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 C76A4C3062E for ; Thu, 17 Aug 2023 14:50:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352281AbjHQOt7 (ORCPT ); Thu, 17 Aug 2023 10:49:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54354 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1352376AbjHQOty (ORCPT ); Thu, 17 Aug 2023 10:49:54 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 09EC810E for ; Thu, 17 Aug 2023 07:49:53 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id C294C1063; Thu, 17 Aug 2023 07:50:33 -0700 (PDT) Received: from [10.57.34.77] (unknown [10.57.34.77]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4D2613F6C4; Thu, 17 Aug 2023 07:49:51 -0700 (PDT) Message-ID: <8609486c-0807-7ab2-8497-c8d105de4b2b@arm.com> Date: Thu, 17 Aug 2023 15:49:49 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.14.0 Subject: Re: [PATCH 2/2] coresight: core: fix memory leak in dict->fwnode_list To: James Clark , Junhao He , mike.leach@linaro.org, leo.yan@linaro.org Cc: coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linuxarm@huawei.com, jonathan.cameron@huawei.com, yangyicong@huawei.com, prime.zeng@hisilicon.com References: <20230817085937.55590-1-hejunhao3@huawei.com> <20230817085937.55590-3-hejunhao3@huawei.com> <16d7c933-ef2f-682e-742e-641c6a076ac0@arm.com> From: Suzuki K Poulose In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 17/08/2023 15:46, James Clark wrote: > > > On 17/08/2023 15:39, Suzuki K Poulose wrote: >> On 17/08/2023 09:59, Junhao He wrote: >>> There are memory leaks reported by kmemleak: >>> ... >>> unreferenced object 0xffff2020103c3200 (size 256): >>>    comm "insmod", pid 4476, jiffies 4294978252 (age 50072.536s) >>>    hex dump (first 32 bytes): >>>      10 60 40 06 28 20 ff ff 10 c0 59 06 20 20 ff ff  .`@.( ....Y.  .. >>>      10 e0 47 06 28 20 ff ff 10 00 49 06 28 20 ff ff  ..G.( ....I.( .. >>>    backtrace: >>>      [<0000000034ec4724>] __kmem_cache_alloc_node+0x2f8/0x348 >>>      [<0000000057fbc15d>] __kmalloc_node_track_caller+0x5c/0x110 >>>      [<00000055d5e34b>] krealloc+0x8c/0x178 >>>      [<00000000a4635beb>] coresight_alloc_device_name+0x128/0x188 >>> [coresight] >>>      [<00000000a92ddfee>] funnel_cs_ops+0x10/0xfffffffffffedaa0 >>> [coresight_funnel] >>>      [<00000000449e20f8>] dynamic_funnel_ids+0x80/0xfffffffffffed840 >>> [coresight_funnel] >>> ... >>> >>> when remove driver, the golab variables defined by the macro >>> DEFINE_CORESIGHT_DEVLIST will be released, dict->nr_idx and >>> dict->fwnode_list are cleared to 0. The lifetime of the golab >>> variable has ended. So the buffer pointer is lost. >>> >>> Use the callback of devm_add_action_or_reset() to free memory. >> >> Thanks for the report. But please see below: >> >>> >>> Fixes: 0f5f9b6ba9e1 ("coresight: Use platform agnostic names") >>> Signed-off-by: Junhao He >>> --- >>>   drivers/hwtracing/coresight/coresight-core.c | 20 +++++++++++++++++++- >>>   1 file changed, 19 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/hwtracing/coresight/coresight-core.c >>> b/drivers/hwtracing/coresight/coresight-core.c >>> index 9fabe00a40d6..6849faad697d 100644 >>> --- a/drivers/hwtracing/coresight/coresight-core.c >>> +++ b/drivers/hwtracing/coresight/coresight-core.c >>> @@ -1756,6 +1756,20 @@ bool coresight_loses_context_with_cpu(struct >>> device *dev) >>>   } >>>   EXPORT_SYMBOL_GPL(coresight_loses_context_with_cpu); >>>   +void coresight_release_dev_list(void *data) >>> +{ >>> +    struct coresight_dev_list *dict = data; >>> + >>> +    mutex_lock(&coresight_mutex); >>> + >>> +    if (dict->nr_idx) { >>> +        kfree(dict->fwnode_list); >>> +        dict->nr_idx = 0; >>> +    } >>> + >>> +    mutex_unlock(&coresight_mutex); >>> +} >>> + >>>   /* >>>    * coresight_alloc_device_name - Get an index for a given device in the >>>    * device index list specific to a driver. An index is allocated for a >>> @@ -1766,12 +1780,16 @@ >>> EXPORT_SYMBOL_GPL(coresight_loses_context_with_cpu); >>>   char *coresight_alloc_device_name(struct coresight_dev_list *dict, >>>                     struct device *dev) >>>   { >>> -    int idx; >>> +    int idx, ret; >>>       char *name = NULL; >>>       struct fwnode_handle **list; >>>         mutex_lock(&coresight_mutex); >>>   +    ret = devm_add_action_or_reset(dev, coresight_release_dev_list, >>> dict); >>> +    if (ret) >>> +        goto done; >> >> This looks wrong. The devlist should be only released on the "driver" >> unload, not on every device release. The list retains the fwnode to >> assign the same name for a device, if it is re-probed (e.g., due to >> -EPROBE_DEFER error). >> >> Suzuki >> > > I think in that case my suggestion to change it to devm_krealloc_array > might be wrong then. Probably worth putting an explicit comment there in > case someone tries to tidy up all the non devm allocators to devm ones. > > But how do you release a single device without releasing the whole driver? You could unbind a device from the driver and that will make another driver probe it. I know it works for PCI/platform with VFIO. Suzuki > > James