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mm, swap: remove swap slot cache

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Slot cache is no longer needed now, removing it and all related code.

- vm-scalability with: `usemem --init-time -O -y -x -R -31 1G`,
12G memory cgroup using simulated pmem as SWAP (32G pmem, 32 CPUs),
16 test runs for each case, measuring the total throughput:

                      Before (KB/s) (stdev)  After (KB/s) (stdev)
Random (4K):          424907.60 (24410.78)   414745.92  (34554.78)
Random (64K):         163308.82 (11635.72)   167314.50  (18434.99)
Sequential (4K, !-R): 6150056.79 (103205.90) 6321469.06 (115878.16)

The performance changes are below noise level.

- Build linux kernel with make -j96, using 4K folio with 1.5G memory
cgroup limit and 64K folio with 2G memory cgroup limit, on top of tmpfs,
12 test runs, measuring the system time:

                  Before (s) (stdev)  After (s) (stdev)
make -j96 (4K):   6445.69 (61.95)     6408.80 (69.46)
make -j96 (64K):  6841.71 (409.04)    6437.99 (435.55)

Similar to above, 64k mTHP case showed a slight improvement.

Link: https://lkml.kernel.org/r/20250313165935.63303-7-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Matthew Wilcow (Oracle) <willy@infradead.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Kairui Song 2025-03-14 00:59:34 +08:00 committed by Andrew Morton
parent 1b7e90020e
commit 0ff67f990b
6 changed files with 67 additions and 463 deletions
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3
include/linux/swap.h
View File

@ -465,7 +465,6 @@ void free_pages_and_swap_cache(struct encoded_page **, int);
extern atomic_long_t nr_swap_pages;
extern long total_swap_pages;
extern atomic_t nr_rotate_swap;
extern bool has_usable_swap(void);
/* Swap 50% full? Release swapcache more aggressively.. */
static inline bool vm_swap_full(void)
@ -483,13 +482,11 @@ swp_entry_t folio_alloc_swap(struct folio *folio);
bool folio_free_swap(struct folio *folio);
void put_swap_folio(struct folio *folio, swp_entry_t entry);
extern swp_entry_t get_swap_page_of_type(int);
extern int get_swap_pages(int n, swp_entry_t swp_entries[], int order);
extern int add_swap_count_continuation(swp_entry_t, gfp_t);
extern void swap_shmem_alloc(swp_entry_t, int);
extern int swap_duplicate(swp_entry_t);
extern int swapcache_prepare(swp_entry_t entry, int nr);
extern void swap_free_nr(swp_entry_t entry, int nr_pages);
extern void swapcache_free_entries(swp_entry_t *entries, int n);
extern void free_swap_and_cache_nr(swp_entry_t entry, int nr);
int swap_type_of(dev_t device, sector_t offset);
int find_first_swap(dev_t *device);

28
include/linux/swap_slots.h
View File

@ -1,28 +0,0 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_SWAP_SLOTS_H
#define _LINUX_SWAP_SLOTS_H
#include <linux/swap.h>
#include <linux/spinlock.h>
#include <linux/mutex.h>
#define SWAP_SLOTS_CACHE_SIZE SWAP_BATCH
#define THRESHOLD_ACTIVATE_SWAP_SLOTS_CACHE (5*SWAP_SLOTS_CACHE_SIZE)
#define THRESHOLD_DEACTIVATE_SWAP_SLOTS_CACHE (2*SWAP_SLOTS_CACHE_SIZE)
struct swap_slots_cache {
bool lock_initialized;
struct mutex alloc_lock; /* protects slots, nr, cur */
swp_entry_t *slots;
int nr;
int cur;
int n_ret;
};
void disable_swap_slots_cache_lock(void);
void reenable_swap_slots_cache_unlock(void);
void enable_swap_slots_cache(void);
extern bool swap_slot_cache_enabled;
#endif /* _LINUX_SWAP_SLOTS_H */

2
mm/Makefile
View File

@ -75,7 +75,7 @@ ifdef CONFIG_MMU
obj-$(CONFIG_ADVISE_SYSCALLS) += madvise.o
endif
obj-$(CONFIG_SWAP) += page_io.o swap_state.o swapfile.o swap_slots.o
obj-$(CONFIG_SWAP) += page_io.o swap_state.o swapfile.o
obj-$(CONFIG_ZSWAP) += zswap.o
obj-$(CONFIG_HAS_DMA) += dmapool.o
obj-$(CONFIG_HUGETLBFS) += hugetlb.o

295
mm/swap_slots.c
View File

@ -1,295 +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(void);
#define use_swap_slot_cache (swap_slot_cache_active && swap_slot_cache_enabled)
static void deactivate_swap_slots_cache(void)
{
mutex_lock(&swap_slots_cache_mutex);
swap_slot_cache_active = false;
__drain_swap_slots_cache();
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();
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;
/*
* 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;
mutex_lock(&swap_slots_cache_mutex);
cache = &per_cpu(swp_slots, cpu);
if (cache->slots) {
/* cache already allocated */
mutex_unlock(&swap_slots_cache_mutex);
kvfree(slots);
return 0;
}
if (!cache->lock_initialized) {
mutex_init(&cache->alloc_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;
mutex_unlock(&swap_slots_cache_mutex);
return 0;
}
static void drain_slots_cache_cpu(unsigned int cpu, bool free_slots)
{
struct swap_slots_cache *cache;
cache = &per_cpu(swp_slots, cpu);
if (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);
}
}
static void __drain_swap_slots_cache(void)
{
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, false);
}
static int free_slot_cache(unsigned int cpu)
{
mutex_lock(&swap_slots_cache_mutex);
drain_slots_cache_cpu(cpu, 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;
}
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;
}

8
mm/swap_state.c
View File

@ -20,7 +20,6 @@
#include <linux/blkdev.h>
#include <linux/migrate.h>
#include <linux/vmalloc.h>
#include <linux/swap_slots.h>
#include <linux/huge_mm.h>
#include <linux/shmem_fs.h>
#include "internal.h"
@ -447,13 +446,8 @@ struct folio *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
/*
* Just skip read ahead for unused swap slot.
* During swap_off when swap_slot_cache is disabled,
* we have to handle the race between putting
* swap entry in swap cache and marking swap slot
* as SWAP_HAS_CACHE. That's done in later part of code or
* else swap_off will be aborted if we return NULL.
*/
if (!swap_entry_swapped(si, entry) && swap_slot_cache_enabled)
if (!swap_entry_swapped(si, entry))
goto put_and_return;
/*

194
mm/swapfile.c
View File

@ -37,7 +37,6 @@
#include <linux/oom.h>
#include <linux/swapfile.h>
#include <linux/export.h>
#include <linux/swap_slots.h>
#include <linux/sort.h>
#include <linux/completion.h>
#include <linux/suspend.h>
@ -885,16 +884,20 @@ static unsigned long cluster_alloc_swap_entry(struct swap_info_struct *si, int o
struct swap_cluster_info *ci;
unsigned int offset = SWAP_ENTRY_INVALID, found = SWAP_ENTRY_INVALID;
if (si->flags & SWP_SOLIDSTATE) {
if (si == this_cpu_read(percpu_swap_cluster.si[order]))
offset = this_cpu_read(percpu_swap_cluster.offset[order]);
} else {
/*
* Swapfile is not block device so unable
* to allocate large entries.
*/
if (order && !(si->flags & SWP_BLKDEV))
return 0;
if (!(si->flags & SWP_SOLIDSTATE)) {
/* Serialize HDD SWAP allocation for each device. */
spin_lock(&si->global_cluster_lock);
offset = si->global_cluster->next[order];
}
if (offset == SWAP_ENTRY_INVALID)
goto new_cluster;
if (offset) {
ci = lock_cluster(si, offset);
/* Cluster could have been used by another order */
if (cluster_is_usable(ci, order)) {
@ -1153,43 +1156,6 @@ static void swap_range_free(struct swap_info_struct *si, unsigned long offset,
swap_usage_sub(si, nr_entries);
}
static int scan_swap_map_slots(struct swap_info_struct *si,
unsigned char usage, int nr,
swp_entry_t slots[], int order)
{
unsigned int nr_pages = 1 << order;
int n_ret = 0;
if (order > 0) {
/*
* Should not even be attempting large allocations when huge
* page swap is disabled. Warn and fail the allocation.
*/
if (!IS_ENABLED(CONFIG_THP_SWAP) ||
nr_pages > SWAPFILE_CLUSTER) {
VM_WARN_ON_ONCE(1);
return 0;
}
/*
* Swapfile is not block device so unable
* to allocate large entries.
*/
if (!(si->flags & SWP_BLKDEV))
return 0;
}
while (n_ret < nr) {
unsigned long offset = cluster_alloc_swap_entry(si, order, usage);
if (!offset)
break;
slots[n_ret++] = swp_entry(si->type, offset);
}
return n_ret;
}
static bool get_swap_device_info(struct swap_info_struct *si)
{
if (!percpu_ref_tryget_live(&si->users))
@ -1210,16 +1176,13 @@ static bool get_swap_device_info(struct swap_info_struct *si)
* Fast path try to get swap entries with specified order from current
* CPU's swap entry pool (a cluster).
*/
static int swap_alloc_fast(swp_entry_t entries[],
static int swap_alloc_fast(swp_entry_t *entry,
unsigned char usage,
int order, int n_goal)
int order)
{
struct swap_cluster_info *ci;
struct swap_info_struct *si;
unsigned int offset, found;
int n_ret = 0;
n_goal = min(n_goal, SWAP_BATCH);
unsigned int offset, found = SWAP_ENTRY_INVALID;
/*
* Once allocated, swap_info_struct will never be completely freed,
@ -1228,46 +1191,48 @@ static int swap_alloc_fast(swp_entry_t entries[],
si = this_cpu_read(percpu_swap_cluster.si[order]);
offset = this_cpu_read(percpu_swap_cluster.offset[order]);
if (!si || !offset || !get_swap_device_info(si))
return 0;
return false;
while (offset) {
ci = lock_cluster(si, offset);
if (!cluster_is_usable(ci, order)) {
unlock_cluster(ci);
break;
}
ci = lock_cluster(si, offset);
if (cluster_is_usable(ci, order)) {
if (cluster_is_empty(ci))
offset = cluster_offset(si, ci);
found = alloc_swap_scan_cluster(si, ci, offset, order, usage);
if (!found)
break;
entries[n_ret++] = swp_entry(si->type, found);
if (n_ret == n_goal)
break;
offset = this_cpu_read(percpu_swap_cluster.offset[order]);
if (found)
*entry = swp_entry(si->type, found);
} else {
unlock_cluster(ci);
}
put_swap_device(si);
return n_ret;
return !!found;
}
int get_swap_pages(int n_goal, swp_entry_t swp_entries[], int entry_order)
swp_entry_t folio_alloc_swap(struct folio *folio)
{
int order = swap_entry_order(entry_order);
unsigned long size = 1 << order;
unsigned int order = folio_order(folio);
unsigned int size = 1 << order;
struct swap_info_struct *si, *next;
int n_ret = 0;
swp_entry_t entry = {};
unsigned long offset;
int node;
if (order) {
/*
* Should not even be attempting large allocations when huge
* page swap is disabled. Warn and fail the allocation.
*/
if (!IS_ENABLED(CONFIG_THP_SWAP) || size > SWAPFILE_CLUSTER) {
VM_WARN_ON_ONCE(1);
return entry;
}
}
/* Fast path using percpu cluster */
local_lock(&percpu_swap_cluster.lock);
n_ret = swap_alloc_fast(swp_entries,
SWAP_HAS_CACHE,
order, n_goal);
if (n_ret == n_goal)
if (swap_alloc_fast(&entry, SWAP_HAS_CACHE, order))
goto out;
n_goal = min_t(int, n_goal - n_ret, SWAP_BATCH);
/* Rotate the device and switch to a new cluster */
spin_lock(&swap_avail_lock);
start_over:
@ -1276,18 +1241,13 @@ int get_swap_pages(int n_goal, swp_entry_t swp_entries[], int entry_order)
plist_requeue(&si->avail_lists[node], &swap_avail_heads[node]);
spin_unlock(&swap_avail_lock);
if (get_swap_device_info(si)) {
/*
* For order 0 allocation, try best to fill the request
* as it's used by slot cache.
*
* For mTHP allocation, it always have n_goal == 1,
* and falling a mTHP swapin will just make the caller
* fallback to order 0 allocation, so just bail out.
*/
n_ret += scan_swap_map_slots(si, SWAP_HAS_CACHE, n_goal,
swp_entries + n_ret, order);
offset = cluster_alloc_swap_entry(si, order, SWAP_HAS_CACHE);
put_swap_device(si);
if (n_ret || size > 1)
if (offset) {
entry = swp_entry(si->type, offset);
goto out;
}
if (order)
goto out;
}
@ -1309,8 +1269,14 @@ int get_swap_pages(int n_goal, swp_entry_t swp_entries[], int entry_order)
spin_unlock(&swap_avail_lock);
out:
local_unlock(&percpu_swap_cluster.lock);
atomic_long_sub(n_ret * size, &nr_swap_pages);
return n_ret;
/* Need to call this even if allocation failed, for MEMCG_SWAP_FAIL. */
if (mem_cgroup_try_charge_swap(folio, entry)) {
put_swap_folio(folio, entry);
entry.val = 0;
}
if (entry.val)
atomic_long_sub(size, &nr_swap_pages);
return entry;
}
static struct swap_info_struct *_swap_info_get(swp_entry_t entry)
@ -1606,25 +1572,6 @@ void put_swap_folio(struct folio *folio, swp_entry_t entry)
unlock_cluster(ci);
}
void swapcache_free_entries(swp_entry_t *entries, int n)
{
int i;
struct swap_cluster_info *ci;
struct swap_info_struct *si = NULL;
if (n <= 0)
return;
for (i = 0; i < n; ++i) {
si = _swap_info_get(entries[i]);
if (si) {
ci = lock_cluster(si, swp_offset(entries[i]));
swap_entry_range_free(si, ci, entries[i], 1);
unlock_cluster(ci);
}
}
}
int __swap_count(swp_entry_t entry)
{
struct swap_info_struct *si = swp_swap_info(entry);
@ -1865,6 +1812,7 @@ void free_swap_and_cache_nr(swp_entry_t entry, int nr)
swp_entry_t get_swap_page_of_type(int type)
{
struct swap_info_struct *si = swap_type_to_swap_info(type);
unsigned long offset;
swp_entry_t entry = {0};
if (!si)
@ -1872,8 +1820,13 @@ swp_entry_t get_swap_page_of_type(int type)
/* This is called for allocating swap entry, not cache */
if (get_swap_device_info(si)) {
if ((si->flags & SWP_WRITEOK) && scan_swap_map_slots(si, 1, 1, &entry, 0))
atomic_long_dec(&nr_swap_pages);
if (si->flags & SWP_WRITEOK) {
offset = cluster_alloc_swap_entry(si, 0, 1);
if (offset) {
entry = swp_entry(si->type, offset);
atomic_long_dec(&nr_swap_pages);
}
}
put_swap_device(si);
}
fail:
@ -2634,21 +2587,6 @@ static void reinsert_swap_info(struct swap_info_struct *si)
spin_unlock(&swap_lock);
}
static bool __has_usable_swap(void)
{
return !plist_head_empty(&swap_active_head);
}
bool has_usable_swap(void)
{
bool ret;
spin_lock(&swap_lock);
ret = __has_usable_swap();
spin_unlock(&swap_lock);
return ret;
}
/*
* Called after clearing SWP_WRITEOK, ensures cluster_alloc_range
* see the updated flags, so there will be no more allocations.
@ -2761,8 +2699,6 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
wait_for_allocation(p);
disable_swap_slots_cache_lock();
set_current_oom_origin();
err = try_to_unuse(p->type);
clear_current_oom_origin();
@ -2770,12 +2706,9 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
if (err) {
/* re-insert swap space back into swap_list */
reinsert_swap_info(p);
reenable_swap_slots_cache_unlock();
goto out_dput;
}
reenable_swap_slots_cache_unlock();
/*
* Wait for swap operations protected by get/put_swap_device()
* to complete. Because of synchronize_rcu() here, all swap
@ -3525,8 +3458,6 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
putname(name);
if (inode)
inode_unlock(inode);
if (!error)
enable_swap_slots_cache();
return error;
}
@ -3922,6 +3853,11 @@ static void free_swap_count_continuations(struct swap_info_struct *si)
}
#if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
static bool __has_usable_swap(void)
{
return !plist_head_empty(&swap_active_head);
}
void __folio_throttle_swaprate(struct folio *folio, gfp_t gfp)
{
struct swap_info_struct *si, *next;