Re: [PATCH v4 06/14] memcg: kmem controller infrastructure

Michal Hocko
2012-10-12T09:47:32Z

On Fri 12-10-12 13:13:04, Glauber Costa wrote:
[...]
> Just so we don't ping-pong in another submission:
>
> I changed memcontrol.h's memcg_kmem_newpage_charge to include:
>
> /* If the test is dying, just let it go. */
> if (unlikely(test_thread_flag(TIF_MEMDIE)
> || fatal_signal_pending(current)))
> return true;

OK

> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index c32aaaf..72cf189 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> +static int memcg_charge_kmem(struct mem_cgroup *memcg, gfp_t gfp, u64 size)
> +{
> + struct res_counter *fail_res;
> + struct mem_cgroup *_memcg;
> + int ret = 0;
> + bool may_oom;
> +
> + ret = res_counter_charge(&memcg->kmem, size, &fail_res);
> + if (ret)
> + return ret;
> +
> + /*
> + * Conditions under which we can wait for the oom_killer.
> + * We have to be able to wait, but also, if we can't retry,
> + * we obviously shouldn't go mess with oom.
> + */
> + may_oom = (gfp & __GFP_WAIT) && !(gfp & __GFP_NORETRY);
> +
> + _memcg = memcg;
> + ret = __mem_cgroup_try_charge(NULL, gfp, size >> PAGE_SHIFT,
> + &_memcg, may_oom);
> +
> + if (ret == -EINTR) {
> + /*
> + * __mem_cgroup_try_charge() chosed to bypass to root due to
> + * OOM kill or fatal signal. Since our only options are to
> + * either fail the allocation or charge it to this cgroup, do
> + * it as a temporary condition. But we can't fail. From a
> + * kmem/slab perspective, the cache has already been selected,
> + * by mem_cgroup_get_kmem_cache(), so it is too late to change
> + * our minds. This condition will only trigger if the task
> + * entered memcg_charge_kmem in a sane state, but was
> + * OOM-killed. during __mem_cgroup_try_charge. Tasks that are
> + * already dying when the allocation triggers should have been
> + * already directed to the root cgroup.
> + */
> + res_counter_charge_nofail(&memcg->res, size, &fail_res);
> + if (do_swap_account)
> + res_counter_charge_nofail(&memcg->memsw, size,
> + &fail_res);
> + ret = 0;
> + } else if (ret)
> + res_counter_uncharge(&memcg->kmem, size);
> +
> + return ret;
> +}

OK
--
Michal Hocko
SUSE Labs