Andrew Morton wrote:
On Thu, 20 May 2010 11:23:16 +0800
Haicheng Li <haicheng.li@xxxxxxxxxxxxxxx> wrote:
Here is another issue, we should always hold zonelists_mutex when calling build_all_zonelists
unless system_state == SYSTEM_BOOTING.
Taking a global mutex in the cpu-hotplug code is worrisome. Perhaps
because of the two years spent weeding out strange deadlocks between
cpu-hotplug and cpufreq.
Has this change been carefully and fully tested with lockdep enabled
(please)?
Yes, Andrew. I've tested it with lockdep enabled, and there was *no*
issue found for this change in my testing.
My test box: CPUs on node 1~3 are all offlined (16 cpus per node).
Here are my test steps:
on tty0:
# cd /sys/devices/system/node/node1
# for i in cpu*; do echo 1 > $i/online; done
on tty1:
# cd /sys/devices/system/node/node2
# for i in cpu*; do echo 1 > $i/online; done
on tty2:
# cd /sys/devices/system/node/node3
# for i in cpu*; do echo 1 > $i/online; done
on tty3:
# cat zonelist
#! /bin/bash
set -x
while ((1)); do
echo n > /proc/sys/vm/numa_zonelist_order
sleep 10
echo z > /proc/sys/vm/numa_zonelist_order
sleep 10
done
# ./zonelist
Besides, I also ran some cpu online/offline tests from LTP/cpu_hotplug test suites.
They worked fine too.
--- 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);
+ }
Your email client is performing space-stuffing and it replaces tabs
with spaces. This requires me to edit the patches rather a lot,
which is dull.
Really sorry for the inconvenience to you. I'll pay more attention
next time. thank you!
-haicheng
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxxx For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>