On Tue, 7 Feb 2012, Anton Vorontsov wrote:

> Checking for task->mm is dangerous as ->mm might disappear (exit_mm()
> assigns NULL under task_lock(), so tasklist lock is not enough).
> 
> We can't use get_task_mm()/mmput() pair as mmput() might sleep,
> so let's take the task lock while we care about its mm.
> 
> Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>

Acked-by: David Rientjes <rientjes@google.com>