diff options
| author | Andrea Arcangeli <aarcange@redhat.com> | 2011-11-02 13:37:25 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-11-02 16:06:58 -0700 |
| commit | 220a2eb228d032acde60e9fd044ca802706ff583 (patch) | |
| tree | a764d37aace07cf5a9fa2c1e5b7f81662dfee7ae /arch/s390 | |
| parent | cf592bf768c4fa40282b8fce58a80820065de2cb (diff) | |
s390: gup_huge_pmd() support THP tail recounting
Up to this point the code assumed old refcounting for hugepages (pre-thp).
This updates the code directly to the thp mapcount tail page refcounting.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/s390')
| -rw-r--r-- | arch/s390/mm/gup.c | 24 |
1 files changed, 23 insertions, 1 deletions
diff --git a/arch/s390/mm/gup.c b/arch/s390/mm/gup.c index 45b405ca2567..668dda964f20 100644 --- a/arch/s390/mm/gup.c +++ b/arch/s390/mm/gup.c @@ -48,11 +48,22 @@ static inline int gup_pte_range(pmd_t *pmdp, pmd_t pmd, unsigned long addr, return 1; } +static inline void get_huge_page_tail(struct page *page) +{ + /* + * __split_huge_page_refcount() cannot run + * from under us. + */ + VM_BUG_ON(page_mapcount(page) < 0); + VM_BUG_ON(atomic_read(&page->_count) != 0); + atomic_inc(&page->_mapcount); +} + static inline int gup_huge_pmd(pmd_t *pmdp, pmd_t pmd, unsigned long addr, unsigned long end, int write, struct page **pages, int *nr) { unsigned long mask, result; - struct page *head, *page; + struct page *head, *page, *tail; int refs; result = write ? 0 : _SEGMENT_ENTRY_RO; @@ -64,6 +75,7 @@ static inline int gup_huge_pmd(pmd_t *pmdp, pmd_t pmd, unsigned long addr, refs = 0; head = pmd_page(pmd); page = head + ((addr & ~PMD_MASK) >> PAGE_SHIFT); + tail = page; do { VM_BUG_ON(compound_head(page) != head); pages[*nr] = page; @@ -81,6 +93,16 @@ static inline int gup_huge_pmd(pmd_t *pmdp, pmd_t pmd, unsigned long addr, *nr -= refs; while (refs--) put_page(head); + } else { + /* + * Any tail page need their mapcount reference taken + * before we return. + */ + while (refs--) { + if (PageTail(tail)) + get_huge_page_tail(tail); + tail++; + } } return 1; |