On Thu 05-07-12 02:44:56, Johannes Weiner wrote:
> Not all uncharge paths need to check if the page is swapcache, some of
> them can know for sure.
>
> Push down the check into all callsites of uncharge_common() so that
> the patch that removes some of them is more obvious.
>
> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
with the fix later in the thread
Acked-by: Michal Hocko <mhocko@xxxxxxx>
> ---
> mm/memcontrol.c | 18 ++++++++++++------
> 1 files changed, 12 insertions(+), 6 deletions(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 4ea19c6..a3bf414 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -2920,8 +2920,7 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype,
> if (mem_cgroup_disabled())
> return NULL;
>
> - if (PageSwapCache(page))
> - return NULL;
> + VM_BUG_ON(PageSwapCache(page));
>
> if (PageTransHuge(page)) {
> nr_pages <<= compound_order(page);
> @@ -3018,6 +3017,8 @@ void mem_cgroup_uncharge_page(struct page *page)
> if (page_mapped(page))
> return;
> VM_BUG_ON(page->mapping && !PageAnon(page));
> + if (PageSwapCache(page))
> + return;
> __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_ANON, false);
> }
>
> @@ -3025,6 +3026,8 @@ void mem_cgroup_uncharge_cache_page(struct page *page)
> {
> VM_BUG_ON(page_mapped(page));
> VM_BUG_ON(page->mapping);
> + if (PageSwapCache(page))
> + return;
> __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_CACHE, false);
> }
>
> @@ -3089,6 +3092,8 @@ mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
> if (!swapout) /* this was a swap cache but the swap is unused ! */
> ctype = MEM_CGROUP_CHARGE_TYPE_DROP;
>
> + if (PageSwapCache(page))
> + return;
> memcg = __mem_cgroup_uncharge_common(page, ctype, false);
>
> /*
> @@ -3278,10 +3283,11 @@ void mem_cgroup_end_migration(struct mem_cgroup *memcg,
> unused = oldpage;
> }
> anon = PageAnon(used);
> - __mem_cgroup_uncharge_common(unused,
> - anon ? MEM_CGROUP_CHARGE_TYPE_ANON
> - : MEM_CGROUP_CHARGE_TYPE_CACHE,
> - true);
> + if (!PageSwapCache(page))
> + __mem_cgroup_uncharge_common(unused,
> + anon ? MEM_CGROUP_CHARGE_TYPE_ANON
> + : MEM_CGROUP_CHARGE_TYPE_CACHE,
> + true);
> css_put(&memcg->css);
> /*
> * We disallowed uncharge of pages under migration because mapcount
> --
> 1.7.7.6
>
--
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9
Czech Republic
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