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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7B13BC4332F for ; Fri, 21 Oct 2022 09:56:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229731AbiJUJ4m (ORCPT ); Fri, 21 Oct 2022 05:56:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39998 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229558AbiJUJ4e (ORCPT ); Fri, 21 Oct 2022 05:56:34 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CD9F01ACA9F for ; Fri, 21 Oct 2022 02:56:29 -0700 (PDT) Received: from dggpemm500021.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4Mv09R6B5NzmVJg; Fri, 21 Oct 2022 17:51:39 +0800 (CST) Received: from dggpemm500007.china.huawei.com (7.185.36.183) by dggpemm500021.china.huawei.com (7.185.36.109) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 21 Oct 2022 17:56:21 +0800 Received: from [10.174.178.174] (10.174.178.174) by dggpemm500007.china.huawei.com (7.185.36.183) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 21 Oct 2022 17:56:20 +0800 Subject: Re: [PATCH 00/11] fix memory leak while kset_register() fails To: Luben Tuikov , Greg KH CC: , , , , , , , , , , , , , , , , , , , , References: <20221021022102.2231464-1-yangyingliang@huawei.com> <0591e66f-731a-5f81-fc9d-3a6d80516c65@huawei.com> <78f84006-955f-6209-1cae-024e4f199b97@amd.com> From: Yang Yingliang Message-ID: <9ee10048-f3fe-533b-5f00-8e5dd176808e@huawei.com> Date: Fri, 21 Oct 2022 17:56:19 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <78f84006-955f-6209-1cae-024e4f199b97@amd.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Originating-IP: [10.174.178.174] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpemm500007.china.huawei.com (7.185.36.183) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/10/21 17:08, Luben Tuikov wrote: > On 2022-10-21 04:59, Yang Yingliang wrote: >> On 2022/10/21 16:36, Greg KH wrote: >>> On Fri, Oct 21, 2022 at 04:24:23PM +0800, Yang Yingliang wrote: >>>> On 2022/10/21 13:37, Greg KH wrote: >>>>> 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://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Flkml%2F0db486eb-6927-927e-3629-958f8f211194%40huawei.com%2FT%2F&data=05%7C01%7Cluben.tuikov%40amd.com%7C74aa9b57192b406ef27408dab3429db4%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C638019395979868103%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=RcK05cXm1J5%2BtYcLO2SMG7k6sjeymQzdBzMCDJSzfdE%3D&reserved=0 >>>>>> The very first discussion on this was here: >>>>>> >>>>>> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.spinics.net%2Flists%2Fdri-devel%2Fmsg368077.html&data=05%7C01%7Cluben.tuikov%40amd.com%7C74aa9b57192b406ef27408dab3429db4%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C638019395979868103%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=sHZ6kfLF8HxrNXV6%2FVjgdH%2BmQM4T3Zv0U%2FAwddT97cE%3D&reserved=0 >>>>>> >>>>>> 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. >>>> I have search the whole tree, the kset used in bus_register() - patch #3, >>>> kset_create_and_add() - patch #4 >>>> __class_register() - patch #5,  fw_cfg_build_symlink() - patch #6 and >>>> amdgpu_discovery.c - patch #10 >>>> is embedded in a larger structure. In these cases, we can not call >>>> kset_put() in error path in kset_register() >>> Yes you can as the kobject in the kset should NOT be controling the >>> lifespan of those larger objects. >>> >>> If it is, please point out the call chain here as I don't think that >>> should be possible. >>> >>> Note all of this is a mess because the kobject name stuff was added much >>> later, after the driver model had been created and running for a while. >>> We missed this error path when adding the dynamic kobject name logic, >>> thank for looking into this. >>> >>> If you could test the patch posted with your error injection systems, >>> that could make this all much simpler to solve. >> The patch posted by Luben will cause double free in some cases. > Yes, I figured this out in the other email and posted the scenario Greg > was asking about. > > But I believe the question still stands if we can do kset_put() > after a *failed* kset_register(), namely if more is being done than > necessary, which is just to free the memory allocated by > kobject_set_name(). The name memory is allocated in kobject_set_name() in caller,  and I think caller free the memory that it allocated is reasonable, it's weird that some callers allocate some memory and use function (kset_register) failed, then it free the memory allocated in callers,  I think use kset_put()/kfree_const(name) in caller seems more reasonable. Thanks, Yang > > Regards, > Luben > . 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(TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.95) id 1ololZ-0001Tp-0q for linux-f2fs-devel@lists.sourceforge.net; Fri, 21 Oct 2022 09:56:42 +0000 Received: from dggpemm500021.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4Mv09R6B5NzmVJg; Fri, 21 Oct 2022 17:51:39 +0800 (CST) Received: from dggpemm500007.china.huawei.com (7.185.36.183) by dggpemm500021.china.huawei.com (7.185.36.109) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 21 Oct 2022 17:56:21 +0800 Received: from [10.174.178.174] (10.174.178.174) by dggpemm500007.china.huawei.com (7.185.36.183) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 21 Oct 2022 17:56:20 +0800 To: Luben Tuikov , Greg KH References: <20221021022102.2231464-1-yangyingliang@huawei.com> <0591e66f-731a-5f81-fc9d-3a6d80516c65@huawei.com> <78f84006-955f-6209-1cae-024e4f199b97@amd.com> Message-ID: <9ee10048-f3fe-533b-5f00-8e5dd176808e@huawei.com> Date: Fri, 21 Oct 2022 17:56:19 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <78f84006-955f-6209-1cae-024e4f199b97@amd.com> Content-Language: en-US X-Originating-IP: [10.174.178.174] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpemm500007.china.huawei.com (7.185.36.183) X-CFilter-Loop: Reflected X-Headers-End: 1ololZ-0001Tp-0q Subject: Re: [f2fs-dev] [PATCH 00/11] fix memory leak while kset_register() fails X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Yang Yingliang via Linux-f2fs-devel Reply-To: Yang Yingliang Cc: rafael@kernel.org, qemu-devel@nongnu.org, richard@nod.at, somlo@cmu.edu, mst@redhat.com, linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org, linux-f2fs-devel@lists.sourceforge.net, liushixin2@huawei.com, joseph.qi@linux.alibaba.com, linux-mtd@lists.infradead.org, jlbec@evilplan.org, hsiangkao@linux.alibaba.com, alexander.deucher@amd.com, jaegeuk@kernel.org, akpm@linux-foundation.org, linux-erofs@lists.ozlabs.org, mark@fasheh.com, ocfs2-devel@oss.oracle.com Content-Transfer-Encoding: base64 Content-Type: text/plain; charset="utf-8"; Format="flowed" Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net Ck9uIDIwMjIvMTAvMjEgMTc6MDgsIEx1YmVuIFR1aWtvdiB3cm90ZToKPiBPbiAyMDIyLTEwLTIx IDA0OjU5LCBZYW5nIFlpbmdsaWFuZyB3cm90ZToKPj4gT24gMjAyMi8xMC8yMSAxNjozNiwgR3Jl ZyBLSCB3cm90ZToKPj4+IE9uIEZyaSwgT2N0IDIxLCAyMDIyIGF0IDA0OjI0OjIzUE0gKzA4MDAs IFlhbmcgWWluZ2xpYW5nIHdyb3RlOgo+Pj4+IE9uIDIwMjIvMTAvMjEgMTM6MzcsIEdyZWcgS0gg d3JvdGU6Cj4+Pj4+IE9uIEZyaSwgT2N0IDIxLCAyMDIyIGF0IDAxOjI5OjMxQU0gLTA0MDAsIEx1 YmVuIFR1aWtvdiB3cm90ZToKPj4+Pj4+IE9uIDIwMjItMTAtMjAgMjI6MjAsIFlhbmcgWWluZ2xp 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4Mv09R6B5NzmVJg; Fri, 21 Oct 2022 17:51:39 +0800 (CST) Received: from dggpemm500007.china.huawei.com (7.185.36.183) by dggpemm500021.china.huawei.com (7.185.36.109) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 21 Oct 2022 17:56:21 +0800 Received: from [10.174.178.174] (10.174.178.174) by dggpemm500007.china.huawei.com (7.185.36.183) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 21 Oct 2022 17:56:20 +0800 Subject: Re: [PATCH 00/11] fix memory leak while kset_register() fails To: Luben Tuikov , Greg KH CC: , , , , , , , , , , , , , , , , , , , , References: <20221021022102.2231464-1-yangyingliang@huawei.com> <0591e66f-731a-5f81-fc9d-3a6d80516c65@huawei.com> <78f84006-955f-6209-1cae-024e4f199b97@amd.com> From: Yang Yingliang Message-ID: <9ee10048-f3fe-533b-5f00-8e5dd176808e@huawei.com> Date: Fri, 21 Oct 2022 17:56:19 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <78f84006-955f-6209-1cae-024e4f199b97@amd.com> Content-Language: en-US X-Originating-IP: [10.174.178.174] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpemm500007.china.huawei.com (7.185.36.183) X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221021_025630_672776_6C6A6103 X-CRM114-Status: GOOD ( 23.45 ) X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: base64 Content-Type: text/plain; charset="utf-8"; Format="flowed" Sender: "linux-mtd" Errors-To: linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org Ck9uIDIwMjIvMTAvMjEgMTc6MDgsIEx1YmVuIFR1aWtvdiB3cm90ZToKPiBPbiAyMDIyLTEwLTIx 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with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4Mv0Hh6mL4z3c8j for ; Fri, 21 Oct 2022 20:57:01 +1100 (AEDT) Received: from dggpemm500021.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4Mv09R6B5NzmVJg; Fri, 21 Oct 2022 17:51:39 +0800 (CST) Received: from dggpemm500007.china.huawei.com (7.185.36.183) by dggpemm500021.china.huawei.com (7.185.36.109) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 21 Oct 2022 17:56:21 +0800 Received: from [10.174.178.174] (10.174.178.174) by dggpemm500007.china.huawei.com (7.185.36.183) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 21 Oct 2022 17:56:20 +0800 Subject: Re: [PATCH 00/11] fix memory leak while kset_register() fails To: Luben Tuikov , Greg KH References: <20221021022102.2231464-1-yangyingliang@huawei.com> <0591e66f-731a-5f81-fc9d-3a6d80516c65@huawei.com> <78f84006-955f-6209-1cae-024e4f199b97@amd.com> Message-ID: <9ee10048-f3fe-533b-5f00-8e5dd176808e@huawei.com> Date: Fri, 21 Oct 2022 17:56:19 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <78f84006-955f-6209-1cae-024e4f199b97@amd.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Originating-IP: [10.174.178.174] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpemm500007.china.huawei.com (7.185.36.183) X-CFilter-Loop: Reflected X-BeenThere: linux-erofs@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Development of Linux EROFS file system List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Yang Yingliang via Linux-erofs Reply-To: Yang Yingliang Cc: rafael@kernel.org, qemu-devel@nongnu.org, richard@nod.at, somlo@cmu.edu, mst@redhat.com, linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org, linux-f2fs-devel@lists.sourceforge.net, liushixin2@huawei.com, joseph.qi@linux.alibaba.com, linux-mtd@lists.infradead.org, jlbec@evilplan.org, hsiangkao@linux.alibaba.com, alexander.deucher@amd.com, jaegeuk@kernel.org, akpm@linux-foundation.org, huangjianan@oppo.com, linux-erofs@lists.ozlabs.org, mark@fasheh.com, ocfs2-devel@oss.oracle.com Errors-To: linux-erofs-bounces+linux-erofs=archiver.kernel.org@lists.ozlabs.org Sender: "Linux-erofs" On 2022/10/21 17:08, Luben Tuikov wrote: > On 2022-10-21 04:59, Yang Yingliang wrote: >> On 2022/10/21 16:36, Greg KH wrote: >>> On Fri, Oct 21, 2022 at 04:24:23PM +0800, Yang Yingliang wrote: >>>> On 2022/10/21 13:37, Greg KH wrote: >>>>> 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://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Flkml%2F0db486eb-6927-927e-3629-958f8f211194%40huawei.com%2FT%2F&data=05%7C01%7Cluben.tuikov%40amd.com%7C74aa9b57192b406ef27408dab3429db4%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C638019395979868103%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=RcK05cXm1J5%2BtYcLO2SMG7k6sjeymQzdBzMCDJSzfdE%3D&reserved=0 >>>>>> The very first discussion on this was here: >>>>>> >>>>>> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.spinics.net%2Flists%2Fdri-devel%2Fmsg368077.html&data=05%7C01%7Cluben.tuikov%40amd.com%7C74aa9b57192b406ef27408dab3429db4%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C638019395979868103%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=sHZ6kfLF8HxrNXV6%2FVjgdH%2BmQM4T3Zv0U%2FAwddT97cE%3D&reserved=0 >>>>>> >>>>>> 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. >>>> I have search the whole tree, the kset used in bus_register() - patch #3, >>>> kset_create_and_add() - patch #4 >>>> __class_register() - patch #5,  fw_cfg_build_symlink() - patch #6 and >>>> amdgpu_discovery.c - patch #10 >>>> is embedded in a larger structure. In these cases, we can not call >>>> kset_put() in error path in kset_register() >>> Yes you can as the kobject in the kset should NOT be controling the >>> lifespan of those larger objects. >>> >>> If it is, please point out the call chain here as I don't think that >>> should be possible. >>> >>> Note all of this is a mess because the kobject name stuff was added much >>> later, after the driver model had been created and running for a while. >>> We missed this error path when adding the dynamic kobject name logic, >>> thank for looking into this. >>> >>> If you could test the patch posted with your error injection systems, >>> that could make this all much simpler to solve. >> The patch posted by Luben will cause double free in some cases. > Yes, I figured this out in the other email and posted the scenario Greg > was asking about. > > But I believe the question still stands if we can do kset_put() > after a *failed* kset_register(), namely if more is being done than > necessary, which is just to free the memory allocated by > kobject_set_name(). The name memory is allocated in kobject_set_name() in caller,  and I think caller free the memory that it allocated is reasonable, it's weird that some callers allocate some memory and use function (kset_register) failed, then it free the memory allocated in callers,  I think use kset_put()/kfree_const(name) in caller seems more reasonable. Thanks, Yang > > Regards, > Luben > . 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 ABEF2C433FE for ; Fri, 21 Oct 2022 10:44:55 +0000 (UTC) Received: from localhost ([::1] helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1olpWI-0001Zr-Mr for qemu-devel@archiver.kernel.org; Fri, 21 Oct 2022 06:44:54 -0400 Received: from [::1] (helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1olomK-0007WD-Vo for qemu-devel@archiver.kernel.org; Fri, 21 Oct 2022 05:57:24 -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 1ololY-00070G-FC for qemu-devel@nongnu.org; Fri, 21 Oct 2022 05:56:56 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ololU-00057y-1i for qemu-devel@nongnu.org; Fri, 21 Oct 2022 05:56:35 -0400 Received: from dggpemm500021.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4Mv09R6B5NzmVJg; Fri, 21 Oct 2022 17:51:39 +0800 (CST) Received: from dggpemm500007.china.huawei.com (7.185.36.183) by dggpemm500021.china.huawei.com (7.185.36.109) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 21 Oct 2022 17:56:21 +0800 Received: from [10.174.178.174] (10.174.178.174) by dggpemm500007.china.huawei.com (7.185.36.183) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 21 Oct 2022 17:56:20 +0800 Subject: Re: [PATCH 00/11] fix memory leak while kset_register() fails To: Luben Tuikov , Greg KH CC: , , , , , , , , , , , , , , , , , , , , References: <20221021022102.2231464-1-yangyingliang@huawei.com> <0591e66f-731a-5f81-fc9d-3a6d80516c65@huawei.com> <78f84006-955f-6209-1cae-024e4f199b97@amd.com> Message-ID: <9ee10048-f3fe-533b-5f00-8e5dd176808e@huawei.com> Date: Fri, 21 Oct 2022 17:56:19 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <78f84006-955f-6209-1cae-024e4f199b97@amd.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Originating-IP: [10.174.178.174] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpemm500007.china.huawei.com (7.185.36.183) X-CFilter-Loop: Reflected Received-SPF: pass client-ip=45.249.212.187; envelope-from=yangyingliang@huawei.com; helo=szxga01-in.huawei.com X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_MED=-2.3, 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" Reply-to: Yang Yingliang From: Yang Yingliang via On 2022/10/21 17:08, Luben Tuikov wrote: > On 2022-10-21 04:59, Yang Yingliang wrote: >> On 2022/10/21 16:36, Greg KH wrote: >>> On Fri, Oct 21, 2022 at 04:24:23PM +0800, Yang Yingliang wrote: >>>> On 2022/10/21 13:37, Greg KH wrote: >>>>> 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://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Flkml%2F0db486eb-6927-927e-3629-958f8f211194%40huawei.com%2FT%2F&data=05%7C01%7Cluben.tuikov%40amd.com%7C74aa9b57192b406ef27408dab3429db4%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C638019395979868103%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=RcK05cXm1J5%2BtYcLO2SMG7k6sjeymQzdBzMCDJSzfdE%3D&reserved=0 >>>>>> The very first discussion on this was here: >>>>>> >>>>>> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.spinics.net%2Flists%2Fdri-devel%2Fmsg368077.html&data=05%7C01%7Cluben.tuikov%40amd.com%7C74aa9b57192b406ef27408dab3429db4%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C638019395979868103%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=sHZ6kfLF8HxrNXV6%2FVjgdH%2BmQM4T3Zv0U%2FAwddT97cE%3D&reserved=0 >>>>>> >>>>>> 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. >>>> I have search the whole tree, the kset used in bus_register() - patch #3, >>>> kset_create_and_add() - patch #4 >>>> __class_register() - patch #5,  fw_cfg_build_symlink() - patch #6 and >>>> amdgpu_discovery.c - patch #10 >>>> is embedded in a larger structure. In these cases, we can not call >>>> kset_put() in error path in kset_register() >>> Yes you can as the kobject in the kset should NOT be controling the >>> lifespan of those larger objects. >>> >>> If it is, please point out the call chain here as I don't think that >>> should be possible. >>> >>> Note all of this is a mess because the kobject name stuff was added much >>> later, after the driver model had been created and running for a while. >>> We missed this error path when adding the dynamic kobject name logic, >>> thank for looking into this. >>> >>> If you could test the patch posted with your error injection systems, >>> that could make this all much simpler to solve. >> The patch posted by Luben will cause double free in some cases. > Yes, I figured this out in the other email and posted the scenario Greg > was asking about. > > But I believe the question still stands if we can do kset_put() > after a *failed* kset_register(), namely if more is being done than > necessary, which is just to free the memory allocated by > kobject_set_name(). The name memory is allocated in kobject_set_name() in caller,  and I think caller free the memory that it allocated is reasonable, it's weird that some callers allocate some memory and use function (kset_register) failed, then it free the memory allocated in callers,  I think use kset_put()/kfree_const(name) in caller seems more reasonable. Thanks, Yang > > Regards, > Luben > . 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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (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 1A1FEC433FE for ; Fri, 21 Oct 2022 13:08:37 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 8325F10E1F1; Fri, 21 Oct 2022 13:08:29 +0000 (UTC) Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by gabe.freedesktop.org (Postfix) with ESMTPS id 4B51510E669 for ; Fri, 21 Oct 2022 09:56:29 +0000 (UTC) Received: from dggpemm500021.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4Mv09R6B5NzmVJg; Fri, 21 Oct 2022 17:51:39 +0800 (CST) Received: from dggpemm500007.china.huawei.com (7.185.36.183) by dggpemm500021.china.huawei.com (7.185.36.109) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 21 Oct 2022 17:56:21 +0800 Received: from [10.174.178.174] (10.174.178.174) by dggpemm500007.china.huawei.com (7.185.36.183) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 21 Oct 2022 17:56:20 +0800 Subject: Re: [PATCH 00/11] fix memory leak while kset_register() fails To: Luben Tuikov , Greg KH References: <20221021022102.2231464-1-yangyingliang@huawei.com> <0591e66f-731a-5f81-fc9d-3a6d80516c65@huawei.com> <78f84006-955f-6209-1cae-024e4f199b97@amd.com> From: Yang Yingliang Message-ID: <9ee10048-f3fe-533b-5f00-8e5dd176808e@huawei.com> Date: Fri, 21 Oct 2022 17:56:19 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <78f84006-955f-6209-1cae-024e4f199b97@amd.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Originating-IP: [10.174.178.174] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpemm500007.china.huawei.com (7.185.36.183) X-CFilter-Loop: Reflected X-Mailman-Approved-At: Fri, 21 Oct 2022 13:08:22 +0000 X-BeenThere: amd-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Discussion list for AMD gfx List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: chao@kernel.org, rafael@kernel.org, qemu-devel@nongnu.org, richard@nod.at, somlo@cmu.edu, mst@redhat.com, linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org, linux-f2fs-devel@lists.sourceforge.net, liushixin2@huawei.com, joseph.qi@linux.alibaba.com, linux-mtd@lists.infradead.org, jlbec@evilplan.org, hsiangkao@linux.alibaba.com, alexander.deucher@amd.com, jaegeuk@kernel.org, akpm@linux-foundation.org, huangjianan@oppo.com, linux-erofs@lists.ozlabs.org, mark@fasheh.com, ocfs2-devel@oss.oracle.com Errors-To: amd-gfx-bounces@lists.freedesktop.org Sender: "amd-gfx" On 2022/10/21 17:08, Luben Tuikov wrote: > On 2022-10-21 04:59, Yang Yingliang wrote: >> On 2022/10/21 16:36, Greg KH wrote: >>> On Fri, Oct 21, 2022 at 04:24:23PM +0800, Yang Yingliang wrote: >>>> On 2022/10/21 13:37, Greg KH wrote: >>>>> 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://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Flkml%2F0db486eb-6927-927e-3629-958f8f211194%40huawei.com%2FT%2F&data=05%7C01%7Cluben.tuikov%40amd.com%7C74aa9b57192b406ef27408dab3429db4%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C638019395979868103%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=RcK05cXm1J5%2BtYcLO2SMG7k6sjeymQzdBzMCDJSzfdE%3D&reserved=0 >>>>>> The very first discussion on this was here: >>>>>> >>>>>> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.spinics.net%2Flists%2Fdri-devel%2Fmsg368077.html&data=05%7C01%7Cluben.tuikov%40amd.com%7C74aa9b57192b406ef27408dab3429db4%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C638019395979868103%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=sHZ6kfLF8HxrNXV6%2FVjgdH%2BmQM4T3Zv0U%2FAwddT97cE%3D&reserved=0 >>>>>> >>>>>> 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. >>>> I have search the whole tree, the kset used in bus_register() - patch #3, >>>> kset_create_and_add() - patch #4 >>>> __class_register() - patch #5,  fw_cfg_build_symlink() - patch #6 and >>>> amdgpu_discovery.c - patch #10 >>>> is embedded in a larger structure. In these cases, we can not call >>>> kset_put() in error path in kset_register() >>> Yes you can as the kobject in the kset should NOT be controling the >>> lifespan of those larger objects. >>> >>> If it is, please point out the call chain here as I don't think that >>> should be possible. >>> >>> Note all of this is a mess because the kobject name stuff was added much >>> later, after the driver model had been created and running for a while. >>> We missed this error path when adding the dynamic kobject name logic, >>> thank for looking into this. >>> >>> If you could test the patch posted with your error injection systems, >>> that could make this all much simpler to solve. >> The patch posted by Luben will cause double free in some cases. > Yes, I figured this out in the other email and posted the scenario Greg > was asking about. > > But I believe the question still stands if we can do kset_put() > after a *failed* kset_register(), namely if more is being done than > necessary, which is just to free the memory allocated by > kobject_set_name(). The name memory is allocated in kobject_set_name() in caller,  and I think caller free the memory that it allocated is reasonable, it's weird that some callers allocate some memory and use function (kset_register) failed, then it free the memory allocated in callers,  I think use kset_put()/kfree_const(name) in caller seems more reasonable. Thanks, Yang > > Regards, > Luben > .