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From:   Naresh Kamboju <naresh.kamboju@linaro.org>
Date:   Wed, 14 Jul 2021 19:29:26 +0530
Message-ID: <CA+G9fYtWkOLVVKB0xYfAXWS57G1C2xV-Zbtp5i4dAJDJqwLQhg@mail.gmail.com>
Subject: Re: [PATCH 5.13 000/800] 5.13.2-rc1 review
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Holger Kiehl <Holger.Kiehl@dwd.de>, Jan Kara <jack@suse.cz>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Guenter Roeck <linux@roeck-us.net>,
        Shuah Khan <shuah@kernel.org>, patches@kernelci.org,
        lkft-triage@lists.linaro.org, Pavel Machek <pavel@denx.de>,
        Jon Hunter <jonathanh@nvidia.com>,
        Florian Fainelli <f.fainelli@gmail.com>,
        linux-stable <stable@vger.kernel.org>,
        Paolo Valente <paolo.valente@linaro.org>,
        Jens Axboe <axboe@kernel.dk>
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On Wed, 14 Jul 2021 at 19:22, Naresh Kamboju <naresh.kamboju@linaro.org> wrote:
>
> On Wed, 14 Jul 2021 at 19:01, Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> >

<trim>

> My two cents,
> While running ssuite long running stress testing we have noticed deadlock.
>
> > So if you drop that, all works well?  I'll go drop that from the queues
> > now.
>
> Let me drop that patch and test it again.
>
> Crash log,
>
> [ 1957.278399] ============================================
> [ 1957.283717] WARNING: possible recursive locking detected
> [ 1957.289031] 5.13.2-rc1 #1 Not tainted
> [ 1957.292703] --------------------------------------------
> [ 1957.298016] kworker/u8:7/236 is trying to acquire lock:
> [ 1957.303241] ffff8cc203f92c38 (&bfqd->lock){-.-.}-{2:2}, at:
> bfq_finish_requeue_request+0x55/0x500 [bfq]
> [ 1957.312643]
> [ 1957.312643] but task is already holding lock:
> [ 1957.318467] ffff8cc203f92c38 (&bfqd->lock){-.-.}-{2:2}, at:
> bfq_insert_requests+0x81/0x1750 [bfq]
> [ 1957.327334]
> [ 1957.327334] other info that might help us debug this:
> [ 1957.333852]  Possible unsafe locking scenario:
> [ 1957.333852]
> [ 1957.339762]        CPU0
> [ 1957.342206]        ----
> [ 1957.344651]   lock(&bfqd->lock);
> [ 1957.347873]   lock(&bfqd->lock);
> [ 1957.351097]
> [ 1957.351097]  *** DEADLOCK ***
> [ 1957.351097]

Also noticed on stable-rc 5.12.17-rc1.

> Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
>
> ref:
> https://lkft.validation.linaro.org/scheduler/job/3058868#L2922

ref:
https://lkft.validation.linaro.org/scheduler/job/3058423#L3125


- Naresh