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SubjectRe: [PATCH] cpu_up: hold zonelists_mutex when build_all_zonelists
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)?

> --- 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.




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