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Message-ID: <6e21f7d3-49d0-eda7-7a89-0f8ac69596a4@samsung.com>
Date:   Fri, 29 Apr 2022 16:51:02 +0200
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Subject: Re: [PATCH v7 12/12] rpmsg: Fix kfree() of static memory on setting
 driver_override
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To:     Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>
Cc:     Stuart Yoder <stuyoder@gmail.com>,
        "K. Y. Srinivasan" <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        Wei Liu <wei.liu@kernel.org>, Dexuan Cui <decui@microsoft.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Mathieu Poirier <mathieu.poirier@linaro.org>,
        Vineeth Vijayan <vneethv@linux.ibm.com>,
        Peter Oberparleiter <oberpar@linux.ibm.com>,
        Heiko Carstens <hca@linux.ibm.com>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Alexander Gordeev <agordeev@linux.ibm.com>,
        Christian Borntraeger <borntraeger@linux.ibm.com>,
        Sven Schnelle <svens@linux.ibm.com>,
        Andy Gross <agross@kernel.org>, linux-kernel@vger.kernel.org,
        linux-clk@vger.kernel.org, NXP Linux Team <linux-imx@nxp.com>,
        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 <torvalds@linux-foundation.org>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        Andy Shevchenko <andy.shevchenko@gmail.com>
From:   Marek Szyprowski <m.szyprowski@samsung.com>
In-Reply-To: <75b94ccd-b739-2164-bc4a-20025356cc34@linaro.org>
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References: <20220419113435.246203-1-krzysztof.kozlowski@linaro.org>
        <20220419113435.246203-13-krzysztof.kozlowski@linaro.org>
        <CGME20220429122942eucas1p1820d0cd17a871d4953bac2b3de1dcdd9@eucas1p1.samsung.com>
        <870885de-33f3-e0ba-4d56-71c3c993ac87@samsung.com>
        <75b94ccd-b739-2164-bc4a-20025356cc34@linaro.org>
Precedence: bulk

On 29.04.2022 16:16, Krzysztof Kozlowski wrote:
> On 29/04/2022 14:29, Marek Szyprowski wrote:
>> 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 <krzysztof.kozlowski@linaro.org>
>>> Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
>> 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): [<ffff80000919053c>]
>> _raw_spin_unlock_irqrestore+0x98/0x9c
>> hardirqs last disabled at (3598): [<ffff800009190ba4>]
>> _raw_spin_lock_irqsave+0xc0/0xcc
>> softirqs last  enabled at (3554): [<ffff800008010470>] _stext+0x470/0x5e8
>> softirqs last disabled at (3549): [<ffff8000080a4514>]
>> __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/

This doesn't help, the issue is still reported.

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland