Subject: + mm-use-the-light-version-__mod_zone_page_state-in-mlocked_vma_newpage.patch added to -mm tree To: nasa4836@xxxxxxxxx,akpm@xxxxxxxxxxxxxxxxxxxx,cl@xxxxxxxxx,hughd@xxxxxxxxxx From: akpm@xxxxxxxxxxxxxxxxxxxx Date: Mon, 12 May 2014 13:50:08 -0700 The patch titled Subject: mm: use the light version __mod_zone_page_state in mlocked_vma_newpage() has been added to the -mm tree. Its filename is mm-use-the-light-version-__mod_zone_page_state-in-mlocked_vma_newpage.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/mm-use-the-light-version-__mod_zone_page_state-in-mlocked_vma_newpage.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/mm-use-the-light-version-__mod_zone_page_state-in-mlocked_vma_newpage.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Jianyu Zhan <nasa4836@xxxxxxxxx> Subject: mm: use the light version __mod_zone_page_state in mlocked_vma_newpage() mlocked_vma_newpage() is called with pte lock held(a spinlock), which implies preemtion disabled, and the vm stat counter is not modified from interrupt context, so we need not use an irq-safe mod_zone_page_state() here, using a light-weight version __mod_zone_page_state() would be OK. This patch also documents __mod_zone_page_state() and some of its callsites. The comment above __mod_zone_page_state() is from Hugh Dickins, and acked by Christoph. Most credits to Hugh and Christoph for the clarification on the usage of the __mod_zone_page_state(). Suggested-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx> Reviewed-by: Christoph Lameter <cl@xxxxxxxxx> Signed-off-by: Jianyu Zhan <nasa4836@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/internal.h | 7 ++++++- mm/rmap.c | 9 +++++++++ mm/vmstat.c | 4 +++- 3 files changed, 18 insertions(+), 2 deletions(-) diff -puN mm/internal.h~mm-use-the-light-version-__mod_zone_page_state-in-mlocked_vma_newpage mm/internal.h --- a/mm/internal.h~mm-use-the-light-version-__mod_zone_page_state-in-mlocked_vma_newpage +++ a/mm/internal.h @@ -201,7 +201,12 @@ static inline int mlocked_vma_newpage(st return 0; if (!TestSetPageMlocked(page)) { - mod_zone_page_state(page_zone(page), NR_MLOCK, + /* + * We use the irq-unsafe __mod_zone_page_stat because + * this counter is not modified from interrupt context, and the + * pte lock is held(spinlock), which implies preemption disabled. + */ + __mod_zone_page_state(page_zone(page), NR_MLOCK, hpage_nr_pages(page)); count_vm_event(UNEVICTABLE_PGMLOCKED); } diff -puN mm/rmap.c~mm-use-the-light-version-__mod_zone_page_state-in-mlocked_vma_newpage mm/rmap.c --- a/mm/rmap.c~mm-use-the-light-version-__mod_zone_page_state-in-mlocked_vma_newpage +++ a/mm/rmap.c @@ -982,6 +982,11 @@ void do_page_add_anon_rmap(struct page * { int first = atomic_inc_and_test(&page->_mapcount); if (first) { + /* + * We use the irq-unsafe __{inc|mod}_zone_page_stat because + * these counters are not modified from interrupt context, and + * pte lock(a spinlock) is held, which implies preemption disabled. + */ if (PageTransHuge(page)) __inc_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES); @@ -1073,6 +1078,10 @@ void page_remove_rmap(struct page *page) /* * 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 from interrupt context, and + * pte lock(a spinlock) is held, which implies preemption disabled. */ if (unlikely(PageHuge(page))) goto out; diff -puN mm/vmstat.c~mm-use-the-light-version-__mod_zone_page_state-in-mlocked_vma_newpage mm/vmstat.c --- a/mm/vmstat.c~mm-use-the-light-version-__mod_zone_page_state-in-mlocked_vma_newpage +++ a/mm/vmstat.c @@ -207,7 +207,9 @@ void set_pgdat_percpu_threshold(pg_data_ } /* - * For use when we know that interrupts are disabled. + * For use when we know that interrupts are disabled, + * or when we know that preemption is disabled and that + * particular counter cannot be updated from interrupt context. */ void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item, int delta) _ Patches currently in -mm which might be from nasa4836@xxxxxxxxx are mm-swapc-clean-up-lru_cache_add-functions.patch mm-swapc-introduce-put_refcounted_compound_page-helpers-for-spliting-put_compound_page.patch mm-swapc-split-put_compound_page-function.patch mm-introdule-compound_head_by_tail.patch mm-memcontrol-clean-up-memcg-zoneinfo-lookup.patch mm-memcontrol-remove-unnecessary-memcg-argument-from-soft-limit-functions.patch mm-use-the-light-version-__mod_zone_page_state-in-mlocked_vma_newpage.patch mm-use-a-light-weight-__mod_zone_page_state-in-mlocked_vma_newpage.patch linux-next.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html