Re: [PATCH 1/1] cgroup: rdma: free idle pools during cgroup teardown

[Tao Cui <cui.tao@linux.dev>]

Hi,

在 2026/6/11 02:13, Ren Wei 写道:
> From: Daming Li <d4n.for.sec@gmail.com>
> 
> rdmacg_css_offline() converts each pool to all-max limits so the
> existing reclaim path can free it after the last uncharge. However,
> zero-usage pools are already reclaimable at that point and leaving them
> linked until rdmacg_css_free() lets later device teardown hit a
> use-after-free when free_cg_rpool_locked() deletes cg_node from a freed
> cgroup list head.
> 
> Free zero-usage pools directly from rdmacg_css_offline() while holding
> rdmacg_mutex. This keeps the existing reclaim rule, avoids new lifetime
> states, and ensures a cgroup cannot be freed with reclaimable rdmacg
> pools still attached.
Looks good to me.

One minor note: the offline path skips rpool_has_persistent_state()
and frees idle pools unconditionally. This means peak/event stats are
lost earlier than before (at offline vs. at free). This is fine given
the cgroup is dying, and css_free() cleans up remaining pools anyway.

Reviewed-by: Tao Cui <cuitao@kylinos.cn>

Thanks,
--
Tao