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powerpc: gup_hugepte() support THP based 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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrea Arcangeli 2011-11-02 13:37:15 -07:00 committed by Linus Torvalds
parent 8596468487
commit 3526741f09
1 changed files with 23 additions and 1 deletions
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24
arch/powerpc/mm/hugetlbpage.c
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@ -385,12 +385,23 @@ follow_huge_pmd(struct mm_struct *mm, unsigned long address,
return NULL; return NULL;
} }
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 noinline int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr, static noinline int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
unsigned long end, int write, struct page **pages, int *nr) unsigned long end, int write, struct page **pages, int *nr)
{ {
unsigned long mask; unsigned long mask;
unsigned long pte_end; unsigned long pte_end;
struct page *head, *page; struct page *head, *page, *tail;
pte_t pte; pte_t pte;
int refs; int refs;
@ -413,6 +424,7 @@ static noinline int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long add
head = pte_page(pte); head = pte_page(pte);
page = head + ((addr & (sz-1)) >> PAGE_SHIFT); page = head + ((addr & (sz-1)) >> PAGE_SHIFT);
tail = page;
do { do {
VM_BUG_ON(compound_head(page) != head); VM_BUG_ON(compound_head(page) != head);
pages[*nr] = page; pages[*nr] = page;
@ -431,6 +443,16 @@ static noinline int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long add
*nr -= refs; *nr -= refs;
while (refs--) while (refs--)
put_page(head); 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; return 1;