From 9adb62a5df9c0fbef7b4665919329f73a34651ed Mon Sep 17 00:00:00 2001 From: Jiang Liu Date: Tue, 31 Jul 2012 16:43:28 -0700 Subject: mm/hotplug: correctly setup fallback zonelists when creating new pgdat When hotadd_new_pgdat() is called to create new pgdat for a new node, a fallback zonelist should be created for the new node. There's code to try to achieve that in hotadd_new_pgdat() as below: /* * The node we allocated has no zone fallback lists. For avoiding * to access not-initialized zonelist, build here. */ mutex_lock(&zonelists_mutex); build_all_zonelists(pgdat, NULL); mutex_unlock(&zonelists_mutex); But it doesn't work as expected. When hotadd_new_pgdat() is called, the new node is still in offline state because node_set_online(nid) hasn't been called yet. And build_all_zonelists() only builds zonelists for online nodes as: for_each_online_node(nid) { pg_data_t *pgdat = NODE_DATA(nid); build_zonelists(pgdat); build_zonelist_cache(pgdat); } Though we hope to create zonelist for the new pgdat, but it doesn't. So add a new parameter "pgdat" the build_all_zonelists() to build pgdat for the new pgdat too. Signed-off-by: Jiang Liu Signed-off-by: Xishi Qiu Cc: Mel Gorman Cc: Michal Hocko Cc: Minchan Kim Cc: Rusty Russell Cc: Yinghai Lu Cc: Tony Luck Cc: KAMEZAWA Hiroyuki Cc: KOSAKI Motohiro Cc: David Rientjes Cc: Keping Chen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memory_hotplug.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'mm/memory_hotplug.c') diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 427bb291dd0f..b8731040b9f9 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -513,7 +513,7 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages) zone->present_pages += onlined_pages; zone->zone_pgdat->node_present_pages += onlined_pages; if (need_zonelists_rebuild) - build_all_zonelists(zone); + build_all_zonelists(NULL, zone); else zone_pcp_update(zone); @@ -562,7 +562,7 @@ static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start) * to access not-initialized zonelist, build here. */ mutex_lock(&zonelists_mutex); - build_all_zonelists(NULL); + build_all_zonelists(pgdat, NULL); mutex_unlock(&zonelists_mutex); return pgdat; -- cgit v1.3-14-g43fede From 08dff7b7d629807dbb1f398c68dd9cd58dd657a1 Mon Sep 17 00:00:00 2001 From: Jiang Liu Date: Tue, 31 Jul 2012 16:43:30 -0700 Subject: mm/hotplug: correctly add new zone to all other nodes' zone lists When online_pages() is called to add new memory to an empty zone, it rebuilds all zone lists by calling build_all_zonelists(). But there's a bug which prevents the new zone to be added to other nodes' zone lists. online_pages() { build_all_zonelists() ..... node_set_state(zone_to_nid(zone), N_HIGH_MEMORY) } Here the node of the zone is put into N_HIGH_MEMORY state after calling build_all_zonelists(), but build_all_zonelists() only adds zones from nodes in N_HIGH_MEMORY state to the fallback zone lists. build_all_zonelists() ->__build_all_zonelists() ->build_zonelists() ->find_next_best_node() ->for_each_node_state(n, N_HIGH_MEMORY) So memory in the new zone will never be used by other nodes, and it may cause strange behavor when system is under memory pressure. So put node into N_HIGH_MEMORY state before calling build_all_zonelists(). Signed-off-by: Jianguo Wu Signed-off-by: Jiang Liu Cc: Mel Gorman Cc: Michal Hocko Cc: Minchan Kim Cc: Rusty Russell Cc: Yinghai Lu Cc: Tony Luck Cc: KAMEZAWA Hiroyuki Cc: KOSAKI Motohiro Cc: David Rientjes Cc: Keping Chen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memory_hotplug.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) (limited to 'mm/memory_hotplug.c') diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index b8731040b9f9..597d371329d3 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -512,19 +512,20 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages) zone->present_pages += onlined_pages; zone->zone_pgdat->node_present_pages += onlined_pages; - if (need_zonelists_rebuild) - build_all_zonelists(NULL, zone); - else - zone_pcp_update(zone); + if (onlined_pages) { + node_set_state(zone_to_nid(zone), N_HIGH_MEMORY); + if (need_zonelists_rebuild) + build_all_zonelists(NULL, zone); + else + zone_pcp_update(zone); + } mutex_unlock(&zonelists_mutex); init_per_zone_wmark_min(); - if (onlined_pages) { + if (onlined_pages) kswapd_run(zone_to_nid(zone)); - node_set_state(zone_to_nid(zone), N_HIGH_MEMORY); - } vm_total_pages = nr_free_pagecache_pages(); -- cgit v1.3-14-g43fede From 340175b7d14d5617559d0c1a54fa0ea204d9edcd Mon Sep 17 00:00:00 2001 From: Jiang Liu Date: Tue, 31 Jul 2012 16:43:32 -0700 Subject: mm/hotplug: free zone->pageset when a zone becomes empty When a zone becomes empty after memory offlining, free zone->pageset. Otherwise it will cause memory leak when adding memory to the empty zone again because build_all_zonelists() will allocate zone->pageset for an empty zone. Signed-off-by: Jiang Liu Signed-off-by: Wei Wang Cc: Mel Gorman Cc: Michal Hocko Cc: Minchan Kim Cc: Rusty Russell Cc: Yinghai Lu Cc: Tony Luck Cc: KAMEZAWA Hiroyuki Cc: KOSAKI Motohiro Cc: David Rientjes Cc: Keping Chen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mm.h | 1 + mm/memory_hotplug.c | 3 +++ mm/page_alloc.c | 13 +++++++++++++ 3 files changed, 17 insertions(+) (limited to 'mm/memory_hotplug.c') diff --git a/include/linux/mm.h b/include/linux/mm.h index 3955bedeeed1..7c6dfd2faa69 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1331,6 +1331,7 @@ void warn_alloc_failed(gfp_t gfp_mask, int order, const char *fmt, ...); extern void setup_per_cpu_pageset(void); extern void zone_pcp_update(struct zone *zone); +extern void zone_pcp_reset(struct zone *zone); /* nommu.c */ extern atomic_long_t mmap_pages_allocated; diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 597d371329d3..3ad25f9d1fc1 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -966,6 +966,9 @@ repeat: init_per_zone_wmark_min(); + if (!populated_zone(zone)) + zone_pcp_reset(zone); + if (!node_present_pages(node)) { node_clear_state(node, N_HIGH_MEMORY); kswapd_stop(node); diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 9ad6866ac49c..9c9a31665a78 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -5894,6 +5894,19 @@ void free_contig_range(unsigned long pfn, unsigned nr_pages) #endif #ifdef CONFIG_MEMORY_HOTREMOVE +void zone_pcp_reset(struct zone *zone) +{ + unsigned long flags; + + /* avoid races with drain_pages() */ + local_irq_save(flags); + if (zone->pageset != &boot_pageset) { + free_percpu(zone->pageset); + zone->pageset = &boot_pageset; + } + local_irq_restore(flags); +} + /* * All pages in the range must be isolated before calling this. */ -- cgit v1.3-14-g43fede