Re: [PATCH v6] fork: free vmapped stacks in cache when cpus are offline

From: Thomas Gleixner
Date: Sun Feb 12 2017 - 10:24:00 EST

On Sun, 12 Feb 2017, Hoeun Ryu wrote:

> Using virtually mapped stack, kernel stacks are allocated via vmalloc.
> In the current implementation, two stacks per cpu can be cached when
> tasks are freed and the cached stacks are used again in task duplications.
> but the cached stacks may remain unfreed even when cpu are offline.
> By adding a cpu hotplug callback to free the cached stacks when a cpu
> goes offline, the pages of the cached stacks are not wasted.
> Signed-off-by: Hoeun Ryu <hoeun.ryu@xxxxxxxxx>
> Acked-by: Michal Hocko <mhocko@xxxxxxxx>

Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>