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=-3.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 CBFFBC433DF for ; Sat, 10 Oct 2020 00:26:33 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 46E5722248 for ; Sat, 10 Oct 2020 00:26:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 46E5722248 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 762486B006E; Fri, 9 Oct 2020 20:26:32 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6EBAA6B0070; Fri, 9 Oct 2020 20:26:32 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5B2036B0071; Fri, 9 Oct 2020 20:26:32 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0095.hostedemail.com [216.40.44.95]) by kanga.kvack.org (Postfix) with ESMTP id 2A8F86B006E for ; Fri, 9 Oct 2020 20:26:32 -0400 (EDT) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id B8B84824999B for ; Sat, 10 Oct 2020 00:26:31 +0000 (UTC) X-FDA: 77354124582.17.front04_59137f5271e4 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin17.hostedemail.com (Postfix) with ESMTP id 9B1AC180D0184 for ; Sat, 10 Oct 2020 00:26:31 +0000 (UTC) X-HE-Tag: front04_59137f5271e4 X-Filterd-Recvd-Size: 2540 Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by imf38.hostedemail.com (Postfix) with ESMTP for ; Sat, 10 Oct 2020 00:26:30 +0000 (UTC) IronPort-SDR: X10guHr3HnIzm0Fwq1g4xGjF6i2sllyoORCKGR3zpS6yLPgWjNNkVhBPnuVXC2C9yUbkshou7H qbsMi2wODN8w== X-IronPort-AV: E=McAfee;i="6000,8403,9769"; a="162912931" X-IronPort-AV: E=Sophos;i="5.77,357,1596524400"; d="scan'208";a="162912931" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Oct 2020 17:26:28 -0700 IronPort-SDR: 5ePig7T99IXUzWtaUC9ICLZ7NtCQnvXRIXwwjMvIVfN6FJI/cfVIFsk/SetacBKMYJQuwx9UUl /otEad6RQUWg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.77,357,1596524400"; d="scan'208";a="317208202" Received: from yhuang-dev.sh.intel.com (HELO yhuang-dev) ([10.239.159.65]) by orsmga006.jf.intel.com with ESMTP; 09 Oct 2020 17:26:26 -0700 From: "Huang\, Ying" To: Matthew Wilcox Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Rafael Aquini , Hugh Dickins , "Kirill A . Shutemov" , Andrea Arcangeli Subject: Re: [PATCH] mm: Fix a race during split THP References: <20201009073647.1531083-1-ying.huang@intel.com> <20201009132704.GS20115@casper.infradead.org> Date: Sat, 10 Oct 2020 08:26:26 +0800 In-Reply-To: <20201009132704.GS20115@casper.infradead.org> (Matthew Wilcox's message of "Fri, 9 Oct 2020 14:27:04 +0100") Message-ID: <87362n7wp9.fsf@yhuang-dev.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii 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: Matthew Wilcox writes: > On Fri, Oct 09, 2020 at 03:36:47PM +0800, Huang, Ying wrote: >> + if (PageSwapCache(head)) { >> + swp_entry_t entry = { .val = page_private(head) }; >> + >> + split_swap_cluster(entry); >> + } > ... >> - if (PageSwapCache(head)) { >> - swp_entry_t entry = { .val = page_private(head) }; >> - >> - ret = split_swap_cluster(entry); > > Are we sure split_swap_cluster() can't fail? Or if it does fail, it's > OK to continue with the split and not report the error? split_swap_cluster() can only fail for invalid swap entry. Which isn't expected to happen in this situation. Best Regards, Huang, Ying