On Thu 29-05-14 12:15:57, Johannes Weiner wrote: > When mem_cgroup_try_charge() returns -EINTR, it bypassed the charge to > the root memcg. But move precharging does not catch this and treats > this case as if no charge had happened, thus leaking a charge against > root. Because of an old optimization, the root memcg's res_counter is > not actually charged right now, but it's still an imbalance and > subsequent patches will charge the root memcg again. > > Catch those bypasses to the root memcg and properly cancel them before > giving up the move. > > Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxx> > --- > mm/memcontrol.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 8957d6c945b8..184e67cce4e4 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -6485,8 +6485,15 @@ one_by_one: > cond_resched(); > } > ret = mem_cgroup_try_charge(memcg, GFP_KERNEL, 1, false); > + /* > + * In case of failure, any residual charges against > + * mc.to will be dropped by mem_cgroup_clear_mc() > + * later on. However, cancel any charges that are > + * bypassed to root right away or they'll be lost. > + */ > + if (ret == -EINTR) > + __mem_cgroup_cancel_charge(root_mem_cgroup, 1); > if (ret) > - /* mem_cgroup_clear_mc() will do uncharge later */ > return ret; > mc.precharge++; > } > -- > 1.9.3 > -- Michal Hocko SUSE Labs -- 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>