Unverified Commit 0a28d59d authored by openeuler-ci-bot's avatar openeuler-ci-bot Committed by Gitee
Browse files

!5995 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/OOA6SREAEMWJD733ZA2BL6Z6ZCZRJWXH/ 
 
https://gitee.com/src-openeuler/kernel/issues/I9E2M2 
 
Link:https://gitee.com/openeuler/kernel/pulls/5995

 

Reviewed-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: default avatarJialin Zhang <zhangjialin11@huawei.com>
parents 25fdb6da 75acda4d

include/linux/swap.h

+5 −0
Original line number Diff line number Diff line
@@ -478,6 +478,7 @@ extern void __delete_from_swap_cache(struct page *page, 
extern void delete_from_swap_cache(struct page *);

extern void clear_shadow_from_swap_cache(int type, unsigned long begin,

				unsigned long end);

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,
@@ -638,6 +639,10 @@ 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

+20 −0
Original line number Diff line number Diff line
@@ -3387,6 +3387,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) 
	struct vm_area_struct *vma = vmf->vma;

	struct page *page = NULL, *swapcache;

	struct swap_info_struct *si = NULL;

	bool need_clear_cache = false;

	swp_entry_t entry;

	pte_t pte;

	int locked;
@@ -3444,6 +3445,20 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) 
	if (!page) {

		if (data_race(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);
@@ -3613,6 +3628,9 @@ 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);

	if (si)

		put_swap_device(si);

	return ret;
@@ -3626,6 +3644,8 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) 
		unlock_page(swapcache);

		put_page(swapcache);

	}

	if (need_clear_cache)

		swapcache_clear(si, entry);

	if (si)

		put_swap_device(si);

	return ret;

mm/swapfile.c

+13 −0
Original line number Diff line number Diff line
@@ -3688,6 +3688,19 @@ 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));