On Tue, 13 May 2014, Jianyu Zhan wrote:
> Andrew, since the previous patch
>
> [PATCH 1/3] mm: add comment for __mod_zone_page_stat
>
> is updated, update this one accordingly.
>
> -----<8-----
> From 9701fbdb3f9e7730b89780a5bf22effd1580cf35 Mon Sep 17 00:00:00 2001
> From: Jianyu Zhan <nasa4836@xxxxxxxxx>
> Date: Tue, 13 May 2014 01:48:01 +0800
> Subject: [PATCH] mm: fold mlocked_vma_newpage() into its only call site
>
> In previous commit(mm: use the light version __mod_zone_page_state in
> mlocked_vma_newpage()) a irq-unsafe __mod_zone_page_state is used.
> And as suggested by Andrew, to reduce the risks that new call sites
> incorrectly using mlocked_vma_newpage() without knowing they are adding
> racing, this patch folds mlocked_vma_newpage() into its only call site,
> page_add_new_anon_rmap, to make it open-cocded for people to know what
> is going on.
>
> Suggested-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Suggested-by: Hugh Dickins <hughd@xxxxxxxxxx>
> Signed-off-by: Jianyu Zhan <nasa4836@xxxxxxxxx>
Acked-by: Hugh Dickins <hughd@xxxxxxxxxx>
Yes, much better, thanks: you made and commented the __ change in the
previous patch, and now you just do the move. I'd have probably moved
the VM_BUG_ON_PAGE(PageLRU,) up to the top of page_add_new_anon_rmap(),
where we already document some expectations on entry (or else removed it
completely, given that lru_cache_add() does the same); but that's a nit,
no need to make further change now.
> ---
> mm/internal.h | 29 -----------------------------
> mm/rmap.c | 20 +++++++++++++++++---
> 2 files changed, 17 insertions(+), 32 deletions(-)
>
> diff --git a/mm/internal.h b/mm/internal.h
> index d6a4868..29f3dc8 100644
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -184,31 +184,6 @@ static inline void munlock_vma_pages_all(struct vm_area_struct *vma)
> }
>
> /*
> - * Called only in fault path, to determine if a new page is being
> - * mapped into a LOCKED vma. If it is, mark page as mlocked.
> - */
> -static inline int mlocked_vma_newpage(struct vm_area_struct *vma,
> - struct page *page)
> -{
> - VM_BUG_ON_PAGE(PageLRU(page), page);
> -
> - if (likely((vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) != VM_LOCKED))
> - return 0;
> -
> - if (!TestSetPageMlocked(page)) {
> - /*
> - * 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);
> - }
> - return 1;
> -}
> -
> -/*
> * must be called with vma's mmap_sem held for read or write, and page locked.
> */
> extern void mlock_vma_page(struct page *page);
> @@ -250,10 +225,6 @@ extern unsigned long vma_address(struct page *page,
> struct vm_area_struct *vma);
> #endif
> #else /* !CONFIG_MMU */
> -static inline int mlocked_vma_newpage(struct vm_area_struct *v, struct page *p)
> -{
> - return 0;
> -}
> static inline void clear_page_mlock(struct page *page) { }
> static inline void mlock_vma_page(struct page *page) { }
> static inline void mlock_migrate_page(struct page *new, struct page *old) { }
> diff --git a/mm/rmap.c b/mm/rmap.c
> index fa73194..386b78f 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -1029,11 +1029,25 @@ void page_add_new_anon_rmap(struct page *page,
> __mod_zone_page_state(page_zone(page), NR_ANON_PAGES,
> hpage_nr_pages(page));
> __page_set_anon_rmap(page, vma, address, 1);
> - if (!mlocked_vma_newpage(vma, page)) {
> +
> + VM_BUG_ON_PAGE(PageLRU(page), page);
> + if (likely((vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) != VM_LOCKED)) {
> SetPageActive(page);
> lru_cache_add(page);
> - } else
> - add_page_to_unevictable_list(page);
> + return;
> + }
> +
> + if (!TestSetPageMlocked(page)) {
> + /*
> + * 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);
> + }
> + add_page_to_unevictable_list(page);
> }
>
> /**
> --
> 2.0.0-rc1
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