1 files changed, 25 insertions, 12 deletions

diff --git a/mm/filemap.c b/mm/filemap.c
index 903bf31..ab85536 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -33,6 +33,7 @@
 #include <linux/cpuset.h>
 #include <linux/hardirq.h> /* for BUG_ON(!in_atomic()) only */
 #include <linux/memcontrol.h>
+#include <linux/mm_inline.h> /* for page_is_file_cache() */
 #include "internal.h"
 
 /*
@@ -115,12 +116,12 @@ void __remove_from_page_cache(struct page *page)
 {
 	struct address_space *mapping = page->mapping;
 
-	mem_cgroup_uncharge_cache_page(page);
 	radix_tree_delete(&mapping->page_tree, page->index);
 	page->mapping = NULL;
 	mapping->nrpages--;
 	__dec_zone_page_state(page, NR_FILE_PAGES);
 	BUG_ON(page_mapped(page));
+	mem_cgroup_uncharge_cache_page(page);
 
 	/*
 	 * Some filesystems seem to re-dirty the page even after
@@ -492,9 +493,24 @@ EXPORT_SYMBOL(add_to_page_cache_locked);
 int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
 				pgoff_t offset, gfp_t gfp_mask)
 {
-	int ret = add_to_page_cache(page, mapping, offset, gfp_mask);
-	if (ret == 0)
-		lru_cache_add(page);
+	int ret;
+
+	/*
+	 * Splice_read and readahead add shmem/tmpfs pages into the page cache
+	 * before shmem_readpage has a chance to mark them as SwapBacked: they
+	 * need to go on the active_anon lru below, and mem_cgroup_cache_charge
+	 * (called in add_to_page_cache) needs to know where they're going too.
+	 */
+	if (mapping_cap_swap_backed(mapping))
+		SetPageSwapBacked(page);
+
+	ret = add_to_page_cache(page, mapping, offset, gfp_mask);
+	if (ret == 0) {
+		if (page_is_file_cache(page))
+			lru_cache_add_file(page);
+		else
+			lru_cache_add_active_anon(page);
+	}
 	return ret;
 }
 
@@ -557,17 +573,14 @@ EXPORT_SYMBOL(wait_on_page_bit);
  * mechananism between PageLocked pages and PageWriteback pages is shared.
  * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
  *
- * The first mb is necessary to safely close the critical section opened by the
- * test_and_set_bit() to lock the page; the second mb is necessary to enforce
- * ordering between the clear_bit and the read of the waitqueue (to avoid SMP
- * races with a parallel wait_on_page_locked()).
+ * The mb is necessary to enforce ordering between the clear_bit and the read
+ * of the waitqueue (to avoid SMP races with a parallel wait_on_page_locked()).
  */
 void unlock_page(struct page *page)
 {
-	smp_mb__before_clear_bit();
-	if (!test_and_clear_bit(PG_locked, &page->flags))
-		BUG();
-	smp_mb__after_clear_bit(); 
+	VM_BUG_ON(!PageLocked(page));
+	clear_bit_unlock(PG_locked, &page->flags);
+	smp_mb__after_clear_bit();
 	wake_up_page(page, PG_locked);
 }
 EXPORT_SYMBOL(unlock_page);