2 files changed, 24 insertions, 1 deletions

diff --git a/include/linux/frontswap.h b/include/linux/frontswap.h
index 0e4e2eec5c1d..30442547b9e6 100644
--- a/include/linux/frontswap.h
+++ b/include/linux/frontswap.h
@@ -19,6 +19,8 @@ extern struct frontswap_ops
 extern void frontswap_shrink(unsigned long);
 extern unsigned long frontswap_curr_pages(void);
 extern void frontswap_writethrough(bool);
+#define FRONTSWAP_HAS_EXCLUSIVE_GETS
+extern void frontswap_tmem_exclusive_gets(bool);
 
 extern void __frontswap_init(unsigned type);
 extern int __frontswap_store(struct page *page);
diff --git a/mm/frontswap.c b/mm/frontswap.c
index 0547a35f798b..2890e67d6026 100644
--- a/mm/frontswap.c
+++ b/mm/frontswap.c
@@ -44,6 +44,13 @@ EXPORT_SYMBOL(frontswap_enabled);
  */
 static bool frontswap_writethrough_enabled __read_mostly;
 
+/*
+ * If enabled, the underlying tmem implementation is capable of doing
+ * exclusive gets, so frontswap_load, on a successful tmem_get must
+ * mark the page as no longer in frontswap AND mark it dirty.
+ */
+static bool frontswap_tmem_exclusive_gets_enabled __read_mostly;
+
 #ifdef CONFIG_DEBUG_FS
 /*
  * Counters available via /sys/kernel/debug/frontswap (if debugfs is
@@ -97,6 +104,15 @@ void frontswap_writethrough(bool enable)
 EXPORT_SYMBOL(frontswap_writethrough);
 
 /*
+ * Enable/disable frontswap exclusive gets (see above).
+ */
+void frontswap_tmem_exclusive_gets(bool enable)
+{
+        frontswap_tmem_exclusive_gets_enabled = enable;
+}
+EXPORT_SYMBOL(frontswap_tmem_exclusive_gets);
+
+/*
  * Called when a swap device is swapon'd.
  */
 void __frontswap_init(unsigned type)
@@ -174,8 +190,13 @@ int __frontswap_load(struct page *page)
         BUG_ON(sis == NULL);
         if (frontswap_test(sis, offset))
                 ret = frontswap_ops.load(type, offset, page);
-        if (ret == 0)
+        if (ret == 0) {
                 inc_frontswap_loads();
+                if (frontswap_tmem_exclusive_gets_enabled) {
+                        SetPageDirty(page);
+                        frontswap_clear(sis, offset);
+                }
+        }
         return ret;
 }
 EXPORT_SYMBOL(__frontswap_load);