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 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 2879EC4332F for ; Fri, 21 Oct 2022 05:48:47 +0000 (UTC) Received: from localhost ([::1] helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1olkth-00060s-VA for qemu-devel@archiver.kernel.org; Fri, 21 Oct 2022 01:48:45 -0400 Received: from [::1] (helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1olkiT-0001Hk-M2 for qemu-devel@archiver.kernel.org; Fri, 21 Oct 2022 01:37:09 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1olkiO-0001B9-FO for qemu-devel@nongnu.org; Fri, 21 Oct 2022 01:37:04 -0400 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1olkiL-0008Ju-T2 for qemu-devel@nongnu.org; Fri, 21 Oct 2022 01:37:03 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 0B01061D9D; Fri, 21 Oct 2022 05:37:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DD180C433C1; Fri, 21 Oct 2022 05:36:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1666330619; bh=C4x6hYFDAWi4DXcimrF67aLQPsZW93Mx96V0amCnWn8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=QlbKpgGx1qrMgSdaJyivXXf5qor/X961lpc0yRR+woSzH3tCcgiu1gmz/NBYEXQfe K4vsmjcCVpegODndBu2vg9R9eT4zstEkXIb1SfoFeTNCPoQOhnVD+4siGARAhiytQw tUVK0o7ipMo473nLX2GyW5d8TYlaC0oYKW+aMHhw= Date: Fri, 21 Oct 2022 07:37:48 +0200 From: Greg KH To: Luben Tuikov Cc: Yang Yingliang , linux-kernel@vger.kernel.org, qemu-devel@nongnu.org, linux-f2fs-devel@lists.sourceforge.net, linux-erofs@lists.ozlabs.org, ocfs2-devel@oss.oracle.com, linux-mtd@lists.infradead.org, amd-gfx@lists.freedesktop.org, rafael@kernel.org, somlo@cmu.edu, mst@redhat.com, jaegeuk@kernel.org, chao@kernel.org, hsiangkao@linux.alibaba.com, huangjianan@oppo.com, mark@fasheh.com, jlbec@evilplan.org, joseph.qi@linux.alibaba.com, akpm@linux-foundation.org, alexander.deucher@amd.com, richard@nod.at, liushixin2@huawei.com Subject: Re: [PATCH 00/11] fix memory leak while kset_register() fails Message-ID: References: <20221021022102.2231464-1-yangyingliang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Received-SPF: pass client-ip=2604:1380:4641:c500::1; envelope-from=gregkh@linuxfoundation.org; helo=dfw.source.kernel.org X-Spam_score_int: -73 X-Spam_score: -7.4 X-Spam_bar: ------- X-Spam_report: (-7.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.251, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_HI=-5, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, Oct 21, 2022 at 01:29:31AM -0400, Luben Tuikov wrote: > On 2022-10-20 22:20, Yang Yingliang wrote: > > The previous discussion link: > > https://lore.kernel.org/lkml/0db486eb-6927-927e-3629-958f8f211194@huawei.com/T/ > > The very first discussion on this was here: > > https://www.spinics.net/lists/dri-devel/msg368077.html > > Please use this link, and not the that one up there you which quoted above, > and whose commit description is taken verbatim from the this link. > > > > > kset_register() is currently used in some places without calling > > kset_put() in error path, because the callers think it should be > > kset internal thing to do, but the driver core can not know what > > caller doing with that memory at times. The memory could be freed > > both in kset_put() and error path of caller, if it is called in > > kset_register(). > > As I explained in the link above, the reason there's > a memory leak is that one cannot call kset_register() without > the kset->kobj.name being set--kobj_add_internal() returns -EINVAL, > in this case, i.e. kset_register() fails with -EINVAL. > > Thus, the most common usage is something like this: > > kobj_set_name(&kset->kobj, format, ...); > kset->kobj.kset = parent_kset; > kset->kobj.ktype = ktype; > res = kset_register(kset); > > So, what is being leaked, is the memory allocated in kobj_set_name(), > by the common idiom shown above. This needs to be mentioned in > the documentation, at least, in case, in the future this is absolved > in kset_register() redesign, etc. Based on this, can kset_register() just clean up from itself when an error happens? Ideally that would be the case, as the odds of a kset being embedded in a larger structure is probably slim, but we would have to search the tree to make sure. thanks, greg k-h