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authorHaicheng Li <haicheng.li@linux.intel.com>2010-05-24 14:32:52 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-05-25 08:07:02 -0700
commit4eaf3f64397c3db3c5785eee508270d62a9fabd9 (patch)
treebfd986a7e974876755ea6fe0de394199c68e2e36 /include/linux/mmzone.h
parent1f522509c77a5dea8dc384b735314f03908a6415 (diff)
mem-hotplug: fix potential race while building zonelist for new populated zone
Add global mutex zonelists_mutex to fix the possible race: CPU0 CPU1 CPU2 (1) zone->present_pages += online_pages; (2) build_all_zonelists(); (3) alloc_page(); (4) free_page(); (5) build_all_zonelists(); (6) __build_all_zonelists(); (7) zone->pageset = alloc_percpu(); In step (3,4), zone->pageset still points to boot_pageset, so bad things may happen if 2+ nodes are in this state. Even if only 1 node is accessing the boot_pageset, (3) may still consume too much memory to fail the memory allocations in step (7). Besides, atomic operation ensures alloc_percpu() in step (7) will never fail since there is a new fresh memory block added in step(6). [haicheng.li@linux.intel.com: hold zonelists_mutex when build_all_zonelists] Signed-off-by: Haicheng Li <haicheng.li@linux.intel.com> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Reviewed-by: Andi Kleen <andi.kleen@intel.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/mmzone.h')
-rw-r--r--include/linux/mmzone.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index a367ed5bb3fe..0fa491326c4a 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -650,6 +650,7 @@ typedef struct pglist_data {
#include <linux/memory_hotplug.h>
+extern struct mutex zonelists_mutex;
void get_zone_counts(unsigned long *active, unsigned long *inactive,
unsigned long *free);
void build_all_zonelists(void *data);