respin of PageWaiters patch

index 74e4dda91238..a57c909a15e4 100644
@@ -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

@@ -701,12 +709,12 @@ static inline void ClearPageSlabPfmemalloc(struct page *page)
  * 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.

index 5a81ab48a2fb..30c2adbdebe8 100644
@@ -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"	},		\

index 4424784ac374..fe6b4036664a 100644
@@ -1758,6 +1758,8 @@ static inline spinlock_t *pmd_lock(struct mm_struct *mm, pmd_t *pmd)
 	return ptl;
 }
 
+extern void __init pagecache_init(void);
+
 extern void free_area_init(unsigned long * zones_size);
 extern void free_area_init_node(int nid, unsigned long * zones_size,
 		unsigned long zone_start_pfn, unsigned long *zholes_size);

index a57c909a15e4..c56b39890a41 100644
@@ -73,6 +73,7 @@
  */
 enum pageflags {
 	PG_locked,		/* Page is locked. Don't touch. */
+	PG_waiters,		/* Page has waiters, check its waitqueue */
 	PG_error,
 	PG_referenced,
 	PG_uptodate,

@@ -169,6 +170,9 @@ static __always_inline int PageCompound(struct page *page)
  *     for compound page all operations related to the page flag applied to
  *     head page.
  *
+ * PF_ONLY_HEAD:
+ *     for compound page, callers only ever operate on the head page.
+ *
  * PF_NO_TAIL:
  *     modifications of the page flag must be done on small or head pages,
  *     checks can be done on tail pages too.

@@ -178,6 +182,9 @@ static __always_inline int PageCompound(struct page *page)
  */
 #define PF_ANY(page, enforce)	page
 #define PF_HEAD(page, enforce)	compound_head(page)
+#define PF_ONLY_HEAD(page, enforce) ({					\
+		VM_BUG_ON_PGFLAGS(PageTail(page), page);		\
+		page;})
 #define PF_NO_TAIL(page, enforce) ({					\
 		VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page);	\
 		compound_head(page);})

@@ -255,6 +262,7 @@ static inline int TestClearPage##uname(struct page *page) { return 0; }
 	TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname)
 
 __PAGEFLAG(Locked, locked, PF_NO_TAIL)
+PAGEFLAG(Waiters, waiters, PF_ONLY_HEAD) __CLEARPAGEFLAG(Waiters, waiters, PF_ONLY_HEAD)
 PAGEFLAG(Error, error, PF_NO_COMPOUND) TESTCLEARFLAG(Error, error, PF_NO_COMPOUND)
 PAGEFLAG(Referenced, referenced, PF_HEAD)
 	TESTCLEARFLAG(Referenced, referenced, PF_HEAD)

@@ -743,6 +751,7 @@ static inline int page_has_private(struct page *page)
 
 #undef PF_ANY
 #undef PF_HEAD
+#undef PF_ONLY_HEAD
 #undef PF_NO_TAIL
 #undef PF_NO_COMPOUND
 #endif /* !__GENERATING_BOUNDS_H */

index 7dbe9148b2f8..d7f25f754d60 100644
@@ -486,22 +486,14 @@ static inline int lock_page_or_retry(struct page *page, struct mm_struct *mm,
  * and for filesystems which need to wait on PG_private.
  */
 extern void wait_on_page_bit(struct page *page, int bit_nr);
-
 extern int wait_on_page_bit_killable(struct page *page, int bit_nr);
-extern int wait_on_page_bit_killable_timeout(struct page *page,
-					     int bit_nr, unsigned long timeout);
-
-static inline int wait_on_page_locked_killable(struct page *page)
-{
-	if (!PageLocked(page))
-		return 0;
-	return wait_on_page_bit_killable(compound_head(page), PG_locked);
-}
+extern void wake_up_page_bit(struct page *page, int bit_nr);
 
-extern wait_queue_head_t *page_waitqueue(struct page *page);
 static inline void wake_up_page(struct page *page, int bit)
 {
-	__wake_up_bit(page_waitqueue(page), &page->flags, bit);
+	if (!PageWaiters(page))
+		return;
+	wake_up_page_bit(page, bit);
 }
 
 /* 

@@ -517,6 +509,13 @@ static inline void wait_on_page_locked(struct page *page)
 		wait_on_page_bit(compound_head(page), PG_locked);
 }
 
+static inline int wait_on_page_locked_killable(struct page *page)
+{
+	if (!PageLocked(page))
+		return 0;
+	return wait_on_page_bit_killable(compound_head(page), PG_locked);
+}
+
 /* 
  * Wait for a page to complete writeback
  */

index c78f9f0920b5..5527d910ba3d 100644
@@ -375,7 +375,6 @@ void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty);
 unsigned long wb_calc_thresh(struct bdi_writeback *wb, unsigned long thresh);
 
 void wb_update_bandwidth(struct bdi_writeback *wb, unsigned long start_time);
-void page_writeback_init(void);
 void balance_dirty_pages_ratelimited(struct address_space *mapping);
 bool wb_over_bg_thresh(struct bdi_writeback *wb);
 

index 30c2adbdebe8..9e687ca9a307 100644
@@ -81,6 +81,7 @@
 
 #define __def_pageflag_names						\
 	{1UL << PG_locked,		"locked"	},		\
+	{1UL << PG_waiters,		"waiters"	},		\
 	{1UL << PG_error,		"error"		},		\
 	{1UL << PG_referenced,		"referenced"	},		\
 	{1UL << PG_uptodate,		"uptodate"	},		\

index c81c9fa21bc7..b0c9d6facef9 100644
@@ -647,9 +647,8 @@ asmlinkage __visible void __init start_kernel(void)
 	security_init();
 	dbg_late_init();
 	vfs_caches_init();
+	pagecache_init();
 	signals_init();
-	/* rootfs populating might need page-writeback */
-	page_writeback_init();
 	proc_root_init();
 	nsfs_init();
 	cpuset_init();

219 lines not on this page · raw message

index 44d68895a9b9..7aa2ea0a8623 100644
@@ -36,6 +36,8 @@
 /* Do not use these with a slab allocator */
 #define GFP_SLAB_BUG_MASK (__GFP_DMA32|__GFP_HIGHMEM|~__GFP_BITS_MASK)
 
+void page_writeback_init(void);
+
 int do_swap_page(struct vm_fault *vmf);
 
 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *start_vma,

index 4dcf852e1e6d..844baedd2429 100644
@@ -69,6 +69,7 @@ static void __page_cache_release(struct page *page)
 		del_page_from_lru_list(page, lruvec, page_off_lru(page));
 		spin_unlock_irqrestore(zone_lru_lock(zone), flags);
 	}
+	__ClearPageWaiters(page);
 	mem_cgroup_uncharge(page);
 }
 

@@ -784,6 +785,7 @@ void release_pages(struct page **pages, int nr, bool cold)
 
 		/* Clear Active bit in case of parallel mark_page_accessed */
 		__ClearPageActive(page);
+		__ClearPageWaiters(page);
 
 		list_add(&page->lru, &pages_to_free);
 	}