On 08/23/2012 06:28 PM, Minchan Kim wrote: > Okay, then, why do you think the patchsets are culprit? > I didn't look the cleanup patch series of Xiao at that time > so I can be wrong but as I just look through patch of > "zcache: optimize zcache_do_preload", I can't find any fault > because zcache_put_page checks irq_disable so we don't need > to disable preemption so it seems that patch is correct to me. > If the race happens by preemption, BUG_ON in zcache_put_page > should catch it. > > What do you mean? Do you have any clue in your mind? > > The commits undermine an assumption made by tmem_put() in > the cleancache path that preemption is disabled. I do not have an explanation right now for why these commits expose this issue. The patch looks like it should be fine to me, hence my Ack at the time. I understand and agree with you that the zcache shim functions zcache_put_page(), zcache_get_page(), zcache_flush_page(), and zcache_flush_object() all disable interrupts (or make sure that interrupts are already disabled) which implicitly disables preemption. I'm still trying to find root cause here. Seth -- 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>