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From: Desmond Cheong Zhi Xi <>
To: Miquel Raynal <>,
	Hillf Danton <>
Cc: Christoph Hellwig <>,
	syzbot <>,,,,
Subject: Re: [syzbot] possible deadlock in loop_add
Date: Sat, 17 Jul 2021 17:41:03 +0800	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <20210716010028.4218b0de@xps13>

On 16/7/21 7:00 am, Miquel Raynal wrote:
> Hello,
> Desmond Cheong Zhi Xi <> wrote on Mon, 12 Jul
> 2021 16:29:16 +0800:
>> On 12/7/21 1:27 pm, Christoph Hellwig wrote:
>>> On Sat, Jul 10, 2021 at 09:16:38PM +0800, Hillf Danton wrote:
>>>> To break the lock chain, un/register blkdev without mtd_table_mutex held.
>>> Yes, Desmond Cheong Zhi Xi sent pretty much the same patch on June 18th
>>> (mtd: break circular locks in register_mtd_blktrans), but it did not get
>>> picked up.
>> I believe Miquèl was waiting for -rc1 to apply it.
> Indeed, I already applied it but did not advertise yet.

Thanks Miquèl!

>> But taking a closer look, although the fix for the register path is the same, Hillf Danton's proposed patch additionally avoids inverting the lock hierarchy on the unregister path. So I believe this new patch should be more robust.
> We can definitely do this in two steps if you want.

Sounds good, I'll prepare a patch with Hillf's suggestion for the 
unregister path.

> Thanks,
> Miquèl

      reply	other threads:[~2021-07-17  9:41 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-10 11:01 [syzbot] possible deadlock in loop_add syzbot
     [not found] ` <>
2021-07-12  5:27   ` Christoph Hellwig
2021-07-12  8:29     ` Desmond Cheong Zhi Xi
2021-07-15 23:00       ` Miquel Raynal
2021-07-17  9:41         ` Desmond Cheong Zhi Xi [this message]

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