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author | 2010-05-24 14:32:52 -0700 | |
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committer | 2010-05-25 08:07:02 -0700 | |
commit | 4eaf3f64397c3db3c5785eee508270d62a9fabd9 (patch) | |
tree | bfd986a7e974876755ea6fe0de394199c68e2e36 /mm/page_alloc.c | |
parent | mem-hotplug: avoid multiple zones sharing same boot strapping boot_pageset (diff) | |
download | linux-4eaf3f64397c3db3c5785eee508270d62a9fabd9.tar.gz linux-4eaf3f64397c3db3c5785eee508270d62a9fabd9.tar.bz2 linux-4eaf3f64397c3db3c5785eee508270d62a9fabd9.zip |
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 'mm/page_alloc.c')
-rw-r--r-- | mm/page_alloc.c | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 21c52d2d8624..08b349931ebc 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2571,8 +2571,11 @@ int numa_zonelist_order_handler(ctl_table *table, int write, strncpy((char*)table->data, saved_string, NUMA_ZONELIST_ORDER_LEN); user_zonelist_order = oldval; - } else if (oldval != user_zonelist_order) + } else if (oldval != user_zonelist_order) { + mutex_lock(&zonelists_mutex); build_all_zonelists(NULL); + mutex_unlock(&zonelists_mutex); + } } out: mutex_unlock(&zl_order_mutex); @@ -2924,6 +2927,12 @@ static void setup_pageset(struct per_cpu_pageset *p, unsigned long batch); static DEFINE_PER_CPU(struct per_cpu_pageset, boot_pageset); static void setup_zone_pageset(struct zone *zone); +/* + * Global mutex to protect against size modification of zonelists + * as well as to serialize pageset setup for the new populated zone. + */ +DEFINE_MUTEX(zonelists_mutex); + /* return values int ....just for stop_machine() */ static __init_refok int __build_all_zonelists(void *data) { @@ -2967,6 +2976,10 @@ static __init_refok int __build_all_zonelists(void *data) return 0; } +/* + * Called with zonelists_mutex held always + * unless system_state == SYSTEM_BOOTING. + */ void build_all_zonelists(void *data) { set_zonelist_order(); |