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=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,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 95F54C433B4 for ; Mon, 19 Apr 2021 02:15:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6E0F6610CE for ; Mon, 19 Apr 2021 02:15:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237255AbhDSCPq (ORCPT ); Sun, 18 Apr 2021 22:15:46 -0400 Received: from mga05.intel.com ([192.55.52.43]:49488 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233179AbhDSCPn (ORCPT ); Sun, 18 Apr 2021 22:15:43 -0400 IronPort-SDR: XrIkAxIUvo3Op8/Rkgqi5ngQkB1kVOPkh3OL7V6fl59yP884B1/n5/Jx63uwM5nL01moQexEHC u1ji6HvSZhng== X-IronPort-AV: E=McAfee;i="6200,9189,9958"; a="280580654" X-IronPort-AV: E=Sophos;i="5.82,232,1613462400"; d="scan'208";a="280580654" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Apr 2021 19:15:14 -0700 IronPort-SDR: iJjwYR+WlUCHdbwjvyCtNT+ukBMAkaTydHU70GJ1WrjiN6l+88DpV2LJgzaiQkjgeJ/vQ5RyFg FAqkOlPBbhfw== X-IronPort-AV: E=Sophos;i="5.82,232,1613462400"; d="scan'208";a="400478900" Received: from yhuang6-desk1.sh.intel.com (HELO yhuang6-desk1.ccr.corp.intel.com) ([10.239.13.1]) by orsmga002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Apr 2021 19:15:10 -0700 From: "Huang, Ying" To: Miaohe Lin Cc: , , , , , , , , , , , , Subject: Re: [PATCH v2 5/5] mm/shmem: fix shmem_swapin() race with swapoff References: <20210417094039.51711-1-linmiaohe@huawei.com> <20210417094039.51711-6-linmiaohe@huawei.com> Date: Mon, 19 Apr 2021 10:15:08 +0800 In-Reply-To: <20210417094039.51711-6-linmiaohe@huawei.com> (Miaohe Lin's message of "Sat, 17 Apr 2021 05:40:39 -0400") Message-ID: <87r1j7kok3.fsf@yhuang6-desk1.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Miaohe Lin writes: > When I was investigating the swap code, I found the below possible race > window: > > CPU 1 CPU 2 > ----- ----- > shmem_swapin > swap_cluster_readahead > if (likely(si->flags & (SWP_BLKDEV | SWP_FS_OPS))) { > swapoff > si->flags &= ~SWP_VALID; > .. > synchronize_rcu(); > .. You have removed these code in the previous patches of the series. And they are not relevant in this patch. > si->swap_file = NULL; > struct inode *inode = si->swap_file->f_mapping->host;[oops!] > > Close this race window by using get/put_swap_device() to guard against > concurrent swapoff. > > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") No. This isn't the commit that introduces the race condition. Please recheck your git blame result. Best Regards, Huang, Ying > Signed-off-by: Miaohe Lin > --- > mm/shmem.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/mm/shmem.c b/mm/shmem.c > index 26c76b13ad23..936ba5595297 100644 > --- a/mm/shmem.c > +++ b/mm/shmem.c > @@ -1492,15 +1492,21 @@ static void shmem_pseudo_vma_destroy(struct vm_area_struct *vma) > static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp, > struct shmem_inode_info *info, pgoff_t index) > { > + struct swap_info_struct *si; > struct vm_area_struct pvma; > struct page *page; > struct vm_fault vmf = { > .vma = &pvma, > }; > > + /* Prevent swapoff from happening to us. */ > + si = get_swap_device(swap); > + if (unlikely(!si)) > + return NULL; > shmem_pseudo_vma_init(&pvma, info, index); > page = swap_cluster_readahead(swap, gfp, &vmf); > shmem_pseudo_vma_destroy(&pvma); > + put_swap_device(si); > > return page; > } 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=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 D7535C433ED for ; Mon, 19 Apr 2021 02:15:18 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 7C69C610CA for ; Mon, 19 Apr 2021 02:15:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7C69C610CA Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id AD0CE6B0036; Sun, 18 Apr 2021 22:15:17 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A7FF16B006E; Sun, 18 Apr 2021 22:15:17 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 920CB6B0070; Sun, 18 Apr 2021 22:15:17 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 779506B0036 for ; Sun, 18 Apr 2021 22:15:17 -0400 (EDT) Received: from smtpin08.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 229794DC8 for ; Mon, 19 Apr 2021 02:15:17 +0000 (UTC) X-FDA: 78047499474.08.D556EAB Received: from mga06.intel.com (mga06.intel.com [134.134.136.31]) by imf30.hostedemail.com (Postfix) with ESMTP id 904D3E00010E for ; Mon, 19 Apr 2021 02:15:02 +0000 (UTC) IronPort-SDR: k/i4iXdXXKiJA0W7j8ix7FfSO8/Z87Gm1ujs1gO4Cof889RByJnSCxESzYriMV7sqvHWliD7LS D5VD8Ajs8Maw== X-IronPort-AV: E=McAfee;i="6200,9189,9958"; a="256567873" X-IronPort-AV: E=Sophos;i="5.82,232,1613462400"; d="scan'208";a="256567873" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Apr 2021 19:15:14 -0700 IronPort-SDR: iJjwYR+WlUCHdbwjvyCtNT+ukBMAkaTydHU70GJ1WrjiN6l+88DpV2LJgzaiQkjgeJ/vQ5RyFg FAqkOlPBbhfw== X-IronPort-AV: E=Sophos;i="5.82,232,1613462400"; d="scan'208";a="400478900" Received: from yhuang6-desk1.sh.intel.com (HELO yhuang6-desk1.ccr.corp.intel.com) ([10.239.13.1]) by orsmga002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Apr 2021 19:15:10 -0700 From: "Huang, Ying" To: Miaohe Lin Cc: , , , , , , , , , , , , Subject: Re: [PATCH v2 5/5] mm/shmem: fix shmem_swapin() race with swapoff References: <20210417094039.51711-1-linmiaohe@huawei.com> <20210417094039.51711-6-linmiaohe@huawei.com> Date: Mon, 19 Apr 2021 10:15:08 +0800 In-Reply-To: <20210417094039.51711-6-linmiaohe@huawei.com> (Miaohe Lin's message of "Sat, 17 Apr 2021 05:40:39 -0400") Message-ID: <87r1j7kok3.fsf@yhuang6-desk1.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 904D3E00010E X-Stat-Signature: mwxef4ihzscfyauuydetedu743jwpnis Received-SPF: none (intel.com>: No applicable sender policy available) receiver=imf30; identity=mailfrom; envelope-from=""; helo=mga06.intel.com; client-ip=134.134.136.31 X-HE-DKIM-Result: none/none X-HE-Tag: 1618798502-454214 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Miaohe Lin writes: > When I was investigating the swap code, I found the below possible race > window: > > CPU 1 CPU 2 > ----- ----- > shmem_swapin > swap_cluster_readahead > if (likely(si->flags & (SWP_BLKDEV | SWP_FS_OPS))) { > swapoff > si->flags &= ~SWP_VALID; > .. > synchronize_rcu(); > .. You have removed these code in the previous patches of the series. And they are not relevant in this patch. > si->swap_file = NULL; > struct inode *inode = si->swap_file->f_mapping->host;[oops!] > > Close this race window by using get/put_swap_device() to guard against > concurrent swapoff. > > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") No. This isn't the commit that introduces the race condition. Please recheck your git blame result. Best Regards, Huang, Ying > Signed-off-by: Miaohe Lin > --- > mm/shmem.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/mm/shmem.c b/mm/shmem.c > index 26c76b13ad23..936ba5595297 100644 > --- a/mm/shmem.c > +++ b/mm/shmem.c > @@ -1492,15 +1492,21 @@ static void shmem_pseudo_vma_destroy(struct vm_area_struct *vma) > static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp, > struct shmem_inode_info *info, pgoff_t index) > { > + struct swap_info_struct *si; > struct vm_area_struct pvma; > struct page *page; > struct vm_fault vmf = { > .vma = &pvma, > }; > > + /* Prevent swapoff from happening to us. */ > + si = get_swap_device(swap); > + if (unlikely(!si)) > + return NULL; > shmem_pseudo_vma_init(&pvma, info, index); > page = swap_cluster_readahead(swap, gfp, &vmf); > shmem_pseudo_vma_destroy(&pvma); > + put_swap_device(si); > > return page; > }