1 files changed, 0 insertions, 353 deletions
diff --git a/mm/swap_slots.c b/mm/swap_slots.c
deleted file mode 100644
index 13ab3b771409..000000000000
--- a/mm/swap_slots.c
+++ /dev/null
@@ -1,353 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Manage cache of swap slots to be used for and returned from
- * swap.
- *
- * Copyright(c) 2016 Intel Corporation.
- *
- * Author: Tim Chen <tim.c.chen@linux.intel.com>
- *
- * We allocate the swap slots from the global pool and put
- * it into local per cpu caches.  This has the advantage
- * of no needing to acquire the swap_info lock every time
- * we need a new slot.
- *
- * There is also opportunity to simply return the slot
- * to local caches without needing to acquire swap_info
- * lock.  We do not reuse the returned slots directly but
- * move them back to the global pool in a batch.  This
- * allows the slots to coalesce and reduce fragmentation.
- *
- * The swap entry allocated is marked with SWAP_HAS_CACHE
- * flag in map_count that prevents it from being allocated
- * again from the global pool.
- *
- * The swap slots cache is protected by a mutex instead of
- * a spin lock as when we search for slots with scan_swap_map,
- * we can possibly sleep.
- */
-
-#include <linux/swap_slots.h>
-#include <linux/cpu.h>
-#include <linux/cpumask.h>
-#include <linux/slab.h>
-#include <linux/vmalloc.h>
-#include <linux/mutex.h>
-#include <linux/mm.h>
-
-static DEFINE_PER_CPU(struct swap_slots_cache, swp_slots);
-static bool	swap_slot_cache_active;
-bool	swap_slot_cache_enabled;
-static bool	swap_slot_cache_initialized;
-static DEFINE_MUTEX(swap_slots_cache_mutex);
-/* Serialize swap slots cache enable/disable operations */
-static DEFINE_MUTEX(swap_slots_cache_enable_mutex);
-
-static void __drain_swap_slots_cache(unsigned int type);
-
-#define use_swap_slot_cache (swap_slot_cache_active && swap_slot_cache_enabled)
-#define SLOTS_CACHE 0x1
-#define SLOTS_CACHE_RET 0x2
-
-static void deactivate_swap_slots_cache(void)
-{
-	mutex_lock(&swap_slots_cache_mutex);
-	swap_slot_cache_active = false;
-	__drain_swap_slots_cache(SLOTS_CACHE|SLOTS_CACHE_RET);
-	mutex_unlock(&swap_slots_cache_mutex);
-}
-
-static void reactivate_swap_slots_cache(void)
-{
-	mutex_lock(&swap_slots_cache_mutex);
-	swap_slot_cache_active = true;
-	mutex_unlock(&swap_slots_cache_mutex);
-}
-
-/* Must not be called with cpu hot plug lock */
-void disable_swap_slots_cache_lock(void)
-{
-	mutex_lock(&swap_slots_cache_enable_mutex);
-	swap_slot_cache_enabled = false;
-	if (swap_slot_cache_initialized) {
-		/* serialize with cpu hotplug operations */
-		cpus_read_lock();
-		__drain_swap_slots_cache(SLOTS_CACHE|SLOTS_CACHE_RET);
-		cpus_read_unlock();
-	}
-}
-
-static void __reenable_swap_slots_cache(void)
-{
-	swap_slot_cache_enabled = has_usable_swap();
-}
-
-void reenable_swap_slots_cache_unlock(void)
-{
-	__reenable_swap_slots_cache();
-	mutex_unlock(&swap_slots_cache_enable_mutex);
-}
-
-static bool check_cache_active(void)
-{
-	long pages;
-
-	if (!swap_slot_cache_enabled)
-		return false;
-
-	pages = get_nr_swap_pages();
-	if (!swap_slot_cache_active) {
-		if (pages > num_online_cpus() *
-		    THRESHOLD_ACTIVATE_SWAP_SLOTS_CACHE)
-			reactivate_swap_slots_cache();
-		goto out;
-	}
-
-	/* if global pool of slot caches too low, deactivate cache */
-	if (pages < num_online_cpus() * THRESHOLD_DEACTIVATE_SWAP_SLOTS_CACHE)
-		deactivate_swap_slots_cache();
-out:
-	return swap_slot_cache_active;
-}
-
-static int alloc_swap_slot_cache(unsigned int cpu)
-{
-	struct swap_slots_cache *cache;
-	swp_entry_t *slots, *slots_ret;
-
-	/*
-	 * Do allocation outside swap_slots_cache_mutex
-	 * as kvzalloc could trigger reclaim and folio_alloc_swap,
-	 * which can lock swap_slots_cache_mutex.
-	 */
-	slots = kvcalloc(SWAP_SLOTS_CACHE_SIZE, sizeof(swp_entry_t),
-			 GFP_KERNEL);
-	if (!slots)
-		return -ENOMEM;
-
-	slots_ret = kvcalloc(SWAP_SLOTS_CACHE_SIZE, sizeof(swp_entry_t),
-			     GFP_KERNEL);
-	if (!slots_ret) {
-		kvfree(slots);
-		return -ENOMEM;
-	}
-
-	mutex_lock(&swap_slots_cache_mutex);
-	cache = &per_cpu(swp_slots, cpu);
-	if (cache->slots || cache->slots_ret) {
-		/* cache already allocated */
-		mutex_unlock(&swap_slots_cache_mutex);
-
-		kvfree(slots);
-		kvfree(slots_ret);
-
-		return 0;
-	}
-
-	if (!cache->lock_initialized) {
-		mutex_init(&cache->alloc_lock);
-		spin_lock_init(&cache->free_lock);
-		cache->lock_initialized = true;
-	}
-	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;
-	cache->slots_ret = slots_ret;
-	mutex_unlock(&swap_slots_cache_mutex);
-	return 0;
-}
-
-static void drain_slots_cache_cpu(unsigned int cpu, unsigned int type,
-				  bool free_slots)
-{
-	struct swap_slots_cache *cache;
-	swp_entry_t *slots = NULL;
-
-	cache = &per_cpu(swp_slots, cpu);
-	if ((type & SLOTS_CACHE) && cache->slots) {
-		mutex_lock(&cache->alloc_lock);
-		swapcache_free_entries(cache->slots + cache->cur, cache->nr);
-		cache->cur = 0;
-		cache->nr = 0;
-		if (free_slots && cache->slots) {
-			kvfree(cache->slots);
-			cache->slots = NULL;
-		}
-		mutex_unlock(&cache->alloc_lock);
-	}
-	if ((type & SLOTS_CACHE_RET) && cache->slots_ret) {
-		spin_lock_irq(&cache->free_lock);
-		swapcache_free_entries(cache->slots_ret, cache->n_ret);
-		cache->n_ret = 0;
-		if (free_slots && cache->slots_ret) {
-			slots = cache->slots_ret;
-			cache->slots_ret = NULL;
-		}
-		spin_unlock_irq(&cache->free_lock);
-		kvfree(slots);
-	}
-}
-
-static void __drain_swap_slots_cache(unsigned int type)
-{
-	unsigned int cpu;
-
-	/*
-	 * This function is called during
-	 *	1) swapoff, when we have to make sure no
-	 *	   left over slots are in cache when we remove
-	 *	   a swap device;
-	 *      2) disabling of swap slot cache, when we run low
-	 *	   on swap slots when allocating memory and need
-	 *	   to return swap slots to global pool.
-	 *
-	 * We cannot acquire cpu hot plug lock here as
-	 * this function can be invoked in the cpu
-	 * hot plug path:
-	 * cpu_up -> lock cpu_hotplug -> cpu hotplug state callback
-	 *   -> memory allocation -> direct reclaim -> folio_alloc_swap
-	 *   -> drain_swap_slots_cache
-	 *
-	 * Hence the loop over current online cpu below could miss cpu that
-	 * is being brought online but not yet marked as online.
-	 * That is okay as we do not schedule and run anything on a
-	 * cpu before it has been marked online. Hence, we will not
-	 * fill any swap slots in slots cache of such cpu.
-	 * There are no slots on such cpu that need to be drained.
-	 */
-	for_each_online_cpu(cpu)
-		drain_slots_cache_cpu(cpu, type, false);
-}
-
-static int free_slot_cache(unsigned int cpu)
-{
-	mutex_lock(&swap_slots_cache_mutex);
-	drain_slots_cache_cpu(cpu, SLOTS_CACHE | SLOTS_CACHE_RET, true);
-	mutex_unlock(&swap_slots_cache_mutex);
-	return 0;
-}
-
-void enable_swap_slots_cache(void)
-{
-	mutex_lock(&swap_slots_cache_enable_mutex);
-	if (!swap_slot_cache_initialized) {
-		int ret;
-
-		ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "swap_slots_cache",
-					alloc_swap_slot_cache, free_slot_cache);
-		if (WARN_ONCE(ret < 0, "Cache allocation failed (%s), operating "
-				       "without swap slots cache.\n", __func__))
-			goto out_unlock;
-
-		swap_slot_cache_initialized = true;
-	}
-
-	__reenable_swap_slots_cache();
-out_unlock:
-	mutex_unlock(&swap_slots_cache_enable_mutex);
-}
-
-/* called with swap slot cache's alloc lock held */
-static int refill_swap_slots_cache(struct swap_slots_cache *cache)
-{
-	if (!use_swap_slot_cache)
-		return 0;
-
-	cache->cur = 0;
-	if (swap_slot_cache_active)
-		cache->nr = get_swap_pages(SWAP_SLOTS_CACHE_SIZE,
-					   cache->slots, 0);
-
-	return cache->nr;
-}
-
-void free_swap_slot(swp_entry_t entry)
-{
-	struct swap_slots_cache *cache;
-
-	/* Large folio swap slot is not covered. */
-	zswap_invalidate(entry);
-
-	cache = raw_cpu_ptr(&swp_slots);
-	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) {
-			spin_unlock_irq(&cache->free_lock);
-			goto direct_free;
-		}
-		if (cache->n_ret >= SWAP_SLOTS_CACHE_SIZE) {
-			/*
-			 * Return slots to global pool.
-			 * The current swap_map value is SWAP_HAS_CACHE.
-			 * Set it to 0 to indicate it is available for
-			 * allocation in global pool
-			 */
-			swapcache_free_entries(cache->slots_ret, cache->n_ret);
-			cache->n_ret = 0;
-		}
-		cache->slots_ret[cache->n_ret++] = entry;
-		spin_unlock_irq(&cache->free_lock);
-	} else {
-direct_free:
-		swapcache_free_entries(&entry, 1);
-	}
-}
-
-swp_entry_t folio_alloc_swap(struct folio *folio)
-{
-	swp_entry_t entry;
-	struct swap_slots_cache *cache;
-
-	entry.val = 0;
-
-	if (folio_test_large(folio)) {
-		if (IS_ENABLED(CONFIG_THP_SWAP))
-			get_swap_pages(1, &entry, folio_order(folio));
-		goto out;
-	}
-
-	/*
-	 * Preemption is allowed here, because we may sleep
-	 * in refill_swap_slots_cache().  But it is safe, because
-	 * accesses to the per-CPU data structure are protected by the
-	 * mutex cache->alloc_lock.
-	 *
-	 * The alloc path here does not touch cache->slots_ret
-	 * so cache->free_lock is not taken.
-	 */
-	cache = raw_cpu_ptr(&swp_slots);
-
-	if (likely(check_cache_active() && cache->slots)) {
-		mutex_lock(&cache->alloc_lock);
-		if (cache->slots) {
-repeat:
-			if (cache->nr) {
-				entry = cache->slots[cache->cur];
-				cache->slots[cache->cur++].val = 0;
-				cache->nr--;
-			} else if (refill_swap_slots_cache(cache)) {
-				goto repeat;
-			}
-		}
-		mutex_unlock(&cache->alloc_lock);
-		if (entry.val)
-			goto out;
-	}
-
-	get_swap_pages(1, &entry, 0);
-out:
-	if (mem_cgroup_try_charge_swap(folio, entry)) {
-		put_swap_folio(folio, entry);
-		entry.val = 0;
-	}
-	return entry;
-}