On Wed, 22 Feb 2012, Konstantin Khlebnikov wrote: > Hugh Dickins wrote: > > > > I'll have to come back to think about your locking later too; > > or maybe that's exactly where I need to look, when investigating > > the mm_inline.h:41 BUG. > > pages_count[] updates looks correct. > This really may be bug in locking, and this VM_BUG_ON catch it before > list-debug. I've still not got into looking at it yet. You're right to mention DEBUG_LIST: I have that on some of the machines, and I would expect that to be the first to catch a mislocking issue. In the past my problems with that BUG (well, the spur to introduce it) came from hugepages. > > > > But at first sight, I have to say I'm very suspicious: I've never found > > PageLRU a good enough test for whether we need such a lock, because of > > races with those pages on percpu lruvec about to be put on the lru. > > > > But maybe once I look closer, I'll find that's handled by your changes > > away from lruvec; though I'd have thought the same issue exists, > > independent of whether the pending pages are in vector or list. > > Are you talking about my per-cpu page-lists for lru-adding? Yes. > This is just an unnecessary patch, I don't know why I include it into v2 set. > It does not protect anything. Okay. Hugh -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>