On Thu, Sep 20, 2012 at 09:17:43AM +0800, Wen Congyang wrote: > At 09/20/2012 04:17 AM, Minchan Kim Wrote: > > Hi KOSAKI, > > > > On Wed, Sep 19, 2012 at 02:05:20PM -0400, KOSAKI Motohiro wrote: > >> On Wed, Sep 19, 2012 at 3:29 AM, Minchan Kim <minchan@xxxxxxxxxx> wrote: > >>> During memory-hotplug stress test, 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 > >>> without draining vm_stat_diff of all CPU. > >>> > >>> This patch fixes it. > >> > >> zone_pcp_update() is called from online pages path. but IMHO, > >> the statistics should be drained offline path. isn't it? > > > > It isn't necessary because statistics is right until we reset it to zero > > in online path. > > Do you have something on your mind that we have to drain it in offline path? > > When a node is offlined and onlined again. We create node_data[i] in the I would like to clarify your word. Create or recreate? Why I have a question is as I look over the source code, hotadd_new_pgdat seem to be called if we do hotadd *new* memory. It's not the case for offline and online again you mentioned. If you're right, I should find arch_free_nodedata to free pgdat when node is disappear but I can't find it. Do I miss something? > function hotadd_new_pgdat(), and we will lost the statistics stored in > zone->pageset. So we should drain it in offline path. Even we drain in offline patch, it still has a problem. 1. offline 2. drain -> OKAY 3. schedule 4. Process A increase zone stat 5. Process B increase zone stat 6. online 7. reset it -> we ends up lost zone stat counter which is modified between 2-6 > > Thanks > Wen Congyang > > > > >> > >> thanks. > > > > -- > 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> -- Kind regards, Minchan Kim -- 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>