Re: dm-verity requires WQ_UNBOUND with mxs-dcp

[Eric Biggers <ebiggers@kernel.org>]

On Tue, May 28, 2024 at 10:58:33AM +0200, Sven wrote:
> Hi,
> 
> I'm seeing a problem using dm-verity with the sha256-dcp driver (mxs-dcp).
> Specifically, I'm seeing corruption errors a la
> 
> device-mapper: verity: 179:2: metadata block 76823 is corrupted
> 
> This is a regression that has started to appear with commit
> 
> c25da5b7baf1d dm verity: stop using WQ_UNBOUND for verify_wq
> 
> Reverting that commit while keeping an identical rootfs fixes my issue and I
> don't get any warnings anymore. I'm using an i.MX6ULL SoC which only has one
> CPU core so I don't really understand how WQ_UNBOUND can have an affect
> here. However, there might be side effects that I'm not aware of.
> 
> It might be worth noting that I'm using the dm-verity device as my root
> device without initramfs. I'm seeing this on both v6.6.23 and today's master
> (v6.10-rc1-13-g2bfcfd584ff5c).
> 
> Does anyone have ideas, how WQ_UNBOUND could be required here?
> 

Does this happen with software SHA-256, or is it specific to the sha256-dcp
driver?  Does this driver pass all the crypto self-tests?

- Eric