Wanpeng Li <liwp.linux@xxxxxxxxx> writes: > On Wed, Jul 11, 2012 at 02:02:23PM +0530, Aneesh Kumar K.V wrote: >>Wanpeng Li <liwp.linux@xxxxxxxxx> writes: >> >>> From: Wanpeng Li <liwp@xxxxxxxxxxxxxxxxxx> >>> >>> hugepage_activelist is used to track currently used HugeTLB pages. >>> We can find the in-use HugeTLB pages to support HugeTLB cgroup >>> removal. Don't keep unused page in hugetlb_activelist too long. >>> Otherwise, on cgroup removal we should update the unused page's >>> charge to parent count. To reduce this overhead, remove unused page >>> from hugepage_activelist immediately. >>> >>> Signed-off-by: Wanpeng Li <liwp.linux@xxxxxxxxx> >>> --- >>> mm/hugetlb_cgroup.c | 1 + >>> 1 files changed, 1 insertions(+), 0 deletions(-) >>> >>> diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c >>> index b834e8d..d819d66 100644 >>> --- a/mm/hugetlb_cgroup.c >>> +++ b/mm/hugetlb_cgroup.c >>> @@ -398,6 +398,7 @@ void hugetlb_cgroup_migrate(struct page *oldhpage, struct page *newhpage) >>> spin_lock(&hugetlb_lock); >>> h_cg = hugetlb_cgroup_from_page(oldhpage); >>> set_hugetlb_cgroup(oldhpage, NULL); >>> + list_del(&oldhpage->lru); >>> >>> /* move the h_cg details to new cgroup */ >>> set_hugetlb_cgroup(newhpage, h_cg); >> >>put_page on the oldhpage will do that. If we do list_del here >>free_huge_page() will have error list_move(). > > I don't know if move the page to other lists when migration in order > to reduce overhead I mentioned make sense. :-) > Even if we are in the active_list, we don't get anything wrong because hugetlb cgroup is set to NULL for the old hugetlb page. The above patch is wrong and will result in crash when we try to put_page the oldhpage. -aneesh -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
