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author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2016-03-15 14:57:30 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-03-15 16:55:16 -0700 |
commit | 8df651c7059e7980f08430d4ebbd134b046657ee (patch) | |
tree | e5a53184414736b25e4436ff30aa28360573d2bb /mm | |
parent | 88193f7ce6657ec4197b1f26b73b37197373b8e6 (diff) | |
download | linux-8df651c7059e7980f08430d4ebbd134b046657ee.tar.gz linux-8df651c7059e7980f08430d4ebbd134b046657ee.tar.bz2 linux-8df651c7059e7980f08430d4ebbd134b046657ee.zip |
thp: cleanup split_huge_page()
After one of bugfixes to freeze_page(), we don't have freezed pages in
rmap, therefore mapcount of all subpages of freezed THP is zero. And we
have assert for that.
Let's drop code which deal with non-zero mapcount of subpages.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r-- | mm/huge_memory.c | 20 |
1 files changed, 7 insertions, 13 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index e10a4fee88d2..1ea21e203a70 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -3220,28 +3220,26 @@ static void unfreeze_page(struct anon_vma *anon_vma, struct page *page) } } -static int __split_huge_page_tail(struct page *head, int tail, +static void __split_huge_page_tail(struct page *head, int tail, struct lruvec *lruvec, struct list_head *list) { - int mapcount; struct page *page_tail = head + tail; - mapcount = atomic_read(&page_tail->_mapcount) + 1; + VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail); VM_BUG_ON_PAGE(atomic_read(&page_tail->_count) != 0, page_tail); /* * tail_page->_count is zero and not changing from under us. But * get_page_unless_zero() may be running from under us on the - * tail_page. If we used atomic_set() below instead of atomic_add(), we + * tail_page. If we used atomic_set() below instead of atomic_inc(), we * would then run atomic_set() concurrently with * get_page_unless_zero(), and atomic_set() is implemented in C not * using locked ops. spin_unlock on x86 sometime uses locked ops * because of PPro errata 66, 92, so unless somebody can guarantee * atomic_set() here would be safe on all archs (and not only on x86), - * it's safer to use atomic_add(). + * it's safer to use atomic_inc(). */ - atomic_add(mapcount + 1, &page_tail->_count); - + atomic_inc(&page_tail->_count); page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; page_tail->flags |= (head->flags & @@ -3275,8 +3273,6 @@ static int __split_huge_page_tail(struct page *head, int tail, page_tail->index = head->index + tail; page_cpupid_xchg_last(page_tail, page_cpupid_last(head)); lru_add_page_tail(head, page_tail, lruvec, list); - - return mapcount; } static void __split_huge_page(struct page *page, struct list_head *list) @@ -3284,7 +3280,7 @@ static void __split_huge_page(struct page *page, struct list_head *list) struct page *head = compound_head(page); struct zone *zone = page_zone(head); struct lruvec *lruvec; - int i, tail_mapcount; + int i; /* prevent PageLRU to go away from under us, and freeze lru stats */ spin_lock_irq(&zone->lru_lock); @@ -3293,10 +3289,8 @@ static void __split_huge_page(struct page *page, struct list_head *list) /* complete memcg works before add pages to LRU */ mem_cgroup_split_huge_fixup(head); - tail_mapcount = 0; for (i = HPAGE_PMD_NR - 1; i >= 1; i--) - tail_mapcount += __split_huge_page_tail(head, i, lruvec, list); - atomic_sub(tail_mapcount, &head->_count); + __split_huge_page_tail(head, i, lruvec, list); ClearPageCompound(head); spin_unlock_irq(&zone->lru_lock); |