Messages in this thread Patch in this message |  | | From | Johannes Weiner <> | Subject | [patch] mm: memcontrol: don't pass a NULL memcg to mem_cgroup_end_move() | Date | Thu, 23 Oct 2014 10:33:50 -0400 |
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mem_cgroup_end_move() checks if the passed memcg is NULL, along with a lengthy comment to explain why this seemingly non-sensical situation is even possible.
Check in cancel_attach() itself whether can_attach() set up the move context or not, it's a lot more obvious from there. Then remove the check and comment in mem_cgroup_end_move().
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vladimir Davydov <vdavydov@parallels.com> --- mm/memcontrol.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index a5c9aa4688e8..3cd4f1e0bfb3 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1469,12 +1469,7 @@ static void mem_cgroup_start_move(struct mem_cgroup *memcg) static void mem_cgroup_end_move(struct mem_cgroup *memcg) { - /* - * Now, mem_cgroup_clear_mc() may call this function with NULL. - * We check NULL in callee rather than caller. - */ - if (memcg) - atomic_dec(&memcg->moving_account); + atomic_dec(&memcg->moving_account); } /* @@ -5489,7 +5484,8 @@ static int mem_cgroup_can_attach(struct cgroup_subsys_state *css, static void mem_cgroup_cancel_attach(struct cgroup_subsys_state *css, struct cgroup_taskset *tset) { - mem_cgroup_clear_mc(); + if (mc.to) + mem_cgroup_clear_mc(); } static int mem_cgroup_move_charge_pte_range(pmd_t *pmd, -- 2.1.2
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