Re: [PATCH v8 11/12] zram: fix crashes with cpu hotplug multistate

Luis Chamberlain
2021-10-15T17:31:45Z

On Fri, Oct 15, 2021 at 04:36:11PM +0800, Ming Lei wrote:
> On Thu, Oct 14, 2021 at 05:22:40PM -0700, Luis Chamberlain wrote:
> > On Fri, Oct 15, 2021 at 07:52:04AM +0800, Ming Lei wrote:
> ...
> > >
> > > We need to understand the exact reason why there is still cpuhp node
> > > left, can you share us the exact steps for reproducing the issue?
> > > Otherwise we may have to trace and narrow down the reason.
> >
> > See my commit log for my own fix for this issue.
>
> OK, thanks!
>
> I can reproduce the issue, and the reason is that reset_store fails
> zram_remove() when unloading module, then the warning is caused.
>
> The top 3 patches in the following tree can fix the issue:
>
> https://github.com/ming1/linux/commits/my_v5.15-blk-dev

Thanks for trying an alternative fix! A crash stops yes, however this
also ends up leaving the driver in an unrecoverable state after a few
tries. Ie, you CTRL-C the scripts and try again over and over again and
the driver ends up in a situation where it just says:

zram: Can't change algorithm for initialized device

And the zram module can't be removed at that point.

Luis