>I completely agree with Andrew's suggestion that you move the code
>from mm/internal.h to its sole callsite in mm/rmap.c; but I much
>prefer his "probably better ... open-coding its logic into
>page_add_new_anon_rmap()".
>
>That saves you from having to dream up a satisfactory alternative name,
>and a lengthy comment, and let's everybody see just what's going on.
Hi, also thanks for the detailed comments!!!
Yes, I also agree. But I just saw that mlocked_vma_newpage() is used
as a test stament in page_add_new_anon_rmap(), like:
if (!mlocked_vma_newpage())
...
else
...
It is quite clear code logic for reading, so I think it is appropriate
to still make it a function. But that's OK, I've folded it into
page_add_new_anon_rmap() in the new patch, see below.
>The function-in-internal.h thing dates from an interim in which,
>running short of page flags, we were not confident that we wanted
>to dedicate one to PageMlocked: not all configs had it and internal.h
>was somewhere to hide the #ifdefs. Well, PageMlocked is there only
>when CONFIG_MMU, but mm/rmap.c is only built for CONFIG_MMU anyway.
>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.
Thanks for telling me this, which be not be learned from code.
-----<8-----
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.
Suggested-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Suggested-by: Hugh Dickins <hughd@xxxxxxxxxx>
Signed-off-by: Jianyu Zhan <nasa4836@xxxxxxxxx>
---
mm/internal.h | 31 -------------------------------
mm/rmap.c | 22 +++++++++++++++++++---
2 files changed, 19 insertions(+), 34 deletions(-)
diff --git a/mm/internal.h b/mm/internal.h
index 7140c9b..29f3dc8 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -184,33 +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
- * 1. this counter is not modified in interrupt context, and
- * 2. pte lock is held, and this a newpage, which is initially
- * only visible via the pagetables. So this would exclude
- * racy processes from preemting us and to modify it.
- */
- __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);
@@ -252,10 +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 0700253..b7bf67b 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1030,11 +1030,27 @@ 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
+ * 1. this counter is not modified in interrupt context, and
+ * 2. pte lock is held, and this a newpage, which is initially
+ * only visible via the pagetables. So this would exclude
+ * racy processes from preemting us and to modify it.
+ */
+ __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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