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| author | Haicheng Li <haicheng.li@linux.intel.com> | 2010-05-25 01:32:52 +0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-05-25 19:07:02 +0400 |
| commit | 4eaf3f64397c3db3c5785eee508270d62a9fabd9 (patch) | |
| tree | bfd986a7e974876755ea6fe0de394199c68e2e36 /kernel/cpu.c | |
| parent | 1f522509c77a5dea8dc384b735314f03908a6415 (diff) | |
| download | linux-4eaf3f64397c3db3c5785eee508270d62a9fabd9.tar.xz | |
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/cpu.c')
| -rw-r--r-- | kernel/cpu.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c index 3e8b3ba27175..124ad9d6be16 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(); |