Michal Hocko <mhocko@xxxxxxx> writes:
> On Wed 13-06-12 15:57:30, Aneesh Kumar K.V wrote:
>> From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
>>
>> This patchset add the charge and uncharge routines for hugetlb cgroup.
>> We do cgroup charging in page alloc and uncharge in compound page
>> destructor. Assigning page's hugetlb cgroup is protected by hugetlb_lock.
>>
>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
>
> Reviewed-by: Michal Hocko <mhocko@xxxxxxx>
>
> One minor comment
> [...]
>> +void hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages,
>> + struct hugetlb_cgroup *h_cg,
>> + struct page *page)
>> +{
>> + if (hugetlb_cgroup_disabled() || !h_cg)
>> + return;
>> +
>> + spin_lock(&hugetlb_lock);
>> + set_hugetlb_cgroup(page, h_cg);
>> + spin_unlock(&hugetlb_lock);
>> + return;
>> +}
>
> I guess we can remove the lock here because nobody can see the page yet,
> right?
>
We need that to make sure when we remove cgroup we find correct page
hugetlb cgroup values. But i guess we have a bug here. How about the
below ?
NOTE: We also need another patch to update active list during soft
offline. I will send that in reply.
commit e4c3fd3cc0f0faa30ea283cb48ba478a5c0d3e74
Author: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Date: Fri Jun 15 14:42:27 2012 +0530
hugetlb/cgroup: Assign the page hugetlb cgroup when we move the page to active list.
page's hugetlb cgroup assign and moving to active list should happen with
hugetlb_lock held. Otherwise when we remove the hugetlb cgroup we would
iterate the active list and will find page with NULL hugetlb cgroup values.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index ee4da3b..b90dfb4 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1146,9 +1146,12 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma,
}
spin_lock(&hugetlb_lock);
page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve);
- spin_unlock(&hugetlb_lock);
-
- if (!page) {
+ if (page) {
+ /* update page cgroup details */
+ hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, page);
+ spin_unlock(&hugetlb_lock);
+ } else {
+ spin_unlock(&hugetlb_lock);
page = alloc_buddy_huge_page(h, NUMA_NO_NODE);
if (!page) {
hugetlb_cgroup_uncharge_cgroup(idx,
@@ -1159,14 +1162,13 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma,
}
spin_lock(&hugetlb_lock);
list_move(&page->lru, &h->hugepage_activelist);
+ hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, page);
spin_unlock(&hugetlb_lock);
}
set_page_private(page, (unsigned long)spool);
vma_commit_reservation(h, vma, addr);
- /* update page cgroup details */
- hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, page);
return page;
}
diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c
index 8e7ca0a..d4f3f7b 100644
--- a/mm/hugetlb_cgroup.c
+++ b/mm/hugetlb_cgroup.c
@@ -218,6 +218,7 @@ done:
return ret;
}
+/* Should be called with hugetlb_lock held */
void hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages,
struct hugetlb_cgroup *h_cg,
struct page *page)
@@ -225,9 +226,7 @@ void hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages,
if (hugetlb_cgroup_disabled() || !h_cg)
return;
- spin_lock(&hugetlb_lock);
set_hugetlb_cgroup(page, h_cg);
- spin_unlock(&hugetlb_lock);
return;
}
--
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