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| author | Cody P Schafer <cody@linux.vnet.ibm.com> | 2013-07-03 22:01:29 (GMT) |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-07-03 23:07:26 (GMT) |
| commit | c8e251fadc6220261f6e0c6b8a4f1cdf27626165 (patch) | |
| tree | 434ddbf9a6fd9e9f62e8d04e8d7be8a2a0e19a59 /mm/page_alloc.c | |
| parent | 4008bab7b3969ad9f9dd1d02096a3f0aa5610bd2 (diff) | |
| download | linux-c8e251fadc6220261f6e0c6b8a4f1cdf27626165.tar.xz | |
mm/page_alloc: prevent concurrent updaters of pcp ->batch and ->high
Because we are going to rely upon a careful transision between old and new
->high and ->batch values using memory barriers and will remove
stop_machine(), we need to prevent multiple updaters from interweaving
their memory writes.
Add a simple mutex to protect both update loops.
Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com>
Cc: Gilad Ben-Yossef <gilad@benyossef.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Pekka Enberg <penberg@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 | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index d4bcc20..8d43357 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -65,6 +65,9 @@ #include <asm/div64.h> #include "internal.h" +/* prevent >1 _updater_ of zone percpu pageset ->high and ->batch fields */ +static DEFINE_MUTEX(pcp_batch_high_lock); + #ifdef CONFIG_USE_PERCPU_NUMA_NODE_ID DEFINE_PER_CPU(int, numa_node); EXPORT_PER_CPU_SYMBOL(numa_node); @@ -5557,6 +5560,8 @@ int percpu_pagelist_fraction_sysctl_handler(ctl_table *table, int write, ret = proc_dointvec_minmax(table, write, buffer, length, ppos); if (!write || (ret < 0)) return ret; + + mutex_lock(&pcp_batch_high_lock); for_each_populated_zone(zone) { for_each_possible_cpu(cpu) { unsigned long high; @@ -5565,6 +5570,7 @@ int percpu_pagelist_fraction_sysctl_handler(ctl_table *table, int write, per_cpu_ptr(zone->pageset, cpu), high); } } + mutex_unlock(&pcp_batch_high_lock); return 0; } @@ -6078,7 +6084,9 @@ static int __meminit __zone_pcp_update(void *data) void __meminit zone_pcp_update(struct zone *zone) { + mutex_lock(&pcp_batch_high_lock); stop_machine(__zone_pcp_update, zone, NULL); + mutex_unlock(&pcp_batch_high_lock); } #endif |