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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 /kernel
parent1f522509c77a5dea8dc384b735314f03908a6415 (diff)
downloadlinux-2.6.34-ux500-4eaf3f64397c3db3c5785eee508270d62a9fabd9.tar.gz
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 'kernel')
-rw-r--r--kernel/cpu.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 3e8b3ba2717..124ad9d6be1 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -357,8 +357,11 @@ int __cpuinit cpu_up(unsigned int cpu)
return -ENOMEM;
}
- if (pgdat->node_zonelists->_zonerefs->zone == NULL)
+ if (pgdat->node_zonelists->_zonerefs->zone == NULL) {
+ mutex_lock(&zonelists_mutex);
build_all_zonelists(NULL);
+ mutex_unlock(&zonelists_mutex);
+ }
#endif
cpu_maps_update_begin();