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SYSCTL: Add a mutex to the page_alloc zone order sysctl

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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>
This commit is contained in:
Andi Kleen 2009-12-23 21:00:47 +01:00
parent 4440095c82
commit 443c6f145d
1 changed files with 7 additions and 4 deletions
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11
mm/page_alloc.c
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@ -2402,13 +2402,14 @@ int numa_zonelist_order_handler(ctl_table *table, int write,
{
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)) {
@ -2421,7 +2422,9 @@ int numa_zonelist_order_handler(ctl_table *table, int write,
} else if (oldval != user_zonelist_order)
build_all_zonelists();
}
return 0;
out:
mutex_unlock(&zl_order_mutex);
return ret;
}