diff options
Diffstat (limited to 'mm/swap_slots.c')
| -rw-r--r-- | mm/swap_slots.c | 11 |
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: |