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[2620:137:e000::1:20]) by mx.google.com with ESMTP id q126-20020a634384000000b0041a6772b82esi14405210pga.785.2022.07.25.05.55.35; Mon, 25 Jul 2022 05:55:51 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20210112 header.b="d3/Pmsvi"; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234808AbiGYMp0 (ORCPT + 99 others); Mon, 25 Jul 2022 08:45:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50132 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233546AbiGYMpZ (ORCPT ); Mon, 25 Jul 2022 08:45:25 -0400 Received: from mail-lj1-x231.google.com (mail-lj1-x231.google.com [IPv6:2a00:1450:4864:20::231]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 55DBC6407 for ; Mon, 25 Jul 2022 05:45:24 -0700 (PDT) Received: by mail-lj1-x231.google.com with SMTP id w18so1910526lje.1 for ; Mon, 25 Jul 2022 05:45:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=jc/BDHMhK7iVrMHxH2raQUC5msig51Chw85BZlvexog=; b=d3/PmsviXYCk0itavdxDqkvzp8Kz9cccCIGsW5lkbDT80suAiNOcyPvQwiEya3G4Mf e0LrE0W4gpboiQ9zI5/nYBW3ry4+9nQUWZz1VV6DufjOI36YRFkFznXf9NFTGtG9xVLR mJNtZGy+xADkT3tKDanfBBdZ5ZFKpsQq/Op/BB4FaABjvB9ZzlIwiaCHh1XJE570mDVq /aAyku306M+TRH2XHHNJOxt1kd1UFqhQSJGWI5k0gJStQQliTfMuSzwp1DxmA6/I6wnf 045ou4K6VM40gyDik9i7VB7HFSavn6ixutQ86mfaCKiTwF7I9uuiMbiYDroAvgzVbo84 6XXA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=jc/BDHMhK7iVrMHxH2raQUC5msig51Chw85BZlvexog=; b=iSixGbl0l+J6MCMMhElQAr9PyxpvDg4Jdf+LpemGEEbbS9NYUqj6XhiBPvT4VaO0PZ F5HIDeBYfevWApgiciuidXwcjnRIMgRfQlYb+rIB90J/tjj6WbZfLjitvUq1d5hkXbFg C4t4Vi6tESbjXV9h7D9Y5KorGzrK2vjl1hpllXPjPwQrQPRiaayjkBHZLdY0GesiJpwf K52Tct6xVSC8KfpkRrNa4e7F3dkpMneiynn4PFGnzTEo7U4jykPlIUcv3b2XkrbfURDD K9Nl6wIl0a9E0guc6f4/J6+6dzzDUgxy2FDRbSHyXI1l/oEdlOo3/wzjxbP6YvGex26A RP+g== X-Gm-Message-State: AJIora8CDHeadO1SBOV/M7QSLpoxa9SNk11KvxTHlpDy2j42GWPTeuJU OTaqqptyUFA9pjrsLfL6yq7bNJ7lLERyrL6CF45zXg== X-Received: by 2002:a2e:bd0e:0:b0:25a:88b3:9af6 with SMTP id n14-20020a2ebd0e000000b0025a88b39af6mr4397667ljq.363.1658753120669; Mon, 25 Jul 2022 05:45:20 -0700 (PDT) MIME-Version: 1.0 References: <000000000000e6917605e48ce2bf@google.com> In-Reply-To: From: Dmitry Vyukov Date: Mon, 25 Jul 2022 14:45:08 +0200 Message-ID: Subject: Re: [syzbot] WARNING in p9_client_destroy To: asmadeus@codewreck.org Cc: Vlastimil Babka , syzbot , akpm@linux-foundation.org, davem@davemloft.net, edumazet@google.com, elver@google.com, ericvh@gmail.com, hdanton@sina.com, k.kahurani@gmail.com, kuba@kernel.org, linux-kernel@vger.kernel.org, linux_oss@crudebyte.com, lucho@ionkov.net, netdev@vger.kernel.org, pabeni@redhat.com, rientjes@google.com, syzkaller-bugs@googlegroups.com, torvalds@linux-foundation.org, v9fs-developer@lists.sourceforge.net Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-17.6 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, ENV_AND_HDR_SPF_MATCH,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS, USER_IN_DEF_DKIM_WL,USER_IN_DEF_SPF_WL autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 25 Jul 2022 at 13:51, wrote: > > Vlastimil Babka wrote on Mon, Jul 25, 2022 at 12:15:24PM +0200: > > On 7/24/22 15:17, syzbot wrote: > > > syzbot has bisected this issue to: > > > > > > commit 7302e91f39a81a9c2efcf4bc5749d18128366945 > > > Author: Marco Elver > > > Date: Fri Jan 14 22:03:58 2022 +0000 > > > > > > mm/slab_common: use WARN() if cache still has objects on destroy > > > > Just to state the obvious, bisection pointed to a commit that added the > > warning, but the reason for the warning would be that p9 is destroying a > > kmem_cache without freeing all the objects there first, and that would be > > true even before the commit. > > Probably true from the moment that cache/idr was introduced... I've got > a couple of fixes in next but given syzcaller claims that's the tree it > was produced on I guess there can be more such leaks. > (well, the lines it sent in the backtrace yesterday don't match next, > but I wouldn't count on it) > > If someone wants to have a look please feel free, I would bet the > problem is just that p9_fd_close() doesn't call or does something > equivalent to p9_conn_cancel() and there just are some requests that > haven't been sent yet when the mount is closed.. > But I don't have/can/want to take the time to check right now as I > consider such a leak harmless enough, someone has to be root or > equivalent to do 9p mounts in most cases. FWIW with KASAN we have allocation stacks for each heap object. So when KASAN is enabled that warning could list all live object allocation stacks.