On Thu, 22 May 2008 17:46:54 +0900
Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx> wrote:
> > ==
> > #ifdef CONFIG_CGROUP_SWAP_RES_CTR
> > void swap_cgroup_init_memcg(p, memcg)
> > {
> > do something.
> > }
> > #else
> > void swap_cgroup_init_memcg(p, memcg)
> > {
> > }
> > #endif
> > ==
> >
> I think swap_cgroup_init_memcg should return old value
> of p->memcg, and I would like to name it swap_cgroup_clear_memcg,
> because it is called by sys_swapoff, so "clear" rather than "init"
> would be better.
>
> How about something like this?
>
> struct mem_cgroup **swap_cgroup_clear_memcg(p, memcg)
> {
> struct mem_cgroup **mem;
>
> mem = p->memcg;
> p->memcg = NULL;
>
> return mem;
> }
>
> and at sys_swapoff():
>
> struct mem_cgroup **memcg;
> :
> memcg = swap_cgroup_clear_memcg(p, memcg);
> :
> if (memcg)
> vfree(memcg);
>
seems good.
> >> +#ifdef CONFIG_CGROUP_SWAP_RES_CTLR
> >> + p->memcg = vmalloc(maxpages * sizeof(struct mem_cgroup *));
> >> + if (!p->memcg) {
> >> + error = -ENOMEM;
> >> + goto bad_swap;
> >> + }
> >> + memset(p->memcg, 0, maxpages * sizeof(struct mem_cgroup *));
> >> +#endif
> > void alloc_swap_ctlr_memcg(p)
> >
> OK.
> I'll implement swap_cgroup_alloc_memcg.
>
> > But this implies swapon will fail at memory shortage. Is it good ?
> >
> Hum.
> Would it be better to just disabling this feature?
>
I have no good idea. IMHO, adding printk() to show 'fatal status of
not-enough-memory-for-vmalloc' will be first step.
I believe vmalloc() tend not to fail on 64bit machine, but on i386,
vmalloc area is not enough.
Thanks,
-Kame
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