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[188.155.176.92]) by smtp.gmail.com with ESMTPSA id j12-20020a50ed0c000000b0042617ba63d4sm2982642eds.94.2022.04.29.07.16.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 29 Apr 2022 07:16:34 -0700 (PDT) Message-ID: <75b94ccd-b739-2164-bc4a-20025356cc34@linaro.org> Date: Fri, 29 Apr 2022 16:16:32 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [PATCH v7 12/12] rpmsg: Fix kfree() of static memory on setting driver_override Content-Language: en-US To: Marek Szyprowski , Greg Kroah-Hartman , "Rafael J. Wysocki" Cc: Stuart Yoder , "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , Wei Liu , Dexuan Cui , Bjorn Helgaas , Bjorn Andersson , Mathieu Poirier , Vineeth Vijayan , Peter Oberparleiter , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Andy Gross , linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org, NXP Linux Team , linux-arm-kernel@lists.infradead.org, linux-hyperv@vger.kernel.org, linux-pci@vger.kernel.org, linux-remoteproc@vger.kernel.org, linux-s390@vger.kernel.org, linux-arm-msm@vger.kernel.org, alsa-devel@alsa-project.org, linux-spi@vger.kernel.org, virtualization@lists.linux-foundation.org, Linus Torvalds , Rasmus Villemoes , Andy Shevchenko References: <20220419113435.246203-1-krzysztof.kozlowski@linaro.org> <20220419113435.246203-13-krzysztof.kozlowski@linaro.org> <870885de-33f3-e0ba-4d56-71c3c993ac87@samsung.com> From: Krzysztof Kozlowski In-Reply-To: <870885de-33f3-e0ba-4d56-71c3c993ac87@samsung.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 29/04/2022 14:29, Marek Szyprowski wrote: > Hi Krzysztof, > > On 19.04.2022 13:34, Krzysztof Kozlowski wrote: >> The driver_override field from platform driver should not be initialized >> from static memory (string literal) because the core later kfree() it, >> for example when driver_override is set via sysfs. >> >> Use dedicated helper to set driver_override properly. >> >> Fixes: 950a7388f02b ("rpmsg: Turn name service into a stand alone driver") >> Fixes: c0cdc19f84a4 ("rpmsg: Driver for user space endpoint interface") >> Signed-off-by: Krzysztof Kozlowski >> Reviewed-by: Bjorn Andersson > > This patch landed recently in linux-next as commit 42cd402b8fd4 ("rpmsg: > Fix kfree() of static memory on setting driver_override"). In my tests I > found that it triggers the following issue during boot of the > DragonBoard410c SBC (arch/arm64/boot/dts/qcom/apq8016-sbc.dtb): > > ------------[ cut here ]------------ > DEBUG_LOCKS_WARN_ON(lock->magic != lock) > WARNING: CPU: 1 PID: 8 at kernel/locking/mutex.c:582 > __mutex_lock+0x1ec/0x430 > Modules linked in: > CPU: 1 PID: 8 Comm: kworker/u8:0 Not tainted 5.18.0-rc4-next-20220429 #11815 > Hardware name: Qualcomm Technologies, Inc. APQ 8016 SBC (DT) > Workqueue: events_unbound deferred_probe_work_func > pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) > pc : __mutex_lock+0x1ec/0x430 > lr : __mutex_lock+0x1ec/0x430 > .. > Call trace: >  __mutex_lock+0x1ec/0x430 >  mutex_lock_nested+0x38/0x64 >  driver_set_override+0x124/0x150 >  qcom_smd_register_edge+0x2a8/0x4ec >  qcom_smd_probe+0x54/0x80 >  platform_probe+0x68/0xe0 >  really_probe.part.0+0x9c/0x29c >  __driver_probe_device+0x98/0x144 >  driver_probe_device+0xac/0x14c >  __device_attach_driver+0xb8/0x120 >  bus_for_each_drv+0x78/0xd0 >  __device_attach+0xd8/0x180 >  device_initial_probe+0x14/0x20 >  bus_probe_device+0x9c/0xa4 >  deferred_probe_work_func+0x88/0xc4 >  process_one_work+0x288/0x6bc >  worker_thread+0x248/0x450 >  kthread+0x118/0x11c >  ret_from_fork+0x10/0x20 > irq event stamp: 3599 > hardirqs last  enabled at (3599): [] > _raw_spin_unlock_irqrestore+0x98/0x9c > hardirqs last disabled at (3598): [] > _raw_spin_lock_irqsave+0xc0/0xcc > softirqs last  enabled at (3554): [] _stext+0x470/0x5e8 > softirqs last disabled at (3549): [] > __irq_exit_rcu+0x180/0x1ac > ---[ end trace 0000000000000000 ]--- > > I don't see any direct relation between the $subject and the above log, > but reverting the $subject on top of linux next-20220429 hides/fixes it. > Maybe there is a kind of memory trashing somewhere there and your change > only revealed it? Thanks for the report. I think the error path of my patch is wrong - I should not kfree(rpdev->driver_override) from the rpmsg code. That's the only thing I see now... Could you test following patch and tell if it helps? https://pastebin.ubuntu.com/p/rp3q9Z5fXj/ ----- diff --git a/drivers/rpmsg/rpmsg_internal.h b/drivers/rpmsg/rpmsg_internal.h index 3e81642238d2..1e2ad944e2ec 100644 --- a/drivers/rpmsg/rpmsg_internal.h +++ b/drivers/rpmsg/rpmsg_internal.h @@ -102,11 +102,7 @@ static inline int rpmsg_ctrldev_register_device(struct rpmsg_device *rpdev) if (ret) return ret; - ret = rpmsg_register_device(rpdev); - if (ret) - kfree(rpdev->driver_override); - - return ret; + return rpmsg_register_device(rpdev); } #endif diff --git a/drivers/rpmsg/rpmsg_ns.c b/drivers/rpmsg/rpmsg_ns.c index 8eb8f328237e..f26078467899 100644 --- a/drivers/rpmsg/rpmsg_ns.c +++ b/drivers/rpmsg/rpmsg_ns.c @@ -31,11 +31,7 @@ int rpmsg_ns_register_device(struct rpmsg_device *rpdev) rpdev->src = RPMSG_NS_ADDR; rpdev->dst = RPMSG_NS_ADDR; - ret = rpmsg_register_device(rpdev); - if (ret) - kfree(rpdev->driver_override); - - return ret; + return rpmsg_register_device(rpdev); } EXPORT_SYMBOL(rpmsg_ns_register_device);