diff options
| -rw-r--r-- | mm/hugetlb.c | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 691f2264a6c..0b7656e804d 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -696,8 +696,22 @@ static void prep_compound_gigantic_page(struct page *page, unsigned long order) /* we rely on prep_new_huge_page to set the destructor */ set_compound_order(page, order); __SetPageHead(page); + __ClearPageReserved(page); for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) { __SetPageTail(p); + /* + * For gigantic hugepages allocated through bootmem at + * boot, it's safer to be consistent with the not-gigantic + * hugepages and clear the PG_reserved bit from all tail pages + * too. Otherwse drivers using get_user_pages() to access tail + * pages may get the reference counting wrong if they see + * PG_reserved set on a tail page (despite the head page not + * having PG_reserved set). Enforcing this consistency between + * head and tail pages allows drivers to optimize away a check + * on the head page when they need know if put_page() is needed + * after get_user_pages(). + */ + __ClearPageReserved(p); set_page_count(p, 0); p->first_page = page; } @@ -1330,9 +1344,9 @@ static void __init gather_bootmem_prealloc(void) #else page = virt_to_page(m); #endif - __ClearPageReserved(page); WARN_ON(page_count(page) != 1); prep_compound_huge_page(page, h->order); + WARN_ON(PageReserved(page)); prep_new_huge_page(h, page, page_to_nid(page)); /* * If we had gigantic hugepages allocated at boot time, we need |