On Thu, 20 Sep 2012 15:43:25 +0900 Minchan Kim <minchan@xxxxxxxxxx> wrote: > During memory-hotplug, I found NR_ISOLATED_[ANON|FILE] > are increasing so that kernel are hang out. > > The cause is that when we do memory-hotadd after memory-remove, > __zone_pcp_update clear out zone's ZONE_STAT_ITEMS in setup_pageset > although vm_stat_diff of all CPU still have value. > > In addtion, when we offline all pages of the zone, we reset them > in zone_pcp_reset without drain so that we lost zone stat item. > Here's what I ended up with for a changelog: : During memory-hotplug, I found NR_ISOLATED_[ANON|FILE] are increasing, : causing the kernel to hang. When the system doesn't have enough free : pages, it enters reclaim but never reclaim any pages due to : too_many_isolated()==true and loops forever. : : The cause is that when we do memory-hotadd after memory-remove, : __zone_pcp_update() clears a zone's ZONE_STAT_ITEMS in setup_pageset() : although the vm_stat_diff of all CPUs still have values. : : In addtion, when we offline all pages of the zone, we reset them in : zone_pcp_reset without draining so we loss some zone stat item. As memory hotplug seems fairly immature and broken, I'm thinking there's no point in backporting this into -stable. And I don't *think* we really need it in 3.6 either? (It doesn't apply cleanly to current mainline anyway - I didn't check why). -- 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>