Messages in this thread | | | Date | Wed, 27 Mar 2013 16:32:20 +0100 | From | Michal Hocko <> | Subject | Re: [PATCH] memcg: fix memcg_cache_name() to use cgroup_name() |
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On Wed 27-03-13 19:19:58, Glauber Costa wrote: > On 03/27/2013 07:11 PM, Michal Hocko wrote: > > On Wed 27-03-13 10:58:25, Johannes Weiner wrote: > >> On Wed, Mar 27, 2013 at 09:36:39AM +0100, Michal Hocko wrote: > > [...] > >>> + /* > >>> + * kmem_cache_create_memcg duplicates the given name and > >>> + * cgroup_name for this name requires RCU context. > >>> + * This static temporary buffer is used to prevent from > >>> + * pointless shortliving allocation. > >>> + */ > >>> + if (!tmp_name) { > >>> + tmp_name = kmalloc(PAGE_SIZE, GFP_KERNEL); > >>> + WARN_ON_ONCE(!tmp_name); > >> > >> Just use the page allocator directly and get a free allocation failure > >> warning. > > > > WARN_ON_ONCE is probably pointless. > > > >> Then again, order-0 pages are considered cheap enough that they never > >> even fail in our current implementation. > >> > >> Which brings me to my other point: why not just a simple single-page > >> allocation? > > > > No objection from me. I was previously thinking about the "proper" > > size for something that is a file name. So I originally wanted to use > > PATH_MAX instead but ended up with PAGE_SIZE for reasons I do not > > remember now. > > theoretically, this is PATH_MAX + max cache name.
So do you prefer kmalloc(PATH_MAX) or the page allocator directly as Johannes suggests? I agree tha kamlloc(PAGE_SIZE) looks weird.
-- Michal Hocko SUSE Labs
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