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 /* found lock contention or "pc" is obsolete.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,
-kame
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