[Devel] Re: [PATCH v5 3/3] cgroups: make procs file writable

[David Rientjes]

On Thu, 30 Dec 2010, Li Zefan wrote:

> That's what we did for cpu masks :). See commit
> 2341d1b6598c7146d64a5050b53a72a5a819617f.
> 
> I made a patchset to remove on stack cpu masks.
> 
> What I meant is we don't have to allocate nodemasks in cpuset_sprintf_memlist().
> This is sufficient:
> 
> diff --git a/kernel/cpuset.c b/kernel/cpuset.c
> index 4349935..a159612 100644
> --- a/kernel/cpuset.c
> +++ b/kernel/cpuset.c
> @@ -1620,20 +1620,12 @@ static int cpuset_sprintf_cpulist(char *page, struct cpu
> 
>  static int cpuset_sprintf_memlist(char *page, struct cpuset *cs)
>  {
> -       NODEMASK_ALLOC(nodemask_t, mask, GFP_KERNEL);
>         int retval;
> 
> -       if (mask == NULL)
> -               return -ENOMEM;
> -
>         mutex_lock(&callback_mutex);
> -       *mask = cs->mems_allowed;
> +       retval = nodelist_scnprintf(page, PAGE_SIZE, cs->mems_allowed);
>         mutex_unlock(&callback_mutex);
> 
> -       retval = nodelist_scnprintf(page, PAGE_SIZE, *mask);
> -
> -       NODEMASK_FREE(mask);
> -
>         return retval;
>  }
> 

This needs to be done with cgroup_lock() instead of callback_mutex since 
the post_clone() callback will store to cs->mems_allowed on 
cgroup_clone().
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