Messages in this thread | | | From | KOSAKI Motohiro <> | Subject | Re: [PATCH] cpuset: current_cpuset_is_being_rebound() need rcu lock | Date | Fri, 12 Mar 2010 09:03:03 +0900 (JST) |
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> On Thu, Mar 11, 2010 at 02:46:15PM +0900, KOSAKI Motohiro wrote: > > rcu lockdep detected cpuset have wrong rcu usage. > > the fixing is trivial. but I wonder why don't cpuset_being_rebound assignment > > and read need a memory barrier pairing? > > The fix is in -tip, commit 99ee4ca746dda71326db7645463b4075ac1d665c. > > This is an initialization-time use of rcu_dereference(), so no other > task has a reference to this data. Hence it is constant. Other uses > of this code operate on shared data structures, which might change at > any time.
thanks. I haven't notice such commit.
I think you are talking about task_cs(current) accessing and you are right in such point. but I'm talking cpuset_being_rebound global variable.
update_tasks_nodemask() has following code
static void update_tasks_nodemask(struct cpuset *cs, const nodemask_t *oldmem, struct ptr_heap *heap) { cpuset_being_rebound = cs; /* start transaction */ cgroup_scan_tasks(&scan); cpuset_being_rebound = NULL; /* end transaction */ }
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