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=-6.6 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLACK,USER_AGENT_SANE_1 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 EED8EC433DF for ; Mon, 24 Aug 2020 12:21:58 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C699F20838 for ; Mon, 24 Aug 2020 12:21:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C699F20838 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 564E16B0002; Mon, 24 Aug 2020 08:21:58 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5155D6B0006; Mon, 24 Aug 2020 08:21:58 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 403806B000A; Mon, 24 Aug 2020 08:21:58 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0155.hostedemail.com [216.40.44.155]) by kanga.kvack.org (Postfix) with ESMTP id 2B0F96B0002 for ; Mon, 24 Aug 2020 08:21:58 -0400 (EDT) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id D2C00181AC9CC for ; Mon, 24 Aug 2020 12:21:57 +0000 (UTC) X-FDA: 77185373874.17.ocean01_520231927053 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin17.hostedemail.com (Postfix) with ESMTP id 94AD2180D0180 for ; Mon, 24 Aug 2020 12:21:57 +0000 (UTC) X-HE-Tag: ocean01_520231927053 X-Filterd-Recvd-Size: 1985 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf18.hostedemail.com (Postfix) with ESMTP for ; Mon, 24 Aug 2020 12:21:57 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 066CDAC7F; Mon, 24 Aug 2020 12:22:26 +0000 (UTC) Date: Mon, 24 Aug 2020 14:21:52 +0200 From: Oscar Salvador To: nao.horiguchi@gmail.com Cc: linux-mm@kvack.org, mhocko@kernel.org, akpm@linux-foundation.org, mike.kravetz@oracle.com, tony.luck@intel.com, david@redhat.com, aneesh.kumar@linux.vnet.ibm.com, zeil@yandex-team.ru, cai@lca.pw, naoya.horiguchi@nec.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH v6 12/12] mm,hwpoison: double-check page count in __get_any_page() Message-ID: <20200824122151.GC7491@linux> References: <20200806184923.7007-1-nao.horiguchi@gmail.com> <20200806184923.7007-13-nao.horiguchi@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200806184923.7007-13-nao.horiguchi@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Rspamd-Queue-Id: 94AD2180D0180 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam02 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000014, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Aug 06, 2020 at 06:49:23PM +0000, nao.horiguchi@gmail.com wrote: > From: Naoya Horiguchi > > Soft offlining could fail with EIO due to the race condition with > hugepage migration. This issuse became visible due to the change by > previous patch that makes soft offline handler take page refcount > by its own. We have no way to directly pin zero refcount page, and > the page considered as a zero refcount page could be allocated just > after the first check. > > This patch adds the second check to find the race and gives us > chance to handle it more reliably. > > Reported-by: Qian Cai > Signed-off-by: Naoya Horiguchi Reviewed-by: Oscar Salvador -- Oscar Salvador SUSE L3