Unverified Commit dc052c8e authored by openeuler-ci-bot's avatar openeuler-ci-bot Committed by Gitee
Browse files

!9131 mm: swap: fix race between free_swap_and_cache() and swapoff() 

Merge Pull Request from: @ci-robot 
 
PR sync from: Jinjiang Tu <tujinjiang@huawei.com>
https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/message/TA2HE5DKJBGC3S7FOPGMKNHPRXWCXNTJ/ 
 
https://gitee.com/src-openeuler/kernel/issues/I9L4RJ 
 
Link:https://gitee.com/openeuler/kernel/pulls/9131

 

Reviewed-by: default avatarJialin Zhang <zhangjialin11@huawei.com>
Signed-off-by: default avatarJialin Zhang <zhangjialin11@huawei.com>
parents 33906cb8 1d94cc34

mm/swapfile.c

+12 −1
Original line number Diff line number Diff line
@@ -1373,6 +1373,11 @@ static unsigned char __swap_entry_free_locked(struct swap_info_struct *p, 
}



/*

 * Note that when only holding the PTL, swapoff might succeed immediately

 * after freeing a swap entry. Therefore, immediately after

 * __swap_entry_free(), the swap info might become stale and should not

 * be touched without a prior get_swap_device().

 *

 * Check whether swap entry is valid in the swap device.  If so,

 * return pointer to swap_info_struct, and keep the swap entry valid

 * via preventing the swap device from being swapoff, until
@@ -1899,13 +1904,19 @@ int free_swap_and_cache(swp_entry_t entry) 
	if (non_swap_entry(entry))

		return 1;



	p = _swap_info_get(entry);

	p = get_swap_device(entry);

	if (p) {

		if (WARN_ON(data_race(!p->swap_map[swp_offset(entry)]))) {

			put_swap_device(p);

			return 0;

		}



		count = __swap_entry_free(p, entry);

		if (count == SWAP_HAS_CACHE &&

		    !swap_page_trans_huge_swapped(p, entry))

			__try_to_reclaim_swap(p, swp_offset(entry),

					      TTRS_UNMAPPED | TTRS_FULL);

		put_swap_device(p);

	}

	return p != NULL;

}