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725904AbeIBLNs (ORCPT ); Sun, 2 Sep 2018 07:13:48 -0400 Received: by mail-pl1-f195.google.com with SMTP id b92-v6so2213359plb.0; Sat, 01 Sep 2018 23:59:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to :user-agent; bh=BfDrHFhMMGp4YbOjXL4+FJ5Lbow2qPk9kolnnl3aPx8=; b=Zf6Caumxx4BidYsuyoYi5jfwQ9B2yyf3LRfwMeiSTOyf4tVrgmiTBObPcI/O6BlDwP 0Q+BxGXIE7wTjGJMA8aJ/4FCIHLxTedCleflcPOwx3gLOCVuPHntUNFOTOeh54jDts2q PIyfLi8ld+cqgB6LPyBlDd6MNAqsJ07Z12tgs61kw1Tiru3ZHeLuGreSs5fCTwLKvDbX EJta4kvaE1tCaVKjNmEg529YIUt71xYd8PUyhep6E3D+OTxPU2GLPIjzrWs4AzaKq2t5 uaC8lu7Mv8ipRuGzbg4iCaqKUzRMSn1fHeguie9l3IHPSQqxA+3fk94ZihLoWauZI9A0 t7sw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to:user-agent; bh=BfDrHFhMMGp4YbOjXL4+FJ5Lbow2qPk9kolnnl3aPx8=; b=cTis0Ajx7aeFOgtya/s9MjHwvOPZr4djWWKBrs/kp8qnOyF29f5zc8T0Yyo0X1QYhG H/8rm3FBg/SSR+idNy7r5MNmuVeueJB1VfGhOZZTSpKdEbGJCvPlfj06DO0UuxsOo6UF P2/xJnOdfUYp/7fcdcPojF53idYa3qgTGPlDe1LclN8m7pAj6MotHKySVpd0woOQmO5Y MHW5EUIvJtpTvg/ZY7vGUzlahN8yqAWckHdDTePR5Vq5sLucRZjHl7DeV1CiQkBrl4+N /TBFgdFsDs7Rvq08KjX/Y/luMZr306uGAAUGPuzE62/YLWVxUXcap+qHNHy9Sni5IoWd C5HQ== X-Gm-Message-State: APzg51Cn7NzOpfZNFDbFVAaCLDGrqBxBn4ZT9+7FrTl941OE6WnqJzSF b7CuelJvwcYqz6rxL0QSyjk= X-Google-Smtp-Source: ANB0VdbwZTyKsJj3QOo8IgqFWlGvoOHv58c8we4xV3yiIEwT/15dExm+445Lh8OGeTa1kDEho/hDzQ== X-Received: by 2002:a17:902:246a:: with SMTP id m39-v6mr22531386plg.57.1535871543808; Sat, 01 Sep 2018 23:59:03 -0700 (PDT) Received: from localhost (14-202-194-140.static.tpgi.com.au. [14.202.194.140]) by smtp.gmail.com with ESMTPSA id d81-v6sm19890941pfj.122.2018.09.01.23.59.02 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Sat, 01 Sep 2018 23:59:03 -0700 (PDT) Date: Sun, 2 Sep 2018 16:58:59 +1000 From: Balbir Singh To: Jerome Glisse Cc: linux-mm@kvack.org, Andrew Morton , linux-kernel@vger.kernel.org, Ralph Campbell , "Kirill A . Shutemov" , stable@vger.kernel.org Subject: Re: [PATCH 3/7] mm/rmap: map_pte() was not handling private ZONE_DEVICE page properly v2 Message-ID: <20180902065859.GE28695@350D> References: <20180824192549.30844-3-jglisse@redhat.com> <20180830144156.7226-1-jglisse@redhat.com> <20180831092724.GD28695@350D> <20180831161935.GB4111@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20180831161935.GB4111@redhat.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 31, 2018 at 12:19:35PM -0400, Jerome Glisse wrote: > On Fri, Aug 31, 2018 at 07:27:24PM +1000, Balbir Singh wrote: > > On Thu, Aug 30, 2018 at 10:41:56AM -0400, jglisse@redhat.com wrote: > > > From: Ralph Campbell > > > > > > Private ZONE_DEVICE pages use a special pte entry and thus are not > > > present. Properly handle this case in map_pte(), it is already handled > > > in check_pte(), the map_pte() part was lost in some rebase most probably. > > > > > > Without this patch the slow migration path can not migrate back private > > > ZONE_DEVICE memory to regular memory. This was found after stress > > > testing migration back to system memory. This ultimatly can lead the > > > CPU to an infinite page fault loop on the special swap entry. > > > > > > Changes since v1: > > > - properly lock pte directory in map_pte() > > > > > > Signed-off-by: Ralph Campbell > > > Signed-off-by: Jérôme Glisse > > > Cc: Andrew Morton > > > Cc: Kirill A. Shutemov > > > Cc: Balbir Singh > > > Cc: stable@vger.kernel.org > > > --- > > > mm/page_vma_mapped.c | 9 ++++++++- > > > 1 file changed, 8 insertions(+), 1 deletion(-) > > > > > > diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c > > > index ae3c2a35d61b..bd67e23dce33 100644 > > > --- a/mm/page_vma_mapped.c > > > +++ b/mm/page_vma_mapped.c > > > @@ -21,7 +21,14 @@ static bool map_pte(struct page_vma_mapped_walk *pvmw) > > > if (!is_swap_pte(*pvmw->pte)) > > > return false; > > > } else { > > > - if (!pte_present(*pvmw->pte)) > > > + if (is_swap_pte(*pvmw->pte)) { > > > + swp_entry_t entry; > > > + > > > + /* Handle un-addressable ZONE_DEVICE memory */ > > > + entry = pte_to_swp_entry(*pvmw->pte); > > > + if (!is_device_private_entry(entry)) > > > + return false; > > > > OK, so we skip this pte from unmap since it's already unmapped? This prevents > > try_to_unmap from unmapping it and it gets restored with MIGRATE_PFN_MIGRATE > > flag cleared? > > > > Sounds like the right thing, if I understand it correctly > > Well not exactly we do not skip it, we replace it with a migration I think I missed the !is_device_private_entry and missed the ! part, so that seems reasonable Reviewed-by: Balbir Singh