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-rw-r--r--include/linux/swap_slots.h2
-rw-r--r--mm/swap_slots.c2
-rw-r--r--mm/swap_state.c13
3 files changed, 13 insertions, 4 deletions
diff --git a/include/linux/swap_slots.h b/include/linux/swap_slots.h
index ba5623b..6ef92d1 100644
--- a/include/linux/swap_slots.h
+++ b/include/linux/swap_slots.h
@@ -25,4 +25,6 @@ void reenable_swap_slots_cache_unlock(void);
int enable_swap_slots_cache(void);
int free_swap_slot(swp_entry_t entry);
+extern bool swap_slot_cache_enabled;
+
#endif /* _LINUX_SWAP_SLOTS_H */
diff --git a/mm/swap_slots.c b/mm/swap_slots.c
index ebf4f1c..9b5bc86 100644
--- a/mm/swap_slots.c
+++ b/mm/swap_slots.c
@@ -36,7 +36,7 @@
static DEFINE_PER_CPU(struct swap_slots_cache, swp_slots);
static bool swap_slot_cache_active;
-static bool swap_slot_cache_enabled;
+bool swap_slot_cache_enabled;
static bool swap_slot_cache_initialized;
DEFINE_MUTEX(swap_slots_cache_mutex);
/* Serialize swap slots cache enable/disable operations */
diff --git a/mm/swap_state.c b/mm/swap_state.c
index e1f07ca..473b71e 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -324,9 +324,16 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
if (found_page)
break;
- /* Just skip read ahead for unused swap slot */
- if (!__swp_swapcount(entry))
- return NULL;
+ /*
+ * Just skip read ahead for unused swap slot.
+ * During swap_off when swap_slot_cache is disabled,
+ * we have to handle the race between putting
+ * swap entry in swap cache and marking swap slot
+ * as SWAP_HAS_CACHE. That's done in later part of code or
+ * else swap_off will be aborted if we return NULL.
+ */
+ if (!__swp_swapcount(entry) && swap_slot_cache_enabled)
+ break;
/*
* Get a new page to read into from swap.
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