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: Nicholas Piggin <npiggin@gmail.com>
Acked-by: Hugh 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: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 74e4dda..a57c909 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -87,7 +87,6 @@
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 @@
/* 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 @@
#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
@@ -701,12 +709,12 @@
* Flags checked when a page is freed. Pages being freed should not have
* these flags set. It they are, there is a problem.
*/
-#define PAGE_FLAGS_CHECK_AT_FREE \
- (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_unevictable | __PG_MLOCKED)
+#define PAGE_FLAGS_CHECK_AT_FREE \
+ (1UL << PG_lru | 1UL << PG_locked | \
+ 1UL << PG_private | 1UL << PG_private_2 | \
+ 1UL << PG_writeback | 1UL << PG_reserved | \
+ 1UL << PG_slab | 1UL << PG_active | \
+ 1UL << PG_unevictable | __PG_MLOCKED)
/*
* Flags checked when a page is prepped for return by the page allocator.
diff --git a/include/trace/events/mmflags.h b/include/trace/events/mmflags.h
index 5a81ab4..30c2adb 100644
--- a/include/trace/events/mmflags.h
+++ b/include/trace/events/mmflags.h
@@ -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" }, \
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 19e796d..f283c7e 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -764,12 +764,11 @@
*/
#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 @@
#undef mlock
#undef writeback
#undef lru
-#undef swapbacked
#undef head
#undef slab
#undef reserved
diff --git a/mm/migrate.c b/mm/migrate.c
index 0ed24b1..87f4d0f 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -466,13 +466,15 @@
*/
newpage->index = page->index;
newpage->mapping = page->mapping;
- if (PageSwapBacked(page))
- __SetPageSwapBacked(newpage);
-
get_page(newpage); /* add cache reference */
- if (PageSwapCache(page)) {
- SetPageSwapCache(newpage);
- set_page_private(newpage, page_private(page));
+ 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 */
