On Thu, Nov 04, 2010 at 10:31:58AM -0700, Hugh Dickins wrote: > On Wed, 3 Nov 2010, Hiroyuki Kamezawa wrote: > > I'm sorry for attached file, I have to use unusual mailer this time. > > This is a fix for wrong VM_BUG_ON() for mm/memcontol.c > > Thanks, Kame, that's good: I've inlined it below with Balbir's Review, > my Ack, and a Cc: stable@xxxxxxxxxxx > > Hugh > > > [PATCH] memcg: fix wrong VM_BUG_ON() in try_charge()'s mm->owner check > > At __mem_cgroup_try_charge(), VM_BUG_ON(!mm->owner) is checked. > But as commented in mem_cgroup_from_task(), mm->owner can be NULL in some racy > case. This check of VM_BUG_ON() is bad. > > A possible story to hit this is at swapoff()->try_to_unuse(). It passes > mm_struct to mem_cgroup_try_charge_swapin() while mm->owner is NULL. If we > can't get proper mem_cgroup from swap_cgroup information, mm->owner is used > as charge target and we see NULL. > > Cc: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx> > Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> > Reported-by: Hugh Dickins <hughd@xxxxxxxxxx> > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> > Reviewed-by: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx> > Acked-by: Hugh Dickins <hughd@xxxxxxxxxx> > Cc: stable@xxxxxxxxxx Reviewed-by: Johannes Weiner <hannes@xxxxxxxxxxx> -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>