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=-8.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 263B3C4346E for ; Fri, 25 Sep 2020 02:59:18 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9370220838 for ; Fri, 25 Sep 2020 02:59:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="F5JoiH8A" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9370220838 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 0645B6B005C; Thu, 24 Sep 2020 22:59:17 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 015366B005D; Thu, 24 Sep 2020 22:59:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E6C2A6B0062; Thu, 24 Sep 2020 22:59:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0100.hostedemail.com [216.40.44.100]) by kanga.kvack.org (Postfix) with ESMTP id D16976B005C for ; Thu, 24 Sep 2020 22:59:16 -0400 (EDT) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 93785181AE863 for ; Fri, 25 Sep 2020 02:59:16 +0000 (UTC) X-FDA: 77300077512.22.oil78_620416327164 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin22.hostedemail.com (Postfix) with ESMTP id 6FCAD18038E60 for ; Fri, 25 Sep 2020 02:59:16 +0000 (UTC) X-HE-Tag: oil78_620416327164 X-Filterd-Recvd-Size: 2955 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf34.hostedemail.com (Postfix) with ESMTP for ; Fri, 25 Sep 2020 02:59:16 +0000 (UTC) Received: from X1 (unknown [104.245.68.101]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D4DC620838; Fri, 25 Sep 2020 02:59:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601002755; bh=HlyAAdYR9wyHbMonermc2egT8gBMGqZa8uXyB8IhXjU=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=F5JoiH8AKJ04sDI6xltJ+S5/vIuoZ5y0YVdFce44I1ipKaIvaAksqmplesJ3DHsNm orqNUbtTJo2z9rY2GduEN63JeYOl4xlHV09v4dEtYTK1TyEKk02AI8jKbNd9c7/E+V m6QdEhN2hXLtO9lQ9kYvbD2v1IVCtSvvSTKvU8go= Date: Thu, 24 Sep 2020 19:59:14 -0700 From: Andrew Morton To: Rafael Aquini Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, ying.huang@intel.com Subject: Re: [PATCH] mm: swapfile: avoid split_swap_cluster() NULL pointer dereference Message-Id: <20200924195914.d240877a10e22b457bd9b45d@linux-foundation.org> In-Reply-To: <20200923134251.GN795820@optiplex-lnx> References: <20200922184838.978540-1-aquini@redhat.com> <20200922124750.67a20d9764ec098b17705407@linux-foundation.org> <20200923134251.GN795820@optiplex-lnx> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit 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: On Wed, 23 Sep 2020 09:42:51 -0400 Rafael Aquini wrote: > On Tue, Sep 22, 2020 at 12:47:50PM -0700, Andrew Morton wrote: > > On Tue, 22 Sep 2020 14:48:38 -0400 Rafael Aquini wrote: > > > > > The swap area descriptor only gets struct swap_cluster_info *cluster_info > > > allocated if the swapfile is backed by non-rotational storage. > > > When the swap area is laid on top of ordinary disk spindles, lock_cluster() > > > will naturally return NULL. > > > > > > CONFIG_THP_SWAP exposes cluster_info infrastructure to a broader number of > > > use cases, and split_swap_cluster(), which is the counterpart of split_huge_page() > > > for the THPs in the swapcache, misses checking the return of lock_cluster before > > > operating on the cluster_info pointer. > > > > > > This patch addresses that issue by adding a proper check for the pointer > > > not being NULL in the wrappers cluster_{is,clear}_huge(), in order to avoid > > > crashes similar to the one below: > > > > > > ... > > > > > > Fixes: 59807685a7e77 ("mm, THP, swap: support splitting THP for THP swap out") > > > Signed-off-by: Rafael Aquini > > > > Did you consider cc:stable? > > > > UGH! I missed adding it to my cc list. Shall I just forward it, now, or > do you prefer a fresh repost? I added the cc:stable to my copy.