/* protected with swap_lock. reading in vm_swap_full() doesn't need lock */
long total_swap_pages;
static int least_priority;
-static atomic_t highest_priority_index = ATOMIC_INIT(-1);
static const char Bad_file[] = "Bad swap file entry ";
static const char Unused_file[] = "Unused swap file entry ";
static const char Bad_offset[] = "Bad swap offset entry ";
static const char Unused_offset[] = "Unused swap offset entry ";
-struct swap_list_t swap_list = {-1, -1};
+/*
+ * all active swap_info_structs
+ * protected with swap_lock, and ordered by priority.
+ */
+PLIST_HEAD(swap_active_head);
+
+/*
+ * all available (active, not full) swap_info_structs
+ * protected with swap_avail_lock, ordered by priority.
+ * This is used by get_swap_page() instead of swap_active_head
+ * because swap_active_head includes all swap_info_structs,
+ * but get_swap_page() doesn't need to look at full ones.
+ * This uses its own lock instead of swap_lock because when a
+ * swap_info_struct changes between not-full/full, it needs to
+ * add/remove itself to/from this list, but the swap_info_struct->lock
+ * is held and the locking order requires swap_lock to be taken
+ * before any swap_info_struct->lock.
+ */
+static PLIST_HEAD(swap_avail_head);
+static DEFINE_SPINLOCK(swap_avail_lock);
struct swap_info_struct *swap_info[MAX_SWAPFILES];
if (si->inuse_pages == si->pages) {
si->lowest_bit = si->max;
si->highest_bit = 0;
+ spin_lock(&swap_avail_lock);
+ plist_del(&si->avail_list, &swap_avail_head);
+ spin_unlock(&swap_avail_lock);
}
si->swap_map[offset] = usage;
inc_cluster_info_page(si, si->cluster_info, offset);
swp_entry_t get_swap_page(void)
{
- struct swap_info_struct *si;
+ struct swap_info_struct *si, *next;
pgoff_t offset;
- int type, next;
- int wrapped = 0;
- int hp_index;
- spin_lock(&swap_lock);
if (atomic_long_read(&nr_swap_pages) <= 0)
goto noswap;
atomic_long_dec(&nr_swap_pages);
- for (type = swap_list.next; type >= 0 && wrapped < 2; type = next) {
- hp_index = atomic_xchg(&highest_priority_index, -1);
- /*
- * highest_priority_index records current highest priority swap
- * type which just frees swap entries. If its priority is
- * higher than that of swap_list.next swap type, we use it. It
- * isn't protected by swap_lock, so it can be an invalid value
- * if the corresponding swap type is swapoff. We double check
- * the flags here. It's even possible the swap type is swapoff
- * and swapon again and its priority is changed. In such rare
- * case, low prority swap type might be used, but eventually
- * high priority swap will be used after several rounds of
- * swap.
- */
- if (hp_index != -1 && hp_index != type &&
- swap_info[type]->prio < swap_info[hp_index]->prio &&
- (swap_info[hp_index]->flags & SWP_WRITEOK)) {
- type = hp_index;
- swap_list.next = type;
- }
-
- si = swap_info[type];
- next = si->next;
- if (next < 0 ||
- (!wrapped && si->prio != swap_info[next]->prio)) {
- next = swap_list.head;
- wrapped++;
- }
+ spin_lock(&swap_avail_lock);
+start_over:
+ plist_for_each_entry_safe(si, next, &swap_avail_head, avail_list) {
+ /* requeue si to after same-priority siblings */
+ plist_requeue(&si->avail_list, &swap_avail_head);
+ spin_unlock(&swap_avail_lock);
spin_lock(&si->lock);
- if (!si->highest_bit) {
- spin_unlock(&si->lock);
- continue;
- }
- if (!(si->flags & SWP_WRITEOK)) {
+ if (!si->highest_bit || !(si->flags & SWP_WRITEOK)) {
+ spin_lock(&swap_avail_lock);
+ if (plist_node_empty(&si->avail_list)) {
+ spin_unlock(&si->lock);
+ goto nextsi;
+ }
+ WARN(!si->highest_bit,
+ "swap_info %d in list but !highest_bit\n",
+ si->type);
+ WARN(!(si->flags & SWP_WRITEOK),
+ "swap_info %d in list but !SWP_WRITEOK\n",
+ si->type);
+ plist_del(&si->avail_list, &swap_avail_head);
spin_unlock(&si->lock);
- continue;
+ goto nextsi;
}
- swap_list.next = next;
-
- spin_unlock(&swap_lock);
/* This is called for allocating swap entry for cache */
offset = scan_swap_map(si, SWAP_HAS_CACHE);
spin_unlock(&si->lock);
if (offset)
- return swp_entry(type, offset);
- spin_lock(&swap_lock);
- next = swap_list.next;
+ return swp_entry(si->type, offset);
+ pr_debug("scan_swap_map of si %d failed to find offset\n",
+ si->type);
+ spin_lock(&swap_avail_lock);
+nextsi:
+ /*
+ * if we got here, it's likely that si was almost full before,
+ * and since scan_swap_map() can drop the si->lock, multiple
+ * callers probably all tried to get a page from the same si
+ * and it filled up before we could get one; or, the si filled
+ * up between us dropping swap_avail_lock and taking si->lock.
+ * Since we dropped the swap_avail_lock, the swap_avail_head
+ * list may have been modified; so if next is still in the
+ * swap_avail_head list then try it, otherwise start over.
+ */
+ if (plist_node_empty(&next->avail_list))
+ goto start_over;
}
+ spin_unlock(&swap_avail_lock);
+
atomic_long_inc(&nr_swap_pages);
noswap:
- spin_unlock(&swap_lock);
return (swp_entry_t) {0};
}
return NULL;
}
-/*
- * This swap type frees swap entry, check if it is the highest priority swap
- * type which just frees swap entry. get_swap_page() uses
- * highest_priority_index to search highest priority swap type. The
- * swap_info_struct.lock can't protect us if there are multiple swap types
- * active, so we use atomic_cmpxchg.
- */
-static void set_highest_priority_index(int type)
-{
- int old_hp_index, new_hp_index;
-
- do {
- old_hp_index = atomic_read(&highest_priority_index);
- if (old_hp_index != -1 &&
- swap_info[old_hp_index]->prio >= swap_info[type]->prio)
- break;
- new_hp_index = type;
- } while (atomic_cmpxchg(&highest_priority_index,
- old_hp_index, new_hp_index) != old_hp_index);
-}
-
static unsigned char swap_entry_free(struct swap_info_struct *p,
swp_entry_t entry, unsigned char usage)
{
dec_cluster_info_page(p, p->cluster_info, offset);
if (offset < p->lowest_bit)
p->lowest_bit = offset;
- if (offset > p->highest_bit)
+ if (offset > p->highest_bit) {
+ bool was_full = !p->highest_bit;
p->highest_bit = offset;
- set_highest_priority_index(p->type);
+ if (was_full && (p->flags & SWP_WRITEOK)) {
+ spin_lock(&swap_avail_lock);
+ WARN_ON(!plist_node_empty(&p->avail_list));
+ if (plist_node_empty(&p->avail_list))
+ plist_add(&p->avail_list,
+ &swap_avail_head);
+ spin_unlock(&swap_avail_lock);
+ }
+ }
atomic_long_inc(&nr_swap_pages);
p->inuse_pages--;
frontswap_invalidate_page(p->type, offset);
unsigned char *swap_map,
struct swap_cluster_info *cluster_info)
{
- int i, prev;
-
if (prio >= 0)
p->prio = prio;
else
p->prio = --least_priority;
+ /*
+ * the plist prio is negated because plist ordering is
+ * low-to-high, while swap ordering is high-to-low
+ */
+ p->list.prio = -p->prio;
+ p->avail_list.prio = -p->prio;
p->swap_map = swap_map;
p->cluster_info = cluster_info;
p->flags |= SWP_WRITEOK;
atomic_long_add(p->pages, &nr_swap_pages);
total_swap_pages += p->pages;
- /* insert swap space into swap_list: */
- prev = -1;
- for (i = swap_list.head; i >= 0; i = swap_info[i]->next) {
- if (p->prio >= swap_info[i]->prio)
- break;
- prev = i;
- }
- p->next = i;
- if (prev < 0)
- swap_list.head = swap_list.next = p->type;
- else
- swap_info[prev]->next = p->type;
+ assert_spin_locked(&swap_lock);
+ /*
+ * both lists are plists, and thus priority ordered.
+ * swap_active_head needs to be priority ordered for swapoff(),
+ * which on removal of any swap_info_struct with an auto-assigned
+ * (i.e. negative) priority increments the auto-assigned priority
+ * of any lower-priority swap_info_structs.
+ * swap_avail_head needs to be priority ordered for get_swap_page(),
+ * which allocates swap pages from the highest available priority
+ * swap_info_struct.
+ */
+ plist_add(&p->list, &swap_active_head);
+ spin_lock(&swap_avail_lock);
+ plist_add(&p->avail_list, &swap_avail_head);
+ spin_unlock(&swap_avail_lock);
}
static void enable_swap_info(struct swap_info_struct *p, int prio,
struct address_space *mapping;
struct inode *inode;
struct filename *pathname;
- int i, type, prev;
- int err;
+ int err, found = 0;
unsigned int old_block_size;
if (!capable(CAP_SYS_ADMIN))
goto out;
mapping = victim->f_mapping;
- prev = -1;
spin_lock(&swap_lock);
- for (type = swap_list.head; type >= 0; type = swap_info[type]->next) {
- p = swap_info[type];
+ plist_for_each_entry(p, &swap_active_head, list) {
if (p->flags & SWP_WRITEOK) {
- if (p->swap_file->f_mapping == mapping)
+ if (p->swap_file->f_mapping == mapping) {
+ found = 1;
break;
+ }
}
- prev = type;
}
- if (type < 0) {
+ if (!found) {
err = -EINVAL;
spin_unlock(&swap_lock);
goto out_dput;
spin_unlock(&swap_lock);
goto out_dput;
}
- if (prev < 0)
- swap_list.head = p->next;
- else
- swap_info[prev]->next = p->next;
- if (type == swap_list.next) {
- /* just pick something that's safe... */
- swap_list.next = swap_list.head;
- }
+ spin_lock(&swap_avail_lock);
+ plist_del(&p->avail_list, &swap_avail_head);
+ spin_unlock(&swap_avail_lock);
spin_lock(&p->lock);
if (p->prio < 0) {
- for (i = p->next; i >= 0; i = swap_info[i]->next)
- swap_info[i]->prio = p->prio--;
+ struct swap_info_struct *si = p;
+
+ plist_for_each_entry_continue(si, &swap_active_head, list) {
+ si->prio++;
+ si->list.prio--;
+ si->avail_list.prio--;
+ }
least_priority++;
}
+ plist_del(&p->list, &swap_active_head);
atomic_long_sub(p->pages, &nr_swap_pages);
total_swap_pages -= p->pages;
p->flags &= ~SWP_WRITEOK;
spin_unlock(&swap_lock);
set_current_oom_origin();
- err = try_to_unuse(type, false, 0); /* force all pages to be unused */
+ err = try_to_unuse(p->type, false, 0); /* force unuse all pages */
clear_current_oom_origin();
if (err) {
p->swap_map = NULL;
cluster_info = p->cluster_info;
p->cluster_info = NULL;
- p->flags = 0;
frontswap_map = frontswap_map_get(p);
spin_unlock(&p->lock);
spin_unlock(&swap_lock);
- frontswap_invalidate_area(type);
+ frontswap_invalidate_area(p->type);
frontswap_map_set(p, NULL);
mutex_unlock(&swapon_mutex);
free_percpu(p->percpu_cluster);
vfree(cluster_info);
vfree(frontswap_map);
/* Destroy swap account information */
- swap_cgroup_swapoff(type);
+ swap_cgroup_swapoff(p->type);
inode = mapping->host;
if (S_ISBLK(inode->i_mode)) {
mutex_unlock(&inode->i_mutex);
}
filp_close(swap_file, NULL);
+
+ /*
+ * Clear the SWP_USED flag after all resources are freed so that swapon
+ * can reuse this swap_info in alloc_swap_info() safely. It is ok to
+ * not hold p->lock after we cleared its SWP_WRITEOK.
+ */
+ spin_lock(&swap_lock);
+ p->flags = 0;
+ spin_unlock(&swap_lock);
+
err = 0;
atomic_inc(&proc_poll_event);
wake_up_interruptible(&proc_poll_wait);
*/
}
INIT_LIST_HEAD(&p->first_swap_extent.list);
+ plist_node_init(&p->list, 0);
+ plist_node_init(&p->avail_list, 0);
p->flags = SWP_USED;
- p->next = -1;
spin_unlock(&swap_lock);
spin_lock_init(&p->lock);
projects / platform / adaptation / renesas_rcar / renesas_kernel.git / blobdiff