linux-kernel - Re: Observation of a memory leak with commit e98e49b2bbf7 ("io

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Message-ID: <5f2be3fe-7a16-6559-7d40-575c6e29e443@gmail.com>
Date:   Sun, 9 Jan 2022 00:57:15 +0000
From:   Pavel Begunkov <asml.silence@...il.com>
To:     Lukas Bulwahn <lukas.bulwahn@...il.com>,
        Jens Axboe <axboe@...nel.dk>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        io-uring@...r.kernel.org
Subject: Re: Observation of a memory leak with commit e98e49b2bbf7 ("io_uring:
 extend task put optimisations")

On 1/7/22 16:22, Pavel Begunkov wrote:
> On 1/7/22 15:00, Lukas Bulwahn wrote:
>> Dear Pavel, dear Jens,
>>
>> In our syzkaller instance running on linux-next,
>> https://elisa-builder-00.iol.unh.edu/syzkaller-next/, we have been
>> observing a memory leak in copy_process for quite some time.
>>
>> It is reproducible on v5.15-rc1, v5.15, v5.16-rc8 and next-20220106:
>>
>> https://elisa-builder-00.iol.unh.edu/syzkaller-next/crash?id=1169da08a3e72457301987b70bcce62f0f49bdbb
>>
>> So, it is in mainline, was released and has not been fixed in linux-next yet.
>>
>> As syzkaller also provides a reproducer, we bisected this memory leak
>> to be introduced with commit e98e49b2bbf7 ("io_uring: extend task put
>> optimisations").
>>
>> Could you please have a look how your commit introduces this memory
>> leak? We will gladly support testing your fix in case help is needed.
> 
> Thanks for letting know
> I think I know what it is, will get back later.

https://lore.kernel.org/io-uring/69f226b35fbdb996ab799a8bbc1c06bf634ccec1.1641688805.git.asml.silence@gmail.com

Should fix it, tested with the repro

-- 
Pavel Begunkov