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Subject[PATCH] [9/11] SYSCTL: Add a mutex to the page_alloc zone order sysctl
Date

The zone list code clearly cannot tolerate concurrent writers (I couldn't find
any locks for that), so simply add a global mutex. No need for RCU in this case.

Signed-off-by: Andi Kleen <ak@linux.intel.com>

---
mm/page_alloc.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

Index: linux-2.6.33-rc1-ak/mm/page_alloc.c
===================================================================
--- linux-2.6.33-rc1-ak.orig/mm/page_alloc.c
+++ linux-2.6.33-rc1-ak/mm/page_alloc.c
@@ -2401,13 +2401,14 @@ int numa_zonelist_order_handler(ctl_tabl
{
char saved_string[NUMA_ZONELIST_ORDER_LEN];
int ret;
+ static DEFINE_MUTEX(zl_order_mutex);

+ mutex_lock(&zl_order_mutex);
if (write)
- strncpy(saved_string, (char*)table->data,
- NUMA_ZONELIST_ORDER_LEN);
+ strcpy(saved_string, (char*)table->data);
ret = proc_dostring(table, write, buffer, length, ppos);
if (ret)
- return ret;
+ goto out;
if (write) {
int oldval = user_zonelist_order;
if (__parse_numa_zonelist_order((char*)table->data)) {
@@ -2420,7 +2421,9 @@ int numa_zonelist_order_handler(ctl_tabl
} else if (oldval != user_zonelist_order)
build_all_zonelists();
}
- return 0;
+out:
+ mutex_unlock(&zl_order_mutex);
+ return ret;
}



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