Re: [syzbot] possible deadlock in loop_add

[Desmond Cheong Zhi Xi]

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.

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.

Best wishes,
Desmond