On Mon 20-10-14 19:55:54, Vladimir Davydov wrote:
> If we fail to reclaim anything from a cgroup during a soft reclaim pass
> we want to get the next largest cgroup exceeding its soft limit. To
> achieve this, we should obviously remove the current group from the tree
> and then pick the largest group. Currently we have a weird loop instead.
> Let's simplify it.
>
> Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxx>
> ---
> mm/memcontrol.c | 26 ++++----------------------
> 1 file changed, 4 insertions(+), 22 deletions(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index e957f0c80c6e..53393e27ff03 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -3507,34 +3507,16 @@ unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
> nr_reclaimed += reclaimed;
> *total_scanned += nr_scanned;
> spin_lock_irq(&mctz->lock);
> + __mem_cgroup_remove_exceeded(mz, mctz);
>
> /*
> * If we failed to reclaim anything from this memory cgroup
> * it is time to move on to the next cgroup
> */
> next_mz = NULL;
> - if (!reclaimed) {
> - do {
> - /*
> - * Loop until we find yet another one.
> - *
> - * By the time we get the soft_limit lock
> - * again, someone might have aded the
> - * group back on the RB tree. Iterate to
> - * make sure we get a different mem.
> - * mem_cgroup_largest_soft_limit_node returns
> - * NULL if no other cgroup is present on
> - * the tree
> - */
> - next_mz =
> - __mem_cgroup_largest_soft_limit_node(mctz);
> - if (next_mz == mz)
> - css_put(&next_mz->memcg->css);
> - else /* next_mz == NULL or other memcg */
> - break;
> - } while (1);
> - }
> - __mem_cgroup_remove_exceeded(mz, mctz);
> + if (!reclaimed)
> + next_mz = __mem_cgroup_largest_soft_limit_node(mctz);
> +
> excess = soft_limit_excess(mz->memcg);
> /*
> * One school of thought says that we should not add
> --
> 1.7.10.4
>
--
Michal Hocko
SUSE Labs
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