On Fri, Oct 22, 2021 at 4:56 AM Quanyang Wang
[off-list ref] wrote:

quoted

quoted

Fixes: 2b0d3d3e4fcf ("percpu_ref: reduce memory footprint of percpu_ref in fast path")
Fixes: 4bfc0bb2c60e ("bpf: decouple the lifetime of cgroup_bpf from cgroup itself")
Signed-off-by: Quanyang Wang <redacted>
---
V1 ---> V2:
1. As per Daniel's suggestion, add description to commit msg about the
balance of cgroup's refcount in cgroup_bpf_offline.
2. As per Michal's suggestion, add tag "Fixes: 4bfc0bb2c60e" and add
description about it.
3. Fix indentation on the percpu_ref_is_dying line.

Acked-by: Roman Gushchin <redacted>

The fix looks correct, two fixes tag are fine too, if only it won't
confuse scripts picking up patches for stable backports.

In fact, it's a very cold path, which is arguably never hit in the real
life. On cgroup v2 it's not an issue. I'm not sure we need a stable
backport at all, only if it creates a noise for some automation tests.

Quanyang, out of curiosity, how did you find it?

I ran ltp testsuite to find this.

./runltp -f controllers -s cgroup

Thanks,
Quanyang

quoted

Anyway, thanks for catching and fixing it!

Applied to bpf tree. Thanks everyone!