| From 220a2eb228d032acde60e9fd044ca802706ff583 Mon Sep 17 00:00:00 2001 |
| From: Andrea Arcangeli <aarcange@redhat.com> |
| Date: Wed, 2 Nov 2011 13:37:25 -0700 |
| Subject: s390: gup_huge_pmd() support THP tail recounting |
| |
| From: Andrea Arcangeli <aarcange@redhat.com> |
| |
| commit 220a2eb228d032acde60e9fd044ca802706ff583 upstream. |
| |
| 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> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> |
| |
| --- |
| arch/s390/mm/gup.c | 24 +++++++++++++++++++++++- |
| 1 file changed, 23 insertions(+), 1 deletion(-) |
| |
| --- a/arch/s390/mm/gup.c |
| +++ b/arch/s390/mm/gup.c |
| @@ -48,11 +48,22 @@ static inline int gup_pte_range(pmd_t *p |
| 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 *pm |
| 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 *pm |
| *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; |