Commit de98c7af authored by chenrenhui's avatar chenrenhui
Browse files

etmem : fix page_ref count leak and head missing useing problem 

euleros inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/IAXJCE


CVE: NA

----------------------------------------------------

In the etmem swap process, use get_page_from_vaddr to obtain
the page and add the page reference counting.

If a page does not meet the recycling criteria,
release the reference counting of the page.

In the add_page_for_swap process, if the input page is the
middle page of a compound page, head and page cannot be
used together.

Instead, head must be used as the input parameter.

Fixes: 8a655676 ("memig: add memig-swap feature to openEuler")
Signed-off-by: default avatarchenrenhui <chenrenhui1@huawei.com>
parent b61a367a

fs/proc/etmem_swap.c

+2 −0
Original line number Diff line number Diff line
@@ -70,6 +70,8 @@ static ssize_t swap_pages_write(struct file *file, const char __user *buf, 
			continue;



		add_page_for_swap(page, &pagelist);

		/* release the ref count we get from the get_page_from_vaddr interface */

		put_page(page);

	}



	if (!list_empty(&pagelist))

mm/vmscan.c

+6 −11
Original line number Diff line number Diff line
@@ -4623,7 +4623,6 @@ EXPORT_SYMBOL_GPL(check_move_unevictable_pages); 
#ifdef CONFIG_ETMEM

int add_page_for_swap(struct page *page, struct list_head *pagelist)

{

	int err = -EBUSY;

	struct page *head;



	/* If the page is mapped by more than one process, do not swap it */
@@ -4634,19 +4633,15 @@ int add_page_for_swap(struct page *page, struct list_head *pagelist) 
		return -EACCES;



	head = compound_head(page);

	err = isolate_lru_page(head);

	if (err) {

		put_page(page);

		return err;

	}

	put_page(page);

	if (PageUnevictable(page))

		putback_lru_page(page);

	if (isolate_lru_page(head))

		return -EBUSY;



	if (PageUnevictable(head))

		putback_lru_page(head);

	else

		list_add_tail(&head->lru, pagelist);



	err = 0;

	return err;

	return 0;

}

EXPORT_SYMBOL_GPL(add_page_for_swap);