Commit 79789db0 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Linus Torvalds
Browse files

mm: Make copy_huge_page() always available 



Rewrite copy_huge_page() and move it into mm/util.c so it's always
available.  Fixes an exposure of uninitialised memory on configurations
with HUGETLB and UFFD enabled and MIGRATION disabled.

Fixes: 8cc5fcbb ("mm, hugetlb: fix racy resv_huge_pages underflow on UFFDIO_COPY")
Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: default avatarMike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent efdb6720

include/linux/migrate.h

+0 −5
Original line number Diff line number Diff line
@@ -51,7 +51,6 @@ extern int migrate_huge_page_move_mapping(struct address_space *mapping, 
				  struct page *newpage, struct page *page);

extern int migrate_page_move_mapping(struct address_space *mapping,

		struct page *newpage, struct page *page, int extra_count);

extern void copy_huge_page(struct page *dst, struct page *src);

#else



static inline void putback_movable_pages(struct list_head *l) {}
@@ -77,10 +76,6 @@ static inline int migrate_huge_page_move_mapping(struct address_space *mapping, 
{

	return -ENOSYS;

}



static inline void copy_huge_page(struct page *dst, struct page *src)

{

}

#endif /* CONFIG_MIGRATION */



#ifdef CONFIG_COMPACTION

include/linux/mm.h

+1 −0
Original line number Diff line number Diff line
@@ -906,6 +906,7 @@ void __put_page(struct page *page); 
void put_pages_list(struct list_head *pages);



void split_page(struct page *page, unsigned int order);

void copy_huge_page(struct page *dst, struct page *src);



/*

 * Compound pages have a destructor function.  Provide a

mm/migrate.c

+0 −48
Original line number Diff line number Diff line
@@ -536,54 +536,6 @@ int migrate_huge_page_move_mapping(struct address_space *mapping, 
	return MIGRATEPAGE_SUCCESS;

}



/*

 * Gigantic pages are so large that we do not guarantee that page++ pointer

 * arithmetic will work across the entire page.  We need something more

 * specialized.

 */

static void __copy_gigantic_page(struct page *dst, struct page *src,

				int nr_pages)

{

	int i;

	struct page *dst_base = dst;

	struct page *src_base = src;



	for (i = 0; i < nr_pages; ) {

		cond_resched();

		copy_highpage(dst, src);



		i++;

		dst = mem_map_next(dst, dst_base, i);

		src = mem_map_next(src, src_base, i);

	}

}



void copy_huge_page(struct page *dst, struct page *src)

{

	int i;

	int nr_pages;



	if (PageHuge(src)) {

		/* hugetlbfs page */

		struct hstate *h = page_hstate(src);

		nr_pages = pages_per_huge_page(h);



		if (unlikely(nr_pages > MAX_ORDER_NR_PAGES)) {

			__copy_gigantic_page(dst, src, nr_pages);

			return;

		}

	} else {

		/* thp page */

		BUG_ON(!PageTransHuge(src));

		nr_pages = thp_nr_pages(src);

	}



	for (i = 0; i < nr_pages; i++) {

		cond_resched();

		copy_highpage(dst + i, src + i);

	}

}



/*

 * Copy the page to its new location

 */

mm/util.c

+10 −0
Original line number Diff line number Diff line
@@ -731,6 +731,16 @@ int __page_mapcount(struct page *page) 
}

EXPORT_SYMBOL_GPL(__page_mapcount);



void copy_huge_page(struct page *dst, struct page *src)

{

	unsigned i, nr = compound_nr(src);



	for (i = 0; i < nr; i++) {

		cond_resched();

		copy_highpage(nth_page(dst, i), nth_page(src, i));

	}

}



int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS;

int sysctl_overcommit_ratio __read_mostly = 50;

unsigned long sysctl_overcommit_kbytes __read_mostly;