Messages in this thread | | | Date | Thu, 20 Dec 2007 19:21:19 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: [PATCH] Memory controller use rcu_read_lock() in mem_cgroup_cache_charge() |
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On Thu, 20 Dec 2007 14:31:52 +0530 Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
> > > Hugh Dickins noticed that we were using rcu_dereference() without > rcu_read_lock() in the cache charging routine. The patch below fixes > this problem > > Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> > --- > > mm/memcontrol.c | 10 +++++++--- > 1 file changed, 7 insertions(+), 3 deletions(-) > > diff -puN mm/memcontrol.c~memory-controller-use-rcu-lead-lock mm/memcontrol.c > --- linux-2.6.24-rc5/mm/memcontrol.c~memory-controller-use-rcu-lead-lock 2007-12-19 11:52:44.000000000 +0530 > +++ linux-2.6.24-rc5-balbir/mm/memcontrol.c 2007-12-20 14:01:45.000000000 +0530 > @@ -717,16 +717,20 @@ int mem_cgroup_charge(struct page *page, > int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm, > gfp_t gfp_mask) > { > + int ret = 0; > struct mem_cgroup *mem; > if (!mm) > mm = &init_mm; > > + rcu_read_lock(); > mem = rcu_dereference(mm->mem_cgroup); > + css_get(&mem->css); > + rcu_read_unlock(); > if (mem->control_type == MEM_CGROUP_TYPE_ALL) > - return mem_cgroup_charge_common(page, mm, gfp_mask, > + ret = mem_cgroup_charge_common(page, mm, gfp_mask, > MEM_CGROUP_CHARGE_TYPE_CACHE); > - else > - return 0; > + css_put(&mem->css); > + return ret; > } > > /* > _ Seems reasonable to me. Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Thanks, -Kame
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