From: Jens Axboe <axboe@kernel.dk>
To: Bart Van Assche <bvanassche@acm.org>
Cc: linux-block@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
Damien Le Moal <damien.lemoal@wdc.com>,
Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Subject: Re: [PATCH] null_blk: Fix a NULL pointer dereference
Date: Thu, 23 Sep 2021 11:55:31 -0600 [thread overview]
Message-ID: <fc3299cf-1603-fcd9-6287-1424586cb479@kernel.dk> (raw)
In-Reply-To: <83d45e6b-6bd5-8e59-d0bf-6d86b18a81f4@acm.org>
On 9/23/21 11:51 AM, Bart Van Assche wrote:
> On 9/23/21 9:39 AM, Jens Axboe wrote:
>> On 9/23/21 10:22 AM, Bart Van Assche wrote:
>>> On 9/23/21 9:04 AM, Jens Axboe wrote:
>>>> What options are you loading null_blk with?
>>>
>>> The issues I reported are the result of running test blk/010 from the
>>> blktests suite. That test loads the null_blk kernel module twice:
>>>
>>> _init_null_blk queue_mode=2 submit_queues=16 nr_devices=32
>>> [ ... ]
>>> _exit_null_blk
>>> _init_null_blk queue_mode=2 submit_queues=16 nr_devices=32 shared_tags=1
>>> [ ... ]
>>> _exit_null_blk
>>>
>>> Please let me know if you need more information.
>>
>> Tried both that and running block/010, didn't trigger anything for me.
>> Odd...
>
> Hi Jens,
>
> I took another look at the kernel logs from yesterday of the VM that I use
> for testing. In that kernel log I found the following:
> * Without any changes on top of the for-next branch of
> git://git.kernel.dk/linux-block (commit 4129031563d0 ("Merge branch
> 'for-5.16/io_uring' into for-next"), test block/010 triggers the oops
> reported at the start of this email thread.
> * With the patch at the start of this email thread applied, the first test
> that triggers a kernel oops is block/020 (blk_mq_free_rqs+0x1f4).
>
> This morning I rebuilt the block for-next kernel with and without my
> null_blk patch applied. I was able to reproduce what I observed yesterday.
> Test block/020 passes with if commit 5f7acddf706c ("null_blk: poll queue
> support") is reverted. This is why I wrote that my patch does not seem to
> be sufficient to fix commit 5f7acddf706c.
Ah ok, so it's block/020, not block/010 for the later one. I'll take a
look.
--
Jens Axboe
next prev parent reply other threads:[~2021-09-23 17:55 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-22 17:50 [PATCH] null_blk: Fix a NULL pointer dereference Bart Van Assche
2021-09-22 17:54 ` Jens Axboe
2021-09-22 18:03 ` Bart Van Assche
2021-09-22 18:26 ` Bart Van Assche
2021-09-23 16:04 ` Jens Axboe
2021-09-23 16:22 ` Bart Van Assche
2021-09-23 16:39 ` Jens Axboe
2021-09-23 17:51 ` Bart Van Assche
2021-09-23 17:55 ` Jens Axboe [this message]
2021-09-23 18:53 ` Jens Axboe
2021-09-23 19:16 ` Bart Van Assche
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