Re: [PATCH cgroup] https://github.com/raspberrypi/linux/issues/6631

[David Reaver]

Umar Pathan <cynexium@xxxxxxxxx> writes:

> The existing freezer propagation logic improperly reduces
> nr_frozen_descendants by an increasing 'desc' counter during unfreeze,
> leading to:
> - Premature parent cgroup unfreezing
> - Negative descendant counts
> - Broken hierarchy state consistency
>
> Scenario demonstrating the bug:
> 1. Create hierarchy A->B->C
> 2. Freeze C (A/B freeze via propagation)
> 3. Freeze A->D (separate branch)
> 4. Unfreeze C -> A incorrectly unfreezes despite frozen D
>
> Fixes: 711f763 ("freezer,cgroup: add freezer.stats subsystem")
> Signed-off-by: Umar cynexium@xxxxxxxxx
> ---
>  kernel/cgroup/freezer.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/kernel/cgroup/freezer.c b/kernel/cgroup/freezer.c
> index e9c15fbe5d9b..d384df2f53c2 100644
> --- a/kernel/cgroup/freezer.c
> +++ b/kernel/cgroup/freezer.c
> @@ -304,6 +304,7 @@ void cgroup_freeze(struct cgroup *cgrp, bool freeze)
>  			 */
>  			if (dsct->freezer.e_freeze > 0)
>  				continue;
> +
>  			WARN_ON_ONCE(dsct->freezer.e_freeze < 0);
>  		}

Hey Umar,

I dug around Github and I think I found the patch you intended to submit
https://github.com/raspberrypi/linux/pull/6632/commits/711f76376ae7e11f48a1c22a4a04828a24d6a87a

Unfortunately, your email only contains the inverse of your PR's
whitespace change removing a line in freezer.c, not the rest of the
patch. Did you perhaps revert that whitespace change in a new commit and
accidentally only submit that commit instead of the whole change?

Thanks,
David Reaver