On Mon 20-10-14 11:22:09, Johannes Weiner wrote:
> mem_cgroup_swapout() is called with exclusive access to the page at
> the end of the page's lifetime. Instead of clearing the PCG_MEMSW
> flag and deferring the uncharge, just do it right away. This allows
> follow-up patches to simplify the uncharge code.
>
> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
OK, it makes sense. With the irq fixup
Acked-by: Michal Hocko <mhocko@xxxxxxx>
> ---
> mm/memcontrol.c | 17 +++++++++++++----
> 1 file changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index bea3fddb3372..7709f17347f3 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -5799,6 +5799,7 @@ static void __init enable_swap_cgroup(void)
> */
> void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
> {
> + struct mem_cgroup *memcg;
> struct page_cgroup *pc;
> unsigned short oldid;
>
> @@ -5815,13 +5816,21 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
> return;
>
> VM_BUG_ON_PAGE(!(pc->flags & PCG_MEMSW), page);
> + memcg = pc->mem_cgroup;
>
> - oldid = swap_cgroup_record(entry, mem_cgroup_id(pc->mem_cgroup));
> + oldid = swap_cgroup_record(entry, mem_cgroup_id(memcg));
> VM_BUG_ON_PAGE(oldid, page);
> + mem_cgroup_swap_statistics(memcg, true);
>
> - pc->flags &= ~PCG_MEMSW;
> - css_get(&pc->mem_cgroup->css);
> - mem_cgroup_swap_statistics(pc->mem_cgroup, true);
> + pc->flags = 0;
> +
> + if (!mem_cgroup_is_root(memcg))
> + page_counter_uncharge(&memcg->memory, 1);
> +
> + local_irq_disable();
> + mem_cgroup_charge_statistics(memcg, page, -1);
> + memcg_check_events(memcg, page);
> + local_irq_enable();
> }
>
> /**
> --
> 2.1.2
>
--
Michal Hocko
SUSE Labs
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