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Diffstat (limited to 'mm/swap_slots.c')
-rw-r--r--mm/swap_slots.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/mm/swap_slots.c b/mm/swap_slots.c
index d81cfc5a43d5..bebc19292018 100644
--- a/mm/swap_slots.c
+++ b/mm/swap_slots.c
@@ -149,6 +149,13 @@ static int alloc_swap_slot_cache(unsigned int cpu)
cache->nr = 0;
cache->cur = 0;
cache->n_ret = 0;
+ /*
+ * We initialized alloc_lock and free_lock earlier. We use
+ * !cache->slots or !cache->slots_ret to know if it is safe to acquire
+ * the corresponding lock and use the cache. Memory barrier below
+ * ensures the assumption.
+ */
+ mb();
cache->slots = slots;
slots = NULL;
cache->slots_ret = slots_ret;
@@ -275,7 +282,7 @@ int free_swap_slot(swp_entry_t entry)
struct swap_slots_cache *cache;
cache = raw_cpu_ptr(&swp_slots);
- if (use_swap_slot_cache && cache->slots_ret) {
+ if (likely(use_swap_slot_cache && cache->slots_ret)) {
spin_lock_irq(&cache->free_lock);
/* Swap slots cache may be deactivated before acquiring lock */
if (!use_swap_slot_cache || !cache->slots_ret) {
@@ -326,7 +333,7 @@ swp_entry_t get_swap_page(struct page *page)
*/
cache = raw_cpu_ptr(&swp_slots);
- if (check_cache_active()) {
+ if (likely(check_cache_active() && cache->slots)) {
mutex_lock(&cache->alloc_lock);
if (cache->slots) {
repeat: