On Thu 23-10-14 09:57:29, Johannes Weiner wrote: [...] > From b518d88254b01be8c6c0c4a496d9f311f0c71b4a Mon Sep 17 00:00:00 2001 > From: Johannes Weiner <[email protected]> > Date: Thu, 23 Oct 2014 09:29:06 -0400 > Subject: [patch] mm: rmap: split out page_remove_file_rmap() > > page_remove_rmap() has too many branches on PageAnon() and is hard to > follow. Move the file part into a separate function. > > Signed-off-by: Johannes Weiner <[email protected]>
Reviewed-by: Michal Hocko <[email protected]> > --- > mm/rmap.c | 78 > +++++++++++++++++++++++++++++++++++++-------------------------- > 1 file changed, 46 insertions(+), 32 deletions(-) > > diff --git a/mm/rmap.c b/mm/rmap.c > index f574046f77d4..19886fb2f13a 100644 > --- a/mm/rmap.c > +++ b/mm/rmap.c > @@ -1054,6 +1054,36 @@ void page_add_file_rmap(struct page *page) > mem_cgroup_end_page_stat(memcg, locked, flags); > } > > +static void page_remove_file_rmap(struct page *page) > +{ > + struct mem_cgroup *memcg; > + unsigned long flags; > + bool locked; > + > + memcg = mem_cgroup_begin_page_stat(page, &locked, &flags); > + > + /* page still mapped by someone else? */ > + if (!atomic_add_negative(-1, &page->_mapcount)) > + goto out; > + > + /* Hugepages are not counted in NR_FILE_MAPPED for now. */ > + if (unlikely(PageHuge(page))) > + goto out; > + > + /* > + * We use the irq-unsafe __{inc|mod}_zone_page_stat because > + * these counters are not modified in interrupt context, and > + * pte lock(a spinlock) is held, which implies preemption disabled. > + */ > + __dec_zone_page_state(page, NR_FILE_MAPPED); > + mem_cgroup_dec_page_stat(memcg, MEM_CGROUP_STAT_FILE_MAPPED); > + > + if (unlikely(PageMlocked(page))) > + clear_page_mlock(page); > +out: > + mem_cgroup_end_page_stat(memcg, locked, flags); > +} > + > /** > * page_remove_rmap - take down pte mapping from a page > * @page: page to remove mapping from > @@ -1062,46 +1092,33 @@ void page_add_file_rmap(struct page *page) > */ > void page_remove_rmap(struct page *page) > { > - struct mem_cgroup *uninitialized_var(memcg); > - bool anon = PageAnon(page); > - unsigned long flags; > - bool locked; > - > - /* > - * The anon case has no mem_cgroup page_stat to update; but may > - * uncharge_page() below, where the lock ordering can deadlock if > - * we hold the lock against page_stat move: so avoid it on anon. > - */ > - if (!anon) > - memcg = mem_cgroup_begin_page_stat(page, &locked, &flags); > + if (!PageAnon(page)) { > + page_remove_file_rmap(page); > + return; > + } > > /* page still mapped by someone else? */ > if (!atomic_add_negative(-1, &page->_mapcount)) > - goto out; > + return; > + > + /* Hugepages are not counted in NR_ANON_PAGES for now. */ > + if (unlikely(PageHuge(page))) > + return; > > /* > - * Hugepages are not counted in NR_ANON_PAGES nor NR_FILE_MAPPED > - * and not charged by memcg for now. > - * > * We use the irq-unsafe __{inc|mod}_zone_page_stat because > * these counters are not modified in interrupt context, and > - * these counters are not modified in interrupt context, and > * pte lock(a spinlock) is held, which implies preemption disabled. > */ > - if (unlikely(PageHuge(page))) > - goto out; > - if (anon) { > - if (PageTransHuge(page)) > - __dec_zone_page_state(page, > - NR_ANON_TRANSPARENT_HUGEPAGES); > - __mod_zone_page_state(page_zone(page), NR_ANON_PAGES, > - -hpage_nr_pages(page)); > - } else { > - __dec_zone_page_state(page, NR_FILE_MAPPED); > - mem_cgroup_dec_page_stat(memcg, MEM_CGROUP_STAT_FILE_MAPPED); > - } > + if (PageTransHuge(page)) > + __dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES); > + > + __mod_zone_page_state(page_zone(page), NR_ANON_PAGES, > + -hpage_nr_pages(page)); > + > if (unlikely(PageMlocked(page))) > clear_page_mlock(page); > + > /* > * It would be tidy to reset the PageAnon mapping here, > * but that might overwrite a racing page_add_anon_rmap > @@ -1111,9 +1128,6 @@ void page_remove_rmap(struct page *page) > * Leaving it set also helps swapoff to reinstate ptes > * faster for those pages still in swapcache. > */ > -out: > - if (!anon) > - mem_cgroup_end_page_stat(memcg, locked, flags); > } > > /* > -- > 2.1.2 > -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
