Johannes Weiner <hannes@xxxxxxxxxxx> writes: > On Sat, Jun 09, 2012 at 02:29:59PM +0530, Aneesh Kumar K.V wrote: >> From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx> >> >> This adds necessary charge/uncharge calls in the HugeTLB code. We do >> hugetlb cgroup charge in page alloc and uncharge in compound page destructor. >> >> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx> >> --- >> mm/hugetlb.c | 16 +++++++++++++++- >> mm/hugetlb_cgroup.c | 7 +------ >> 2 files changed, 16 insertions(+), 7 deletions(-) >> >> diff --git a/mm/hugetlb.c b/mm/hugetlb.c >> index bf79131..4ca92a9 100644 >> --- a/mm/hugetlb.c >> +++ b/mm/hugetlb.c >> @@ -628,6 +628,8 @@ static void free_huge_page(struct page *page) >> BUG_ON(page_mapcount(page)); >> >> spin_lock(&hugetlb_lock); >> + hugetlb_cgroup_uncharge_page(hstate_index(h), >> + pages_per_huge_page(h), page); > > hugetlb_cgroup_uncharge_page() takes the hugetlb_lock, no? Yes, But this patch also modifies it to not take the lock, because we hold spin_lock just below in the call site. I didn't want to drop the lock and take it again. > > It's quite hard to review code that is split up like this. Please > always keep the introduction of new functions in the same patch that > adds the callsite(s). One of the reason I split the charge/uncharge routines and the callers in separate patches is to make it easier for review. Irrespective of the call site charge/uncharge routines should be correct with respect to locking and other details. What I did in this patch is a small optimization of avoiding dropping and taking the lock again. May be the right approach would have been to name it __hugetlb_cgroup_uncharge_page and make sure the hugetlb_cgroup_uncharge_page still takes spin_lock. But then we don't have any callers for that. -aneesh -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>