On Wed, 20 Apr 2011, Christoph Lameter wrote: > There is barely any testing going on at all of this since we have had this > issue for more than 5 years and have not noticed it. The absence of bug > reports therefore proves nothing. Code inspection of the VM shows > that this is an issue that arises in multiple subsystems and that we have > VM_BUG_ONs in the page allocator that should trigger for these situations. > > Usage of DISCONTIGMEM and !NUMA is not safe and should be flagged as such. > We don't actually have any bug reports in front of us that show anything else in the VM other than slub has issues with this configuration, so marking them as broken is probably premature. The parisc config that triggered this debugging enables CONFIG_SLAB by default, so it probably has gone unnoticed just because nobody other than James has actually tried it on hppa64. Let's see if KOSAKI-san's fixes to Kconfig (even though I'd prefer the simpler and implicit "config NUMA def_bool ARCH_DISCONTIGMEM_ENABLE" over his config NUMA) and my fix to parisc to set the bit in N_NORMAL_MEMORY so that CONFIG_SLUB initializes kmem_cache_node correctly works and then address issues in the core VM as they arise. Presumably someone has been running DISCONTIGMEM on hppa64 in the past five years without issues with defconfig, so the issue here may just be slub. -- 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 internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>