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Date: Thu, 23 Feb 2012 19:03:52 +0100 From: Johannes Weiner <hannes@...xchg.org> To: Konstantin Khlebnikov <khlebnikov@...nvz.org> Cc: Hugh Dickins <hughd@...gle.com>, linux-kernel@...r.kernel.org, linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>, KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>, Andi Kleen <andi@...stfloor.org> Subject: Re: [PATCH v3 02/21] memcg: make mm_match_cgroup() hirarchical On Thu, Feb 23, 2012 at 05:51:46PM +0400, Konstantin Khlebnikov wrote: > Check mm-owner cgroup membership hierarchically. I think this one cat just beat up this other cat in front of my window, yelling something about money and missing product. Anyway, I already forgot why we want this patch. Could you describe that in the changelog, please? > @@ -821,6 +821,26 @@ struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p) > struct mem_cgroup, css); > } > > +/** > + * mm_match_cgroup - cgroup hierarchy mm membership test > + * @mm mm_struct to test > + * @cgroup target cgroup > + * > + * Returns true if mm belong this cgroup or any its child in hierarchy > + */ > +int mm_match_cgroup(const struct mm_struct *mm, const struct mem_cgroup *cgroup) > +{ > + struct mem_cgroup *memcg; > + > + rcu_read_lock(); > + memcg = mem_cgroup_from_task(rcu_dereference((mm)->owner)); > + while (memcg != cgroup && memcg && memcg->use_hierarchy) > + memcg = parent_mem_cgroup(memcg); > + rcu_read_unlock(); > + > + return cgroup == memcg; > +} Please don't duplicate mem_cgroup_same_or_subtree()'s functionality in a worse way. The hierarchy information is kept in a stack such that ancestry can be detected in linear time, check out css_is_ancestor(). If you don't want to nest rcu_read_lock(), you could push the rcu_read_lock() from css_is_ancestor() into its sole user and provide a __mem_cgroup_is_ancestor() that assumes rcu already read-locked. No? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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