Re: [patch 04/12] mm: memcontrol: retry reclaim for oom-disabled and __GFP_NOFAIL charges

Michal Hocko
2014-06-17T13:53:44Z

On Mon 16-06-14 15:54:24, Johannes Weiner wrote:
> There is no reason why oom-disabled and __GFP_NOFAIL charges should
> try to reclaim only once when every other charge tries several times
> before giving up. Make them all retry the same number of times.

OK, this makes sense for oom-disabled and __GFP_NOFAIL but does it make
sense to do additional reclaim for tasks with fatal_signal_pending?

It is little bit unexpected, because we bypass if the condition happens
before the reclaim but then we ignore it.

> Signed-off-by: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
> ---
> mm/memcontrol.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index e946f7439b16..52550bbff1ef 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -2566,7 +2566,7 @@ static int mem_cgroup_try_charge(struct mem_cgroup *memcg,
> bool oom)
> {
> unsigned int batch = max(CHARGE_BATCH, nr_pages);
> - int nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES;
> + int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
> struct mem_cgroup *mem_over_limit;
> struct res_counter *fail_res;
> unsigned long nr_reclaimed;
> @@ -2638,6 +2638,9 @@ retry:
> if (mem_cgroup_wait_acct_move(mem_over_limit))
> goto retry;
>
> + if (nr_retries--)
> + goto retry;
> +
> if (gfp_mask & __GFP_NOFAIL)
> goto bypass;
>
> @@ -2647,9 +2650,6 @@ retry:
> if (!oom)
> goto nomem;
>
> - if (nr_oom_retries--)
> - goto retry;
> -
> mem_cgroup_oom(mem_over_limit, gfp_mask, get_order(batch));
> nomem:
> if (!(gfp_mask & __GFP_NOFAIL))
> --
> 2.0.0
>

--
Michal Hocko
SUSE Labs