Messages in this thread Patch in this message | | | From | "Huang, Ying" <> | Subject | [PATCH -mm -v3 09/12] memcg, THP, swap: Avoid to duplicated charge THP in swap cache | Date | Mon, 24 Jul 2017 13:18:37 +0800 |
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From: Huang Ying <ying.huang@intel.com>
For a THP (Transparent Huge Page), tail_page->mem_cgroup is NULL. So to check whether the page is charged already, we need to check the head page. This is not an issue before because it is impossible for a THP to be in the swap cache before. But after we add delaying splitting THP after swapped out support, it is possible now.
Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> --- mm/memcontrol.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index c2618bd8ebdd..a627b0fd67ea 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5407,7 +5407,7 @@ int mem_cgroup_try_charge(struct page *page, struct mm_struct *mm, * in turn serializes uncharging. */ VM_BUG_ON_PAGE(!PageLocked(page), page); - if (page->mem_cgroup) + if (compound_head(page)->mem_cgroup) goto out; if (do_swap_account) { -- 2.13.2
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