1 // SPDX-License-Identifier: GPL-2.0
11  * it into local per cpu caches.  This has the advantage
31 #include <linux/cpu.h>
67 /* Must not be called with cpu hot plug lock */
73 		/* serialize with cpu hotplug operations */  in disable_swap_slots_cache_lock()
113 static int alloc_swap_slot_cache(unsigned int cpu)  in alloc_swap_slot_cache()  argument
126 		return -ENOMEM;  in alloc_swap_slot_cache()
132 		return -ENOMEM;  in alloc_swap_slot_cache()
136 	cache = &per_cpu(swp_slots, cpu);  in alloc_swap_slot_cache()
137 	if (cache->slots || cache->slots_ret) {  in alloc_swap_slot_cache()
147 	if (!cache->lock_initialized) {  in alloc_swap_slot_cache()
148 		mutex_init(&cache->alloc_lock);  in alloc_swap_slot_cache()
149 		spin_lock_init(&cache->free_lock);  in alloc_swap_slot_cache()
150 		cache->lock_initialized = true;  in alloc_swap_slot_cache()
152 	cache->nr = 0;  in alloc_swap_slot_cache()
153 	cache->cur = 0;  in alloc_swap_slot_cache()
154 	cache->n_ret = 0;  in alloc_swap_slot_cache()
157 	 * !cache->slots or !cache->slots_ret to know if it is safe to acquire  in alloc_swap_slot_cache()
162 	cache->slots = slots;  in alloc_swap_slot_cache()
163 	cache->slots_ret = slots_ret;  in alloc_swap_slot_cache()
168 static void drain_slots_cache_cpu(unsigned int cpu, unsigned int type,  in drain_slots_cache_cpu()  argument
174 	cache = &per_cpu(swp_slots, cpu);  in drain_slots_cache_cpu()
175 	if ((type & SLOTS_CACHE) && cache->slots) {  in drain_slots_cache_cpu()
176 		mutex_lock(&cache->alloc_lock);  in drain_slots_cache_cpu()
177 		swapcache_free_entries(cache->slots + cache->cur, cache->nr);  in drain_slots_cache_cpu()
178 		cache->cur = 0;  in drain_slots_cache_cpu()
179 		cache->nr = 0;  in drain_slots_cache_cpu()
180 		if (free_slots && cache->slots) {  in drain_slots_cache_cpu()
181 			kvfree(cache->slots);  in drain_slots_cache_cpu()
182 			cache->slots = NULL;  in drain_slots_cache_cpu()
184 		mutex_unlock(&cache->alloc_lock);  in drain_slots_cache_cpu()
186 	if ((type & SLOTS_CACHE_RET) && cache->slots_ret) {  in drain_slots_cache_cpu()
187 		spin_lock_irq(&cache->free_lock);  in drain_slots_cache_cpu()
188 		swapcache_free_entries(cache->slots_ret, cache->n_ret);  in drain_slots_cache_cpu()
189 		cache->n_ret = 0;  in drain_slots_cache_cpu()
190 		if (free_slots && cache->slots_ret) {  in drain_slots_cache_cpu()
191 			slots = cache->slots_ret;  in drain_slots_cache_cpu()
192 			cache->slots_ret = NULL;  in drain_slots_cache_cpu()
194 		spin_unlock_irq(&cache->free_lock);  in drain_slots_cache_cpu()
201 	unsigned int cpu;  in __drain_swap_slots_cache()  local
212 	 * We cannot acquire cpu hot plug lock here as  in __drain_swap_slots_cache()
213 	 * this function can be invoked in the cpu  in __drain_swap_slots_cache()
215 	 * cpu_up -> lock cpu_hotplug -> cpu hotplug state callback  in __drain_swap_slots_cache()
216 	 *   -> memory allocation -> direct reclaim -> folio_alloc_swap  in __drain_swap_slots_cache()
217 	 *   -> drain_swap_slots_cache  in __drain_swap_slots_cache()
219 	 * Hence the loop over current online cpu below could miss cpu that  in __drain_swap_slots_cache()
222 	 * cpu before it has been marked online. Hence, we will not  in __drain_swap_slots_cache()
223 	 * fill any swap slots in slots cache of such cpu.  in __drain_swap_slots_cache()
224 	 * There are no slots on such cpu that need to be drained.  in __drain_swap_slots_cache()
226 	for_each_online_cpu(cpu)  in __drain_swap_slots_cache()
227 		drain_slots_cache_cpu(cpu, type, false);  in __drain_swap_slots_cache()
230 static int free_slot_cache(unsigned int cpu)  in free_slot_cache()  argument
233 	drain_slots_cache_cpu(cpu, SLOTS_CACHE | SLOTS_CACHE_RET, true);  in free_slot_cache()
264 	cache->cur = 0;  in refill_swap_slots_cache()
266 		cache->nr = get_swap_pages(SWAP_SLOTS_CACHE_SIZE,  in refill_swap_slots_cache()
267 					   cache->slots, 1);  in refill_swap_slots_cache()
269 	return cache->nr;  in refill_swap_slots_cache()
277 	if (likely(use_swap_slot_cache && cache->slots_ret)) {  in free_swap_slot()
278 		spin_lock_irq(&cache->free_lock);  in free_swap_slot()
280 		if (!use_swap_slot_cache || !cache->slots_ret) {  in free_swap_slot()
281 			spin_unlock_irq(&cache->free_lock);  in free_swap_slot()
284 		if (cache->n_ret >= SWAP_SLOTS_CACHE_SIZE) {  in free_swap_slot()
291 			swapcache_free_entries(cache->slots_ret, cache->n_ret);  in free_swap_slot()
292 			cache->n_ret = 0;  in free_swap_slot()
294 		cache->slots_ret[cache->n_ret++] = entry;  in free_swap_slot()
295 		spin_unlock_irq(&cache->free_lock);  in free_swap_slot()
318 	 * accesses to the per-CPU data structure are protected by the  in folio_alloc_swap()
319 	 * mutex cache->alloc_lock.  in folio_alloc_swap()
321 	 * The alloc path here does not touch cache->slots_ret  in folio_alloc_swap()
322 	 * so cache->free_lock is not taken.  in folio_alloc_swap()
326 	if (likely(check_cache_active() && cache->slots)) {  in folio_alloc_swap()
327 		mutex_lock(&cache->alloc_lock);  in folio_alloc_swap()
328 		if (cache->slots) {  in folio_alloc_swap()
330 			if (cache->nr) {  in folio_alloc_swap()
331 				entry = cache->slots[cache->cur];  in folio_alloc_swap()
332 				cache->slots[cache->cur++].val = 0;  in folio_alloc_swap()
333 				cache->nr--;  in folio_alloc_swap()
338 		mutex_unlock(&cache->alloc_lock);  in folio_alloc_swap()