On Thu, 25 Mar 2010 18:09:34 +0900 (JST) KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> wrote: > > On Thu, 25 Mar 2010 08:32:35 +0000 > > Mel Gorman <mel@xxxxxxxxx> wrote: > > IIUC, the race in memory-hotunplug was fixed by this patch [2/11]. > > > > But, this behavior of unmap_and_move() requires access to _freed_ > > objects (spinlock). Even if it's safe because of SLAB_DESTROY_BY_RCU, > > it't not good habit in general. > > > > After direct compaction, page-migration will be one of "core" code of > > memory management. Then, I agree to patch [1/11] as our direction for > > keeping sanity and showing direction to more updates. Maybe adding > > refcnt and removing RCU in futuer is good. > > But Christoph seems oppose to remove SLAB_DESTROY_BY_RCU. then refcount > is meaningless now. I agree you if we will remove SLAB_DESTROY_BY_RCU > in the future. > removing rcu_read_lock/unlock in unmap_and_move() and removing SLAB_DESTROY_BY_RCU is different story. Thanks, -Kame -- 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/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>