Re: [PATCH] cgroup: fix memory leak caused by missing cgroup_bpf_offline

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Roman Gushchin wrote:
> 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@xxxxxxxxxxxxx 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!

Other than whitespace LGTM.

Acked-by: John Fastabend <john.fastabend@xxxxxxxxx>



[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [IETF Annouce]     [Security]     [Bugtraq]     [Linux OMAP]     [Linux MIPS]     [eCos]     [Asterisk Internet PBX]     [Linux API]     [Monitors]

  Powered by Linux