On Tue 04-12-12 12:17:21, Michal Hocko wrote:
> On Tue 04-12-12 16:36:11, Jeff Liu wrote:
[...]
> > + * arrive here multiple times. But we only allocate pages for swap
> > + * cgroup when the first child memcg was created.
> > + */
> > +int swap_cgroup_init(void)
> > +{
> > + int type;
> > +
> > + if (!do_swap_account)
> > + return 0;
> > +
> > + if (atomic_add_return(1, &swap_cgroup_initialized) != 1)
> > + return 0;
> > +
> > + mutex_lock(&swap_cgroup_mutex);
> > + for (type = 0; type < MAX_SWAPFILES; type++) {
> > + if (swap_cgroup_alloc_pages(type) < 0) {
>
> Why do you initialize MAX_SWAPFILES rather than nr_swapfiles?
>
> Besides that swap_cgroup_alloc_pages is not sufficient because it
> doesn't allocate ctrl->map but it tries to put pages in it.
Sorry, I have missed that you have kept ctrl->map initialization in
swap_cgroup_swapon so this is not an issue.
I think you can do better if swap_cgroup_swapon only initialized
ctrl->length and deferred all the rest to swap_cgroup_alloc_pages (or
its original name as it suits better) including the map allocation which
is currently done in swap_cgroup_swapon.
--
Michal Hocko
SUSE Labs
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