Re: [PATCH] use vmalloc for mem_cgroup allocation. v2

[Andrew Morton <akpm@linux-foundation.org>]

On Tue, 15 Apr 2008 10:08:25 +0800 Li Zefan <lizf@cn.fujitsu.com> wrote:

> > @@ -992,8 +993,10 @@ mem_cgroup_create(struct cgroup_subsys *
> >  	if (unlikely((cont->parent) == NULL)) {
> >  		mem = &init_mem_cgroup;
> >  		page_cgroup_cache = KMEM_CACHE(page_cgroup, SLAB_PANIC);
> > -	} else
> > -		mem = kzalloc(sizeof(struct mem_cgroup), GFP_KERNEL);
> > +	} else {
> > +		mem = vmalloc(sizeof(struct mem_cgroup));
> > +		memset(mem, 0, sizeof(*mem));
> 
> what if mem == NULL. ;)
> 
> > +	}
> >  
> >  	if (mem == NULL)
> >  		return ERR_PTR(-ENOMEM);
> 
> So we can move this NULL check to the above else branch, in the if brach,
> mem won't be NULL.

err, yes.

So I have:

	if (unlikely((cont->parent) == NULL)) {
		mem = &init_mem_cgroup;
		page_cgroup_cache = KMEM_CACHE(page_cgroup, SLAB_PANIC);
	} else {
		mem = vmalloc(sizeof(struct mem_cgroup));
		if (mem == NULL)
			return ERR_PTR(-ENOMEM);
		memset(mem, 0, sizeof(*mem));
	}