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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 DABC5C10F11 for ; Wed, 24 Apr 2019 15:16:33 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 25898218D3 for ; Wed, 24 Apr 2019 15:16:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 25898218D3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.ibm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 44q3nC16V6zDqSZ for ; Thu, 25 Apr 2019 01:16:31 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=linux.ibm.com (client-ip=148.163.156.1; helo=mx0a-001b2d01.pphosted.com; envelope-from=ldufour@linux.ibm.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=linux.ibm.com Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 44q3N21TfyzDqGY for ; Thu, 25 Apr 2019 00:58:10 +1000 (AEST) Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x3OEsTHu123349 for ; Wed, 24 Apr 2019 10:58:08 -0400 Received: from e06smtp04.uk.ibm.com (e06smtp04.uk.ibm.com [195.75.94.100]) by mx0a-001b2d01.pphosted.com with ESMTP id 2s2s1puy3y-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Wed, 24 Apr 2019 10:58:07 -0400 Received: from localhost by e06smtp04.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Wed, 24 Apr 2019 15:57:55 +0100 Received: from d06av26.portsmouth.uk.ibm.com (d06av26.portsmouth.uk.ibm.com [9.149.105.62]) by b06cxnps3075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x3OEvrA663176882 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 24 Apr 2019 14:57:53 GMT Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 6642AAE04D; Wed, 24 Apr 2019 14:57:53 +0000 (GMT) Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 93EFBAE051; Wed, 24 Apr 2019 14:57:50 +0000 (GMT) Received: from [9.145.176.48] (unknown [9.145.176.48]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 24 Apr 2019 14:57:50 +0000 (GMT) Subject: Re: [PATCH v12 23/31] mm: don't do swap readahead during speculative page fault To: Jerome Glisse References: <20190416134522.17540-1-ldufour@linux.ibm.com> <20190416134522.17540-24-ldufour@linux.ibm.com> <20190422213611.GN14666@redhat.com> From: Laurent Dufour Date: Wed, 24 Apr 2019 16:57:50 +0200 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190422213611.GN14666@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 19042414-0016-0000-0000-000002732720 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19042414-0017-0000-0000-000032CF99CC Message-Id: <42ba3103-cbac-199f-e6f1-0fbc12aaccc8@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2019-04-24_09:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904240116 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: jack@suse.cz, sergey.senozhatsky.work@gmail.com, peterz@infradead.org, Will Deacon , mhocko@kernel.org, linux-mm@kvack.org, paulus@samba.org, Punit Agrawal , hpa@zytor.com, Michel Lespinasse , Alexei Starovoitov , Andrea Arcangeli , ak@linux.intel.com, Minchan Kim , aneesh.kumar@linux.ibm.com, x86@kernel.org, Matthew Wilcox , Daniel Jordan , Ingo Molnar , David Rientjes , paulmck@linux.vnet.ibm.com, Haiyan Song , npiggin@gmail.com, sj38.park@gmail.com, dave@stgolabs.net, kemi.wang@intel.com, kirill@shutemov.name, Thomas Gleixner , zhong jiang , Ganesh Mahendran , Yang Shi , Mike Rapoport , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, Sergey Senozhatsky , Vinayak Menon , vinayak menon , akpm@linux-foundation.org, Tim Chen , haren@linux.vnet.ibm.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Le 22/04/2019 à 23:36, Jerome Glisse a écrit : > On Tue, Apr 16, 2019 at 03:45:14PM +0200, Laurent Dufour wrote: >> Vinayak Menon faced a panic because one thread was page faulting a page in >> swap, while another one was mprotecting a part of the VMA leading to a VMA >> split. >> This raise a panic in swap_vma_readahead() because the VMA's boundaries >> were not more matching the faulting address. >> >> To avoid this, if the page is not found in the swap, the speculative page >> fault is aborted to retry a regular page fault. >> >> Reported-by: Vinayak Menon >> Signed-off-by: Laurent Dufour > > Reviewed-by: Jérôme Glisse > > Note that you should also skip non swap entry in do_swap_page() when doing > speculative page fault at very least you need to is_device_private_entry() > case. > > But this should either be part of patch 22 or another patch to fix swap > case. Thanks Jérôme, Yes I missed that, I guess the best option would be to abort on non swap entry. I'll add that in the patch 22. >> --- >> mm/memory.c | 11 +++++++++++ >> 1 file changed, 11 insertions(+) >> >> diff --git a/mm/memory.c b/mm/memory.c >> index 6e6bf61c0e5c..1991da97e2db 100644 >> --- a/mm/memory.c >> +++ b/mm/memory.c >> @@ -2900,6 +2900,17 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) >> lru_cache_add_anon(page); >> swap_readpage(page, true); >> } >> + } else if (vmf->flags & FAULT_FLAG_SPECULATIVE) { >> + /* >> + * Don't try readahead during a speculative page fault >> + * as the VMA's boundaries may change in our back. >> + * If the page is not in the swap cache and synchronous >> + * read is disabled, fall back to the regular page >> + * fault mechanism. >> + */ >> + delayacct_clear_flag(DELAYACCT_PF_SWAPIN); >> + ret = VM_FAULT_RETRY; >> + goto out; >> } else { >> page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, >> vmf); >> -- >> 2.21.0 >> >