On Fri, Apr 27, 2012 at 5:25 PM, Hiroyuki Kamezawa
<kamezawa.hiroyuki@xxxxxxxxx> wrote:
> On Sat, Apr 28, 2012 at 6:28 AM, Ying Han <yinghan@xxxxxxxxxx> wrote:
>> On Thu, Apr 26, 2012 at 11:06 PM, KAMEZAWA Hiroyuki
>> <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
>>> When force_empty() called by ->pre_destroy(), no memory reclaim happens
>>> and it doesn't take very long time which requires signal_pending() check.
>>> And if we return -EINTR from pre_destroy(), cgroup.c show warning.
>>>
>>> This patch removes signal check in force_empty(). By this, ->pre_destroy()
>>> returns success always.
>>>
>>> Note: check for 'cgroup is empty' remains for force_empty interface.
>>>
>>> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
>>> ---
>>> mm/hugetlb.c | 10 +---------
>>> mm/memcontrol.c | 14 +++++---------
>>> 2 files changed, 6 insertions(+), 18 deletions(-)
>>>
>>> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
>>> index 4dd6b39..770f1642 100644
>>> --- a/mm/hugetlb.c
>>> +++ b/mm/hugetlb.c
>>> @@ -1922,20 +1922,12 @@ int hugetlb_force_memcg_empty(struct cgroup *cgroup)
>>> int ret = 0, idx = 0;
>>>
>>> do {
>>> + /* see memcontrol.c::mem_cgroup_force_empty() */
>>> if (cgroup_task_count(cgroup)
>>> || !list_empty(&cgroup->children)) {
>>> ret = -EBUSY;
>>> goto out;
>>> }
>>> - /*
>>> - * If the task doing the cgroup_rmdir got a signal
>>> - * we don't really need to loop till the hugetlb resource
>>> - * usage become zero.
>>> - */
>>> - if (signal_pending(current)) {
>>> - ret = -EINTR;
>>> - goto out;
>>> - }
>>> for_each_hstate(h) {
>>> spin_lock(&hugetlb_lock);
>>> list_for_each_entry(page, &h->hugepage_activelist, lru) {
>>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>>> index 2715223..ee350c5 100644
>>> --- a/mm/memcontrol.c
>>> +++ b/mm/memcontrol.c
>>> @@ -3852,8 +3852,6 @@ static int mem_cgroup_force_empty_list(struct mem_cgroup *memcg,
>>> pc = lookup_page_cgroup(page);
>>>
>>> ret = mem_cgroup_move_parent(page, pc, memcg, GFP_KERNEL);
>>> - if (ret == -ENOMEM || ret == -EINTR)
>>> - break;
>>>
>>> if (ret == -EBUSY || ret == -EINVAL) {
>>> /* found lock contention or "pc" is obsolete. */
>>> @@ -3863,7 +3861,7 @@ static int mem_cgroup_force_empty_list(struct mem_cgroup *memcg,
>>> busy = NULL;
>>> }
>>>
>>> - if (!ret && !list_empty(list))
>>> + if (!loop)
>>
>> This looks a bit strange to me... why we make the change ?
>>
> Ah, I should this move to an independet patch.
> Because we don't have -ENOMEM path to exit loop, the return value of
> this function
> is
> 0 (if loop !=0 this means lru is empty under the lru lock )
> -EBUSY (if loop== 0)
>
> I'll move this part out as an independent clean up patch
Thanks ~
--Ying
> thanks,
> -kame
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