Messages in this thread | | | Date | Tue, 24 Aug 2010 13:04:02 +0900 | From | Daisuke Nishimura <> | Subject | Re: [PATCH] memcg: use ID in page_cgroup |
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On Tue, 24 Aug 2010 10:54:05 +0900 KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> On Tue, 24 Aug 2010 10:14:25 +0900 > Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote: > > > > > > @@ -723,6 +729,11 @@ static inline bool mem_cgroup_is_root(st > > > > > return (mem == root_mem_cgroup); > > > > > } > > > > > > > > > > +static inline bool mem_cgroup_is_rootid(unsigned short id) > > > > > +{ > > > > > + return (id == 1); > > > > > +} > > > > > + > > > > It might be better to add > > > > > > > > BUG_ON(newid->id != 1) > > > > > > > > in cgroup.c::cgroup_init_idr(). > > > > > > > > > > Why ?? > > > > > Just to make sure that the root css has id==1. mem_cgroup_is_rootid() make > > use of the fact. > > I'm sorry if I miss something. > > > > Hmm. The function allocating ID does > > 4530 static struct css_id *get_new_cssid(struct cgroup_subsys *ss, int depth) > 4531 { > == > 4546 spin_lock(&ss->id_lock); > 4547 /* Don't use 0. allocates an ID of 1-65535 */ > 4548 error = idr_get_new_above(&ss->idr, newid, 1, &myid); > 4549 spin_unlock(&ss->id_lock); > == > > and allocates ID above "1", always. > > Adding BUG_ON(newid->id != 1) will mean that we doubt the bitmap function and > consider possibility that new->id == 0. > > But, we're 100% sure that it never happens. > > I don't think adding a comment is a right thing to do. > Okey, I don't have strong requirement to add BUG_ON() anyway.
These patches looks good to me except for some minor points I've commented.
Thanks, Daisuke Nishimura.
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