Re: md_raid: mdX_raid6 looping after sync_action "check" to "idle" transition

[Dragan Stancevic]

On 9/4/23 22:50, Yu Kuai wrote:
> Hi,
>
> 在 2023/08/30 9:36, Yu Kuai 写道:
> > Hi,
> >
> > 在 2023/08/29 4:32, Dragan Stancevic 写道:
> >
> > > Just a followup on 6.1 testing. I tried reproducing this problem for 
> > > 5 days with 6.1.42 kernel without your patches and I was not able to 
> > > reproduce it.
>
> oops, I forgot that you need to backport this patch first to reporduce
> this problem:
>
> https://lore.kernel.org/all/20230529132037.2124527-2-yukuai1@xxxxxxxxxxxxxxx/
>
> The patch fix the deadlock as well, but it introduce some regressions.

Ha, jinx :) I was about to email you that I isolated that change with 
the testing over the weekend that made it more difficult to reproduce in 
6.1 and that the original change must be reverted :)



> Thanks,
> Kuai
>
> > > It seems that 6.1 has some other code that prevents this from happening.
> >
> > I see that there are lots of patches for raid456 between 5.10 and 6.1,
> > however, I remember that I used to reporduce the deadlock after 6.1, and
> > it's true it's not easy to reporduce, see below:
> >
> > https://lore.kernel.org/linux-raid/e9067438-d713-f5f3-0d3d-9e6b0e9efa0e@xxxxxxxxxxxxxxx/
> >
> > My guess is that 6.1 is harder to reporduce than 5.10 due to some
> > changes inside raid456.
> >
> > By the way, raid10 had a similiar deadlock, and can be fixed the same
> > way, so it make sense to backport these patches.
> >
> > https://lore.kernel.org/r/20230529132037.2124527-5-yukuai1@xxxxxxxxxxxxxxx
> >
> > Thanks,
> > Kuai
> >
> >
> > > On 5.10 I can reproduce it within minutes to an hour.
> >
> > .

--
Peace can only come as a natural consequence
of universal enlightenment -Dr. Nikola Tesla