Messages in this thread | | | Date | Mon, 11 Oct 2021 09:29:22 -0700 | From | Roman Gushchin <> | Subject | Re: [PATCH] cgroup: fix memory leak caused by missing cgroup_bpf_offline |
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On Mon, Oct 11, 2021 at 06:21:28PM +0200, Michal Koutny wrote: > Hello. > > On Thu, Oct 07, 2021 at 08:16:03PM +0800, quanyang.wang@windriver.com wrote: > > This is because that root_cgrp->bpf.refcnt.data is allocated by the > > function percpu_ref_init in cgroup_bpf_inherit which is called by > > cgroup_setup_root when mounting, but not freed along with root_cgrp > > when umounting. > > Good catch!
+1
> > > Adding cgroup_bpf_offline which calls percpu_ref_kill to > > cgroup_kill_sb can free root_cgrp->bpf.refcnt.data in umount path. > > That is sensible. > > > Fixes: 2b0d3d3e4fcfb ("percpu_ref: reduce memory footprint of percpu_ref in fast path") > > Why this Fixes:? Is the leak absent before the percpu_ref refactoring?
I agree, the "fixes" tag looks dubious to me.
> I guess the embedded data are free'd together with cgroup. Makes me > wonder why struct cgroup_bpf has a separate percpu_ref counter from > struct cgroup...
This is because a cgroup can stay a long time (sometimes effectively forever) in a dying state, so we want to release bpf structures earlier.
Thanks!
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