Messages in this thread | | | Date | Mon, 09 Jul 2012 11:42:12 +0900 | From | Kamezawa Hiroyuki <> | Subject | Re: [patch 04/11] mm: memcg: push down PageSwapCache check into uncharge entry functions |
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(2012/07/05 9:44), 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@cmpxchg.org> > ---
some nitpick.
> 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);
!PageSwapCache(unused) ?
But I think unused page's PG_swapcache is always dropped. So, the check is not necessary.
Thanks, -Kame
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