Messages in this thread | | | Date | Fri, 16 May 2014 11:19:24 -0600 | From | Stephen Warren <> | Subject | Re: [PATCH v2 cgroup/for-3.16] cgroup: introduce CSS_NO_REF and skip refcnting on normal root csses |
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On 05/16/2014 11:09 AM, Tejun Heo wrote: > 9395a4500404 ("cgroup: enable refcnting for root csses") enabled > reference counting for root csses (cgroup_subsys_states) so that > cgroup's self csses can be used to manage the lifetime of the > containing cgroups. > > Unfortunately, this change was incorrect. During early init, > cgrp_dfl_root self css refcnt is used. percpu_ref can't initialized > during early init and its initialization is deferred till > cgroup_init() time. This means that cpu was using percpu_ref which > wasn't properly initialized. Due to the way percpu variables are laid > out on x86, this didn't blow up immediately on x86 but ended up > incrementing and decrementing the percpu variable at offset zero, > whatever it may be; however, on other archs, this caused fault and > early boot failure. > > As cgroup self csses for root cgroups of non-dfl hierarchies need > working refcounting, we can't revert 9395a4500404. This patch adds > CSS_NO_REF which explicitly inhibits reference counting on the css and > sets it on all normal (non-self) csses and cgroup_dfl_root self css. > > v2: cgrp_dfl_root.self is the offending one. Set the flag on it. > > Signed-off-by: Tejun Heo <tj@kernel.org> > Reported-by: Stephen Warren <swarren@wwwdotorg.org> > Fixes: 9395a4500404 ("cgroup: enable refcnting for root csses") > --- > Hello, > > Can you try this one instead?
Yes, this one works great, thanks. Tested-by: Stephen Warren <swarren@nvidia.com>
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