Hi Ming,

On 10/20/21 10:17 AM, Ming Lei wrote:

On Tue, Oct 19, 2021 at 07:10:26PM +0200, Michal Koutný wrote:

quoted

Hi.

On Tue, Oct 19, 2021 at 06:41:14PM +0800, Quanyang Wang [off-list ref] wrote:

quoted

So I add 2 "Fixes tags" here to indicate that 2 commits introduce two
different issues.

AFAIU, both the changes are needed to cause the leak, a single patch
alone won't cause the issue. Is that correct? (Perhaps not as I realize,
see below.)

But on second thought, the problem is the missing percpu_ref_exit() in
the (root) cgroup release path and percpu counter would allocate the
percpu_count_ptr anyway, so 4bfc0bb2c60e is only making the leak more
visible. Is this correct?

I agree the commit 2b0d3d3e4fcf ("percpu_ref: reduce memory footprint of
percpu_ref in fast path") alone did nothing wrong.

If only precpu_ref data is leaked, it is fine to add "Fixes: 2b0d3d3e4fcf",
I thought cgroup_bpf_release() needs to release more for root cgroup, but
looks not true.

For now, I can only observe that precpu_ref data is leaked when running 
ltp testsuite.
Thanks,
Quanyang

Thanks,
Ming