Unverified Commit ab9b23cd authored by openeuler-ci-bot's avatar openeuler-ci-bot Committed by Gitee
Browse files

!5999 mm/swap: fix race when skipping swapcache 

Merge Pull Request from: @ci-robot 
 
PR sync from: Jinjiang Tu <tujinjiang@huawei.com>
https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/message/OX2HMK6Z37VOW6ZULRKYBIZ76FEAETRG/ 
 
https://gitee.com/src-openeuler/kernel/issues/I9E2M2 
 
Link:https://gitee.com/openeuler/kernel/pulls/5999

 

Reviewed-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: default avatarLiu YongQiang <liuyongqiang13@huawei.com>
Signed-off-by: default avatarZhang Changzhong <zhangchangzhong@huawei.com>
parents 49177142 0cf13f3b

include/linux/swap.h

+5 −0
Original line number Diff line number Diff line
@@ -468,6 +468,7 @@ extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t); 
extern int __add_to_swap_cache(struct page *page, swp_entry_t entry);

extern void __delete_from_swap_cache(struct page *);

extern void delete_from_swap_cache(struct page *);

void swapcache_clear(struct swap_info_struct *si, swp_entry_t entry);

extern void free_page_and_swap_cache(struct page *);

extern void free_pages_and_swap_cache(struct page **, int);

extern struct page *lookup_swap_cache(swp_entry_t entry,
@@ -609,6 +610,10 @@ static inline int swap_writepage(struct page *p, struct writeback_control *wbc) 
	return 0;

}



static inline void swapcache_clear(struct swap_info_struct *si, swp_entry_t entry)

{

}



static inline struct page *lookup_swap_cache(swp_entry_t swp,

					     struct vm_area_struct *vma,

					     unsigned long addr)

mm/memory.c

+22 −1
Original line number Diff line number Diff line
@@ -2919,6 +2919,8 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) 
	struct vm_area_struct *vma = vmf->vma;

	struct page *page = NULL, *swapcache;

	struct mem_cgroup *memcg;

	struct swap_info_struct *si = NULL;

	bool need_clear_cache = false;

	swp_entry_t entry;

	pte_t pte;

	int locked;
@@ -2974,10 +2976,24 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) 
	swapcache = page;



	if (!page) {

		struct swap_info_struct *si = swp_swap_info(entry);

		si = swp_swap_info(entry);



		if (si->flags & SWP_SYNCHRONOUS_IO &&

				__swap_count(entry) == 1) {

			/*

			 * Prevent parallel swapin from proceeding with

			 * the cache flag. Otherwise, another thread may

			 * finish swapin first, free the entry, and swapout

			 * reusing the same entry. It's undetectable as

			 * pte_same() returns true due to entry reuse.

			 */

			if (swapcache_prepare(entry)) {

				/* Relax a bit to prevent rapid repeated page faults */

				schedule_timeout_uninterruptible(1);

				goto out;

			}

			need_clear_cache = true;



			/* skip swapcache */

			page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,

							vmf->address);
@@ -3133,6 +3149,9 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) 
unlock:

	pte_unmap_unlock(vmf->pte, vmf->ptl);

out:

	/* Clear the swap cache pin for direct swapin after PTL unlock */

	if (need_clear_cache)

		swapcache_clear(si, entry);

	return ret;

out_nomap:

	mem_cgroup_cancel_charge(page, memcg, false);
@@ -3145,6 +3164,8 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) 
		unlock_page(swapcache);

		put_page(swapcache);

	}

	if (need_clear_cache)

		swapcache_clear(si, entry);

	return ret;

}

mm/swapfile.c

+13 −0
Original line number Diff line number Diff line
@@ -3590,6 +3590,19 @@ int swapcache_prepare(swp_entry_t entry) 
	return __swap_duplicate(entry, SWAP_HAS_CACHE);

}



void swapcache_clear(struct swap_info_struct *si, swp_entry_t entry)

{

	struct swap_cluster_info *ci;

	unsigned long offset = swp_offset(entry);

	unsigned char usage;



	ci = lock_cluster_or_swap_info(si, offset);

	usage = __swap_entry_free_locked(si, offset, SWAP_HAS_CACHE);

	unlock_cluster_or_swap_info(si, ci);

	if (!usage)

		free_swap_slot(entry);

}



struct swap_info_struct *swp_swap_info(swp_entry_t entry)

{

	return swap_type_to_swap_info(swp_type(entry));