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Commit 0f074658 authored by Minchan Kim's avatar Minchan Kim Committed by Linus Torvalds
Browse files

mm, THP, swap: move anonymous THP split logic to vmscan 

The add_to_swap aims to allocate swap_space(ie, swap slot and swapcache)
so if it fails due to lack of space in case of THP or something(hdd swap
but tries THP swapout) *caller* rather than add_to_swap itself should
split the THP page and retry it with base page which is more natural.

Link: http://lkml.kernel.org/r/20170515112522.32457-4-ying.huang@intel.com


Signed-off-by: default avatarMinchan Kim <minchan@kernel.org>
Signed-off-by: default avatar"Huang, Ying" <ying.huang@intel.com>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Shaohua Li <shli@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 75f6d6d2

include/linux/swap.h

+2 −2
Original line number Diff line number Diff line
@@ -353,7 +353,7 @@ extern struct address_space *swapper_spaces[]; 
		>> SWAP_ADDRESS_SPACE_SHIFT])

extern unsigned long total_swapcache_pages(void);

extern void show_swap_cache_info(void);

extern int add_to_swap(struct page *, struct list_head *list);

extern int add_to_swap(struct page *page);

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 *);
@@ -473,7 +473,7 @@ static inline struct page *lookup_swap_cache(swp_entry_t swp) 
	return NULL;

}



static inline int add_to_swap(struct page *page, struct list_head *list)

static inline int add_to_swap(struct page *page)

{

	return 0;

}

mm/swap_state.c

+6 −17
Original line number Diff line number Diff line
@@ -184,7 +184,7 @@ void __delete_from_swap_cache(struct page *page) 
 * Allocate swap space for the page and add the page to the

 * swap cache.  Caller needs to hold the page lock. 

 */

int add_to_swap(struct page *page, struct list_head *list)

int add_to_swap(struct page *page)

{

	swp_entry_t entry;

	int err;
@@ -192,12 +192,12 @@ int add_to_swap(struct page *page, struct list_head *list) 
	VM_BUG_ON_PAGE(!PageLocked(page), page);

	VM_BUG_ON_PAGE(!PageUptodate(page), page);



retry:

	entry = get_swap_page(page);

	if (!entry.val)

		goto fail;

		return 0;



	if (mem_cgroup_try_charge_swap(page, entry))

		goto fail_free;

		goto fail;



	/*

	 * Radix-tree node allocations from PF_MEMALLOC contexts could
@@ -218,23 +218,12 @@ int add_to_swap(struct page *page, struct list_head *list) 
		 * add_to_swap_cache() doesn't return -EEXIST, so we can safely

		 * clear SWAP_HAS_CACHE flag.

		 */

		goto fail_free;



	if (PageTransHuge(page)) {

		err = split_huge_page_to_list(page, list);

		if (err) {

			delete_from_swap_cache(page);

			return 0;

		}

	}

		goto fail;



	return 1;



fail_free:

	put_swap_page(page, entry);

fail:

	if (PageTransHuge(page) && !split_huge_page_to_list(page, list))

		goto retry;

	put_swap_page(page, entry);

	return 0;

}

mm/vmscan.c

+16 −1
Original line number Diff line number Diff line
@@ -1125,8 +1125,23 @@ static unsigned long shrink_page_list(struct list_head *page_list, 
		    !PageSwapCache(page)) {

			if (!(sc->gfp_mask & __GFP_IO))

				goto keep_locked;

			if (!add_to_swap(page, page_list))

			if (!add_to_swap(page)) {

				if (!PageTransHuge(page))

					goto activate_locked;

				/* Split THP and swap individual base pages */

				if (split_huge_page_to_list(page, page_list))

					goto activate_locked;

				if (!add_to_swap(page))

					goto activate_locked;

			}



			/* XXX: We don't support THP writes */

			if (PageTransHuge(page) &&

				  split_huge_page_to_list(page, page_list)) {

				delete_from_swap_cache(page);

				goto activate_locked;

			}



			may_enter_fs = 1;



			/* Adding to swap updated mapping */