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=-2.3 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 C1B5BC433F5 for ; Thu, 30 Aug 2018 14:05:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6C5DD2073D for ; Thu, 30 Aug 2018 14:05:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="qSYZczYd" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6C5DD2073D 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 S1729158AbeH3SIB (ORCPT ); Thu, 30 Aug 2018 14:08:01 -0400 Received: from mail-pf1-f196.google.com ([209.85.210.196]:32805 "EHLO mail-pf1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728962AbeH3SIA (ORCPT ); Thu, 30 Aug 2018 14:08:00 -0400 Received: by mail-pf1-f196.google.com with SMTP id d4-v6so3951722pfn.0; Thu, 30 Aug 2018 07:05:43 -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=fptreHptAAOohSZmFgomIuC4PZXLD7LeMRAOT0hZG/4=; b=qSYZczYdDY6y6fq9E7SBzY1NbQeTzxoVJOnCVCWf7RE0KIh4mEx+K8L8eZ7lxDBojA KyjrBVyvVi8M/JHsPyKcUKKSdzVOwniolCxt0T+fHFAbB1oBfGMSAyKf3bkhZoHQ6lqy Pu7Kr/YptYBynlTQ2WiAY8e3y5Nj/SdCo88qLAg/WrXg4j1U76ign7TDyMhvMNHuQHIf GYEZFvHTk+HOUpZSWbwMIJKAstxCJIs7Tcr2ZyjdOARHFiEePOU0p3V+KAmWmxgbF0Zq MtbnUidplDh2c6YhIqhAqHttiXUTePniGtcR79UslkY77bvdFW4t+Uciz0pIdNNzaROF Ec/g== 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=fptreHptAAOohSZmFgomIuC4PZXLD7LeMRAOT0hZG/4=; b=sTU5Okp298Ujm39BzbqiqXjUTEC6AC4TWTnv80/1ETnG05pmb8lwi9v93rms+iBqd5 xrzhnfm4EP7MPgJQz+fG9al8hjpXT2tn8507+1jTVGrgZaL8sKYNDARVR+I2xJqTq51p socI6Ls5v9urMdh4pUUkCHAhCshIWGfkq1vsy/whOBoF2Lb+GTZIyDYGtRF6kkhk3DfB x/Ql0wiSACWIqumxti+N4MVt4tA8spFSN46gCsvXHCFS1f4Yq3/bQqLZjp0+OxUdvBD7 MmB0EqKhBS/O6jDvTCyeDczqrdMfB7vD5Jw2M42JAq92fo/ZiZJDNY+hfKvI9Fo0COVL mOpA== X-Gm-Message-State: APzg51DHByjreSeZptTNzwmaT7EqcyBnx4Cd7SJt+yYy0GUoLur1LL9m SCd7L+W2vcN/5rgMiV7ENvs= X-Google-Smtp-Source: ANB0VdZthBDSk1b5hbz/ylW0QOLM+Xm12I1bUosVDw+fB8RNkqUrK0qIqiQJ8a4xnywKrrIPHz+1sg== X-Received: by 2002:a63:dc17:: with SMTP id s23-v6mr10058330pgg.40.1535637942461; Thu, 30 Aug 2018 07:05:42 -0700 (PDT) Received: from localhost (14-202-194-140.static.tpgi.com.au. [14.202.194.140]) by smtp.gmail.com with ESMTPSA id i20-v6sm9975345pfj.82.2018.08.30.07.05.41 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 30 Aug 2018 07:05:41 -0700 (PDT) Date: Fri, 31 Aug 2018 00:05:38 +1000 From: Balbir Singh To: jglisse@redhat.com Cc: linux-mm@kvack.org, Andrew Morton , linux-kernel@vger.kernel.org, Ralph Campbell , "Kirill A . Shutemov" , stable@vger.kernel.org Subject: Re: [PATCH 2/7] mm/rmap: map_pte() was not handling private ZONE_DEVICE page properly Message-ID: <20180830140538.GA28695@350D> References: <20180824192549.30844-1-jglisse@redhat.com> <20180824192549.30844-3-jglisse@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20180824192549.30844-3-jglisse@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 24, 2018 at 03:25:44PM -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. > > Signed-off-by: Ralph Campbell > Signed-off-by: Jérôme Glisse > Cc: Andrew Morton > Cc: Kirill A. Shutemov > Cc: stable@vger.kernel.org > --- > mm/page_vma_mapped.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c > index ae3c2a35d61b..1cf5b9bfb559 100644 > --- a/mm/page_vma_mapped.c > +++ b/mm/page_vma_mapped.c > @@ -21,6 +21,15 @@ static bool map_pte(struct page_vma_mapped_walk *pvmw) > if (!is_swap_pte(*pvmw->pte)) > return false; > } else { > + 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 true; > + } > + This happens just for !PVMW_SYNC && PVMW_MIGRATION? I presume this is triggered via the remove_migration_pte() code path? Doesn't returning true here imply that we've taken the ptl lock for the pvmw? Balbir