On Wed, 11 Jun 2014 13:34:04 +0900 Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> wrote: > > While rcu list traversal over the vmap_area_list is safe, this may > > arrive at different results than the spinlocked version. The rcu list > > traversal version will not be a 'snapshot' of a single, valid instant > > of the entire vmap_area_list, but rather a potential amalgam of > > different list states. > > Hello, > > Yes, you are right, but I don't think that we should be strict here. > Meminfo is already not a 'snapshot' at specific time. While we try to > get certain stats, the other stats can change. > And, although we may arrive at different results than the spinlocked > version, the difference would not be large and would not make serious > side-effect. mm, well... The spinlocked version will at least report a number which *used* to be true. The new improved racy version could for example see a bunch of new allocations but fail to see the bunch of frees which preceded those new allocations. Net result: it reports allocation totals which exceed anything which this kernel has ever sustained. But hey, it's only /proc/meminfo:VmallocFoo. I'll eat my hat if anyone cares about it. -- 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>