Commit 3526741f authored by Andrea Arcangeli's avatar Andrea Arcangeli Committed by Linus Torvalds
Browse files

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: default avatarAndrea 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 85964684
......@@ -385,12 +385,23 @@ follow_huge_pmd(struct mm_struct *mm, unsigned long address,
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,
unsigned long end, int write, struct page **pages, int *nr)
{
unsigned long mask;
unsigned long pte_end;
struct page *head, *page;
struct page *head, *page, *tail;
pte_t pte;
int refs;
......@@ -413,6 +424,7 @@ static noinline int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long add
head = pte_page(pte);
page = head + ((addr & (sz-1)) >> PAGE_SHIFT);
tail = page;
do {
VM_BUG_ON(compound_head(page) != head);
pages[*nr] = page;
......@@ -431,6 +443,16 @@ static noinline int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long add
*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;
......
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment