Re: [PATCH] memcg: fix memcg_cache_name() to use cgroup_name()

Michal Hocko
2013-03-22T09:48:32Z

On Fri 22-03-13 13:41:40, Glauber Costa wrote:
> On 03/22/2013 01:31 PM, Michal Hocko wrote:
> > On Fri 22-03-13 12:22:23, Glauber Costa wrote:
> >> On 03/22/2013 12:17 PM, Li Zefan wrote:
> >>>> GFP_TEMPORARY groups short lived allocations but the mem cache is not
> >>>>> an ideal candidate of this type of allocations..
> >>>>>
> >>> I'm not sure I'm following you...
> >>>
> >>> char *memcg_cache_name()
> >>> {
> >>> char *name = alloc();
> >>> return name;
> >>> }
> >>>
> >>> kmem_cache_dup()
> >>> {
> >>> name = memcg_cache_name();
> >>> kmem_cache_create_memcg(name);
> >>> free(name);
> >>> }
> >>>
> >>> Isn't this a short lived allocation?
> >>>
> >>
> >> Hi,
> >>
> >> Thanks for identifying and fixing this.
> >>
> >> Li is right. The cache name will live long, but this is because the
> >> slab/slub caches will strdup it internally. So the actual memcg
> >> allocation is short lived.
> >
> > OK, I have totally missed that. Sorry about the confusion. Then all the
> > churn around the allocation is pointless, no?
> > What about:
>
> If we're really not concerned about stack, then yes. Even if always
> running from workqueues, a PAGE_SIZEd stack variable seems risky to me.

This is not on stack. It is static

--
Michal Hocko
SUSE Labs