From 9808895e1a4416ffb9b3a0a121d81afc5a23c18b Mon Sep 17 00:00:00 2001 From: Mina Almasry Date: Wed, 1 Apr 2020 21:11:18 -0700 Subject: [PATCH] mm/hugetlb_cgroup: fix hugetlb_cgroup migration Commit c32300516047 ("hugetlb_cgroup: add interface for charge/uncharge hugetlb reservations") mistakingly doesn't handle the migration of *both* the reservation hugetlb_cgroup and the fault hugetlb_cgroup correctly. What should happen is that both cgroups shuold be queried from the old page, then both set to NULL on the old page, then both inserted into the new page. The mistake also creates the following warning: mm/hugetlb_cgroup.c: In function 'hugetlb_cgroup_migrate': mm/hugetlb_cgroup.c:777:25: warning: variable 'h_cg' set but not used [-Wunused-but-set-variable] struct hugetlb_cgroup *h_cg; ^~~~ Solution is to add the missing steps, namly setting the reservation hugetlb_cgroup to NULL on the old page, and setting the fault hugetlb_cgroup on the new page. Fixes: c32300516047 ("hugetlb_cgroup: add interface for charge/uncharge hugetlb reservations") Reported-by: Qian Cai Signed-off-by: Mina Almasry Signed-off-by: Andrew Morton Cc: David Rientjes Cc: Greg Thelen Cc: Mike Kravetz Cc: Sandipan Das Cc: Shakeel Butt Cc: Shuah Khan Link: http://lkml.kernel.org/r/20200218194727.46995-1-almasrymina@google.com Signed-off-by: Linus Torvalds --- mm/hugetlb_cgroup.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c index 0aef0f34b80a..c5c8f8e2c2db 100644 --- a/mm/hugetlb_cgroup.c +++ b/mm/hugetlb_cgroup.c @@ -797,8 +797,10 @@ void hugetlb_cgroup_migrate(struct page *oldhpage, struct page *newhpage) h_cg = hugetlb_cgroup_from_page(oldhpage); h_cg_rsvd = hugetlb_cgroup_from_page_rsvd(oldhpage); set_hugetlb_cgroup(oldhpage, NULL); + set_hugetlb_cgroup_rsvd(oldhpage, NULL); /* move the h_cg details to new cgroup */ + set_hugetlb_cgroup(newhpage, h_cg); set_hugetlb_cgroup_rsvd(newhpage, h_cg_rsvd); list_move(&newhpage->lru, &h->hugepage_activelist); spin_unlock(&hugetlb_lock); -- 2.20.1