Messages in this thread | | | Date | Tue, 26 May 2015 18:36:46 +0200 | From | Oleg Nesterov <> | Subject | Re: [RFC 3/3] memcg: get rid of mm_struct::owner |
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On 05/26, Michal Hocko wrote: > > @@ -426,17 +426,7 @@ struct mm_struct { > struct kioctx_table __rcu *ioctx_table; > #endif > #ifdef CONFIG_MEMCG > - /* > - * "owner" points to a task that is regarded as the canonical > - * user/owner of this mm. All of the following must be true in > - * order for it to be changed: > - * > - * current == mm->owner > - * current->mm != mm > - * new_owner->mm == mm > - * new_owner->alloc_lock is held > - */ > - struct task_struct __rcu *owner; > + struct mem_cgroup __rcu *memcg;
Yes, thanks, this is what I tried to suggest ;)
But I can't review this series. Simply because I know nothing about memcs. I don't even know how to use it.
Just one question,
> +static struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p) > +{ > + if (!p->mm) > + return NULL; > + return rcu_dereference(p->mm->memcg); > +}
Probably I missed something, but it seems that the callers do not expect it can return NULL. Perhaps sock_update_memcg() is fine, but task_in_mem_cgroup() calls it when find_lock_task_mm() fails, and in this case ->mm is NULL.
And in fact I can't understand what mem_cgroup_from_task() actually means, with or without these changes.
And another question. I can't understand what happens when a task execs... IOW, could you confirm that exec_mmap() does not need mm_set_memcg(mm, oldmm->memcg) ?
Oleg.
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