Messages in this thread Patch in this message | | | Date | Tue, 25 May 2010 13:05:50 +0800 | From | Haicheng Li <> | Subject | Re: [PATCH] cpu_up: hold zonelists_mutex when build_all_zonelists |
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Andrew Morton wrote: > On Thu, 20 May 2010 11:23:16 +0800 > Haicheng Li <haicheng.li@linux.intel.com> 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
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