Commit 6326fec1 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Linus Torvalds
Browse files

mm: Use owner_priv bit for PageSwapCache, valid when PageSwapBacked 



A page is not added to the swap cache without being swap backed,
so PageSwapBacked mappings can use PG_owner_priv_1 for PageSwapCache.

Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Acked-by: default avatarHugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Bob Peterson <rpeterso@redhat.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Andrew Lutomirski <luto@kernel.org>
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7c0f6ba6

include/linux/page-flags.h

+16 −8
Original line number Diff line number Diff line
@@ -87,7 +87,6 @@ enum pageflags { 
	PG_private_2,		/* If pagecache, has fs aux data */

	PG_writeback,		/* Page is under writeback */

	PG_head,		/* A head page */

	PG_swapcache,		/* Swap page: swp_entry_t in private */

	PG_mappedtodisk,	/* Has blocks allocated on-disk */

	PG_reclaim,		/* To be reclaimed asap */

	PG_swapbacked,		/* Page is backed by RAM/swap */
@@ -110,6 +109,9 @@ enum pageflags { 
	/* Filesystems */

	PG_checked = PG_owner_priv_1,



	/* SwapBacked */

	PG_swapcache = PG_owner_priv_1,	/* Swap page: swp_entry_t in private */



	/* Two page bits are conscripted by FS-Cache to maintain local caching

	 * state.  These bits are set on pages belonging to the netfs's inodes

	 * when those inodes are being locally cached.
@@ -314,7 +316,13 @@ PAGEFLAG_FALSE(HighMem) 
#endif



#ifdef CONFIG_SWAP

PAGEFLAG(SwapCache, swapcache, PF_NO_COMPOUND)

static __always_inline int PageSwapCache(struct page *page)

{

	return PageSwapBacked(page) && test_bit(PG_swapcache, &page->flags);



}

SETPAGEFLAG(SwapCache, swapcache, PF_NO_COMPOUND)

CLEARPAGEFLAG(SwapCache, swapcache, PF_NO_COMPOUND)

#else

PAGEFLAG_FALSE(SwapCache)

#endif
@@ -705,7 +713,7 @@ static inline void ClearPageSlabPfmemalloc(struct page *page) 
	(1UL << PG_lru		| 1UL << PG_locked	|	\

	 1UL << PG_private	| 1UL << PG_private_2	|	\

	 1UL << PG_writeback	| 1UL << PG_reserved	|	\

	 1UL << PG_slab	 | 1UL << PG_swapcache | 1UL << PG_active | \

	 1UL << PG_slab		| 1UL << PG_active 	|	\

	 1UL << PG_unevictable	| __PG_MLOCKED)



/*

include/trace/events/mmflags.h

+0 −1
Original line number Diff line number Diff line
@@ -95,7 +95,6 @@ 
	{1UL << PG_private_2,		"private_2"	},		\

	{1UL << PG_writeback,		"writeback"	},		\

	{1UL << PG_head,		"head"		},		\

	{1UL << PG_swapcache,		"swapcache"	},		\

	{1UL << PG_mappedtodisk,	"mappedtodisk"	},		\

	{1UL << PG_reclaim,		"reclaim"	},		\

	{1UL << PG_swapbacked,		"swapbacked"	},		\

mm/memory-failure.c

+1 −3
Original line number Diff line number Diff line
@@ -764,12 +764,11 @@ static int me_huge_page(struct page *p, unsigned long pfn) 
 */



#define dirty		(1UL << PG_dirty)

#define sc		(1UL << PG_swapcache)

#define sc		((1UL << PG_swapcache) | (1UL << PG_swapbacked))

#define unevict		(1UL << PG_unevictable)

#define mlock		(1UL << PG_mlocked)

#define writeback	(1UL << PG_writeback)

#define lru		(1UL << PG_lru)

#define swapbacked	(1UL << PG_swapbacked)

#define head		(1UL << PG_head)

#define slab		(1UL << PG_slab)

#define reserved	(1UL << PG_reserved)
@@ -819,7 +818,6 @@ static struct page_state { 
#undef mlock

#undef writeback

#undef lru

#undef swapbacked

#undef head

#undef slab

#undef reserved

mm/migrate.c

+8 −6
Original line number Diff line number Diff line
@@ -466,14 +466,16 @@ int migrate_page_move_mapping(struct address_space *mapping, 
	 */

	newpage->index = page->index;

	newpage->mapping = page->mapping;

	if (PageSwapBacked(page))

		__SetPageSwapBacked(newpage);



	get_page(newpage);	/* add cache reference */

	if (PageSwapBacked(page)) {

		__SetPageSwapBacked(newpage);

		if (PageSwapCache(page)) {

			SetPageSwapCache(newpage);

			set_page_private(newpage, page_private(page));

		}

	} else {

		VM_BUG_ON_PAGE(PageSwapCache(page), page);

	}



	/* Move dirty while page refs frozen and newpage not yet exposed */

	dirty = PageDirty(page);

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