Re: [PATCH v8 3/6] zswap: make shrinking memcg-aware

Yosry Ahmed
2023-12-05T18:21:13Z

On Thu, Nov 30, 2023 at 11:40 AM Nhat Pham <nphamcs@gmail.com> wrote:
>
> From: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
>
> Currently, we only have a single global LRU for zswap. This makes it
> impossible to perform worload-specific shrinking - an memcg cannot
> determine which pages in the pool it owns, and often ends up writing
> pages from other memcgs. This issue has been previously observed in
> practice and mitigated by simply disabling memcg-initiated shrinking:
>
> https://lore.kernel.org/all/20230530232435.3097106-1-nphamcs@gmail.com/T/#u
>
> This patch fully resolves the issue by replacing the global zswap LRU
> with memcg- and NUMA-specific LRUs, and modify the reclaim logic:
>
> a) When a store attempt hits an memcg limit, it now triggers a
> synchronous reclaim attempt that, if successful, allows the new
> hotter page to be accepted by zswap.
> b) If the store attempt instead hits the global zswap limit, it will
> trigger an asynchronous reclaim attempt, in which an memcg is
> selected for reclaim in a round-robin-like fashion.
>
> Signed-off-by: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
> Co-developed-by: Nhat Pham <nphamcs@gmail.com>
> Signed-off-by: Nhat Pham <nphamcs@gmail.com>
> ---
> include/linux/memcontrol.h | 5 +
> include/linux/zswap.h | 2 +
> mm/memcontrol.c | 2 +
> mm/swap.h | 3 +-
> mm/swap_state.c | 24 +++-
> mm/zswap.c | 269 +++++++++++++++++++++++++++++--------
> 6 files changed, 245 insertions(+), 60 deletions(-)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 2bd7d14ace78..a308c8eacf20 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -1192,6 +1192,11 @@ static inline struct mem_cgroup *page_memcg_check(struct page *page)
> return NULL;
> }
>
> +static inline struct mem_cgroup *get_mem_cgroup_from_objcg(struct obj_cgroup *objcg)
> +{
> + return NULL;
> +}
> +
> static inline bool folio_memcg_kmem(struct folio *folio)
> {
> return false;
> diff --git a/include/linux/zswap.h b/include/linux/zswap.h
> index 2a60ce39cfde..e571e393669b 100644
> --- a/include/linux/zswap.h
> +++ b/include/linux/zswap.h
> @@ -15,6 +15,7 @@ bool zswap_load(struct folio *folio);
> void zswap_invalidate(int type, pgoff_t offset);
> void zswap_swapon(int type);
> void zswap_swapoff(int type);
> +void zswap_memcg_offline_cleanup(struct mem_cgroup *memcg);
>
> #else
>
> @@ -31,6 +32,7 @@ static inline bool zswap_load(struct folio *folio)
> static inline void zswap_invalidate(int type, pgoff_t offset) {}
> static inline void zswap_swapon(int type) {}
> static inline void zswap_swapoff(int type) {}
> +static inline void zswap_memcg_offline_cleanup(struct mem_cgroup *memcg) {}
>
> #endif
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 470821d1ba1a..792ca21c5815 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -5614,6 +5614,8 @@ static void mem_cgroup_css_offline(struct cgroup_subsys_state *css)
> page_counter_set_min(&memcg->memory, 0);
> page_counter_set_low(&memcg->memory, 0);
>
> + zswap_memcg_offline_cleanup(memcg);
> +
> memcg_offline_kmem(memcg);
> reparent_shrinker_deferred(memcg);
> wb_memcg_offline(memcg);
> diff --git a/mm/swap.h b/mm/swap.h
> index 73c332ee4d91..c0dc73e10e91 100644
> --- a/mm/swap.h
> +++ b/mm/swap.h
> @@ -51,7 +51,8 @@ struct page *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
> struct swap_iocb **plug);
> struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
> struct mempolicy *mpol, pgoff_t ilx,
> - bool *new_page_allocated);
> + bool *new_page_allocated,
> + bool skip_if_exists);
> struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t flag,
> struct mempolicy *mpol, pgoff_t ilx);
> struct page *swapin_readahead(swp_entry_t entry, gfp_t flag,
> diff --git a/mm/swap_state.c b/mm/swap_state.c
> index 85d9e5806a6a..6c84236382f3 100644
> --- a/mm/swap_state.c
> +++ b/mm/swap_state.c
> @@ -412,7 +412,8 @@ struct folio *filemap_get_incore_folio(struct address_space *mapping,
>
> struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
> struct mempolicy *mpol, pgoff_t ilx,
> - bool *new_page_allocated)
> + bool *new_page_allocated,
> + bool skip_if_exists)
> {
> struct swap_info_struct *si;
> struct folio *folio;
> @@ -470,6 +471,17 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
> if (err != -EEXIST)
> goto fail_put_swap;
>
> + /*
> + * Protect against a recursive call to __read_swap_cache_async()
> + * on the same entry waiting forever here because SWAP_HAS_CACHE
> + * is set but the folio is not the swap cache yet. This can
> + * happen today if mem_cgroup_swapin_charge_folio() below
> + * triggers reclaim through zswap, which may call
> + * __read_swap_cache_async() in the writeback path.
> + */
> + if (skip_if_exists)
> + goto fail_put_swap;
> +
> /*
> * We might race against __delete_from_swap_cache(), and
> * stumble across a swap_map entry whose SWAP_HAS_CACHE
> @@ -537,7 +549,7 @@ struct page *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
>
> mpol = get_vma_policy(vma, addr, 0, &ilx);
> page = __read_swap_cache_async(entry, gfp_mask, mpol, ilx,
> - &page_allocated);
> + &page_allocated, false);
> mpol_cond_put(mpol);
>
> if (page_allocated)
> @@ -654,7 +666,7 @@ struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t gfp_mask,
> /* Ok, do the async read-ahead now */
> page = __read_swap_cache_async(
> swp_entry(swp_type(entry), offset),
> - gfp_mask, mpol, ilx, &page_allocated);
> + gfp_mask, mpol, ilx, &page_allocated, false);
> if (!page)
> continue;
> if (page_allocated) {
> @@ -672,7 +684,7 @@ struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t gfp_mask,
> skip:
> /* The page was likely read above, so no need for plugging here */
> page = __read_swap_cache_async(entry, gfp_mask, mpol, ilx,
> - &page_allocated);
> + &page_allocated, false);
> if (unlikely(page_allocated))
> swap_readpage(page, false, NULL);
> return page;
> @@ -827,7 +839,7 @@ static struct page *swap_vma_readahead(swp_entry_t targ_entry, gfp_t gfp_mask,
> pte_unmap(pte);
> pte = NULL;
> page = __read_swap_cache_async(entry, gfp_mask, mpol, ilx,
> - &page_allocated);
> + &page_allocated, false);
> if (!page)
> continue;
> if (page_allocated) {
> @@ -847,7 +859,7 @@ static struct page *swap_vma_readahead(swp_entry_t targ_entry, gfp_t gfp_mask,
> skip:
> /* The page was likely read above, so no need for plugging here */
> page = __read_swap_cache_async(targ_entry, gfp_mask, mpol, targ_ilx,
> - &page_allocated);
> + &page_allocated, false);
> if (unlikely(page_allocated))
> swap_readpage(page, false, NULL);
> return page;
> diff --git a/mm/zswap.c b/mm/zswap.c
> index 4bdb2d83bb0d..f323e45cbdc7 100644
> --- a/mm/zswap.c
> +++ b/mm/zswap.c
> @@ -35,6 +35,7 @@
> #include <linux/writeback.h>
> #include <linux/pagemap.h>
> #include <linux/workqueue.h>
> +#include <linux/list_lru.h>
>
> #include "swap.h"
> #include "internal.h"
> @@ -174,8 +175,8 @@ struct zswap_pool {
> struct work_struct shrink_work;
> struct hlist_node node;
> char tfm_name[CRYPTO_MAX_ALG_NAME];
> - struct list_head lru;
> - spinlock_t lru_lock;
> + struct list_lru list_lru;
> + struct mem_cgroup *next_shrink;
> };
>
> /*
> @@ -291,15 +292,46 @@ static void zswap_update_total_size(void)
> zswap_pool_total_size = total;
> }
>
> +/* should be called under RCU */

nit: probably WARN_ON_ONCE(!rcu_read_lock_held()) or
RCU_LOCKDEP_WARN(!rcu_read_lock_held()) in the function body is
better?

> +#ifdef CONFIG_MEMCG
> +static inline struct mem_cgroup *mem_cgroup_from_entry(struct zswap_entry *entry)
> +{
> + return entry->objcg ? obj_cgroup_memcg(entry->objcg) : NULL;
> +}
> +#else
> +static inline struct mem_cgroup *mem_cgroup_from_entry(struct zswap_entry *entry)
> +{
> + return NULL;
> +}
> +#endif
> +
> +static inline int entry_to_nid(struct zswap_entry *entry)
> +{
> + return page_to_nid(virt_to_page(entry));
> +}
> +
> +void zswap_memcg_offline_cleanup(struct mem_cgroup *memcg)
> +{
> + struct zswap_pool *pool;
> +
> + /* lock out zswap pools list modification */
> + spin_lock(&zswap_pools_lock);
> + list_for_each_entry(pool, &zswap_pools, list) {
> + if (pool->next_shrink == memcg)
> + pool->next_shrink = mem_cgroup_iter(NULL, pool->next_shrink, NULL);
> + }
> + spin_unlock(&zswap_pools_lock);
> +}
> +
> /*********************************
> * zswap entry functions
> **********************************/
> static struct kmem_cache *zswap_entry_cache;
>
> -static struct zswap_entry *zswap_entry_cache_alloc(gfp_t gfp)
> +static struct zswap_entry *zswap_entry_cache_alloc(gfp_t gfp, int nid)
> {
> struct zswap_entry *entry;
> - entry = kmem_cache_alloc(zswap_entry_cache, gfp);
> + entry = kmem_cache_alloc_node(zswap_entry_cache, gfp, nid);
> if (!entry)
> return NULL;
> entry->refcount = 1;
> @@ -312,6 +344,61 @@ static void zswap_entry_cache_free(struct zswap_entry *entry)
> kmem_cache_free(zswap_entry_cache, entry);
> }
>
> +/*********************************
> +* lru functions
> +**********************************/
> +static void zswap_lru_add(struct list_lru *list_lru, struct zswap_entry *entry)
> +{
> + int nid = entry_to_nid(entry);
> + struct mem_cgroup *memcg;
> +
> + /*
> + * Note that it is safe to use rcu_read_lock() here, even in the face of
> + * concurrent memcg offlining. Thanks to the memcg->kmemcg_id indirection
> + * used in list_lru lookup, only two scenarios are possible:
> + *
> + * 1. list_lru_add() is called before memcg->kmemcg_id is updated. The
> + * new entry will be reparented to memcg's parent's list_lru.
> + * 2. list_lru_add() is called after memcg->kmemcg_id is updated. The
> + * new entry will be added directly to memcg's parent's list_lru.
> + *
> + * Similar reasoning holds for list_lru_del() and list_lru_putback().
> + */
> + rcu_read_lock();
> + memcg = mem_cgroup_from_entry(entry);
> + /* will always succeed */
> + list_lru_add(list_lru, &entry->lru, nid, memcg);
> + rcu_read_unlock();
> +}
> +
> +static void zswap_lru_del(struct list_lru *list_lru, struct zswap_entry *entry)
> +{
> + int nid = entry_to_nid(entry);
> + struct mem_cgroup *memcg;
> +
> + rcu_read_lock();
> + memcg = mem_cgroup_from_entry(entry);
> + /* will always succeed */
> + list_lru_del(list_lru, &entry->lru, nid, memcg);
> + rcu_read_unlock();
> +}
> +
> +static void zswap_lru_putback(struct list_lru *list_lru,
> + struct zswap_entry *entry)
> +{
> + int nid = entry_to_nid(entry);
> + spinlock_t *lock = &list_lru->node[nid].lock;
> + struct mem_cgroup *memcg;
> +
> + rcu_read_lock();
> + memcg = mem_cgroup_from_entry(entry);
> + spin_lock(lock);
> + /* we cannot use list_lru_add here, because it increments node's lru count */
> + list_lru_putback(list_lru, &entry->lru, nid, memcg);
> + spin_unlock(lock);
> + rcu_read_unlock();
> +}
> +
> /*********************************
> * rbtree functions
> **********************************/
> @@ -396,9 +483,7 @@ static void zswap_free_entry(struct zswap_entry *entry)
> if (!entry->length)
> atomic_dec(&zswap_same_filled_pages);
> else {
> - spin_lock(&entry->pool->lru_lock);
> - list_del(&entry->lru);
> - spin_unlock(&entry->pool->lru_lock);
> + zswap_lru_del(&entry->pool->list_lru, entry);
> zpool_free(zswap_find_zpool(entry), entry->handle);
> zswap_pool_put(entry->pool);
> }
> @@ -632,21 +717,15 @@ static void zswap_invalidate_entry(struct zswap_tree *tree,
> zswap_entry_put(tree, entry);
> }
>
> -static int zswap_reclaim_entry(struct zswap_pool *pool)
> +static enum lru_status shrink_memcg_cb(struct list_head *item, struct list_lru_one *l,
> + spinlock_t *lock, void *arg)
> {
> - struct zswap_entry *entry;
> + struct zswap_entry *entry = container_of(item, struct zswap_entry, lru);
> struct zswap_tree *tree;
> pgoff_t swpoffset;
> - int ret;
> + enum lru_status ret = LRU_REMOVED_RETRY;
> + int writeback_result;
>
> - /* Get an entry off the LRU */
> - spin_lock(&pool->lru_lock);
> - if (list_empty(&pool->lru)) {
> - spin_unlock(&pool->lru_lock);
> - return -EINVAL;
> - }
> - entry = list_last_entry(&pool->lru, struct zswap_entry, lru);
> - list_del_init(&entry->lru);
> /*
> * Once the lru lock is dropped, the entry might get freed. The
> * swpoffset is copied to the stack, and entry isn't deref'd again
> @@ -654,28 +733,32 @@ static int zswap_reclaim_entry(struct zswap_pool *pool)
> */
> swpoffset = swp_offset(entry->swpentry);
> tree = zswap_trees[swp_type(entry->swpentry)];
> - spin_unlock(&pool->lru_lock);
> + list_lru_isolate(l, item);
> + /*
> + * It's safe to drop the lock here because we return either
> + * LRU_REMOVED_RETRY or LRU_RETRY.
> + */
> + spin_unlock(lock);
>
> /* Check for invalidate() race */
> spin_lock(&tree->lock);
> - if (entry != zswap_rb_search(&tree->rbroot, swpoffset)) {
> - ret = -EAGAIN;
> + if (entry != zswap_rb_search(&tree->rbroot, swpoffset))
> goto unlock;
> - }
> +
> /* Hold a reference to prevent a free during writeback */
> zswap_entry_get(entry);
> spin_unlock(&tree->lock);
>
> - ret = zswap_writeback_entry(entry, tree);
> + writeback_result = zswap_writeback_entry(entry, tree);
>
> spin_lock(&tree->lock);
> - if (ret) {
> - /* Writeback failed, put entry back on LRU */
> - spin_lock(&pool->lru_lock);
> - list_move(&entry->lru, &pool->lru);
> - spin_unlock(&pool->lru_lock);
> + if (writeback_result) {
> + zswap_reject_reclaim_fail++;
> + zswap_lru_putback(&entry->pool->list_lru, entry);
> + ret = LRU_RETRY;
> goto put_unlock;
> }
> + zswap_written_back_pages++;
>
> /*
> * Writeback started successfully, the page now belongs to the
> @@ -689,27 +772,93 @@ static int zswap_reclaim_entry(struct zswap_pool *pool)
> zswap_entry_put(tree, entry);
> unlock:
> spin_unlock(&tree->lock);
> - return ret ? -EAGAIN : 0;
> + spin_lock(lock);
> + return ret;
> +}
> +
> +static int shrink_memcg(struct mem_cgroup *memcg)
> +{
> + struct zswap_pool *pool;
> + int nid, shrunk = 0;
> +
> + /*
> + * Skip zombies because their LRUs are reparented and we would be
> + * reclaiming from the parent instead of the dead memcg.
> + */
> + if (memcg && !mem_cgroup_online(memcg))
> + return -ENOENT;
> +
> + pool = zswap_pool_current_get();
> + if (!pool)
> + return -EINVAL;
> +
> + for_each_node_state(nid, N_NORMAL_MEMORY) {
> + unsigned long nr_to_walk = 1;
> +
> + shrunk += list_lru_walk_one(&pool->list_lru, nid, memcg,
> + &shrink_memcg_cb, NULL, &nr_to_walk);
> + }
> + zswap_pool_put(pool);
> + return shrunk ? 0 : -EAGAIN;
> }
>
> static void shrink_worker(struct work_struct *w)
> {
> struct zswap_pool *pool = container_of(w, typeof(*pool),
> shrink_work);
> + struct mem_cgroup *memcg;
> int ret, failures = 0;
>
> + /* global reclaim will select cgroup in a round-robin fashion. */
> do {
> - ret = zswap_reclaim_entry(pool);
> - if (ret) {
> - zswap_reject_reclaim_fail++;
> - if (ret != -EAGAIN)
> + spin_lock(&zswap_pools_lock);
> + pool->next_shrink = mem_cgroup_iter(NULL, pool->next_shrink, NULL);
> + memcg = pool->next_shrink;
> +
> + /*
> + * We need to retry if we have gone through a full round trip, or if we
> + * got an offline memcg (or else we risk undoing the effect of the
> + * zswap memcg offlining cleanup callback). This is not catastrophic
> + * per se, but it will keep the now offlined memcg hostage for a while.
> + *
> + * Note that if we got an online memcg, we will keep the extra
> + * reference in case the original reference obtained by mem_cgroup_iter
> + * is dropped by the zswap memcg offlining callback, ensuring that the
> + * memcg is not killed when we are reclaiming.
> + */
> + if (!memcg) {
> + spin_unlock(&zswap_pools_lock);
> + if (++failures == MAX_RECLAIM_RETRIES)
> break;
> +
> + goto resched;
> + }
> +
> + if (!mem_cgroup_online(memcg)) {
> + /* drop the reference from mem_cgroup_iter() */
> + mem_cgroup_put(memcg);

Probably better to use mem_cgroup_iter_break() here?

Also, I don't see mem_cgroup_tryget_online() being used here (where I
expected it to be used), did I miss it?

> + pool->next_shrink = NULL;
> + spin_unlock(&zswap_pools_lock);
> +
> if (++failures == MAX_RECLAIM_RETRIES)
> break;
> +
> + goto resched;
> }
> + spin_unlock(&zswap_pools_lock);
> +
> + ret = shrink_memcg(memcg);

We just checked for online-ness above, and then shrink_memcg() checks
it again. Is this intentional?

> + /* drop the extra reference */

Where does the extra reference come from?

> + mem_cgroup_put(memcg);
> +
> + if (ret == -EINVAL)
> + break;
> + if (ret && ++failures == MAX_RECLAIM_RETRIES)
> + break;
> +
> +resched:
> cond_resched();
> } while (!zswap_can_accept());
> - zswap_pool_put(pool);
> }
>
> static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
> @@ -767,8 +916,7 @@ static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
> */
> kref_init(&pool->kref);
> INIT_LIST_HEAD(&pool->list);
> - INIT_LIST_HEAD(&pool->lru);
> - spin_lock_init(&pool->lru_lock);
> + list_lru_init_memcg(&pool->list_lru, NULL);
> INIT_WORK(&pool->shrink_work, shrink_worker);
>
> zswap_pool_debug("created", pool);
> @@ -834,6 +982,13 @@ static void zswap_pool_destroy(struct zswap_pool *pool)
>
> cpuhp_state_remove_instance(CPUHP_MM_ZSWP_POOL_PREPARE, &pool->node);
> free_percpu(pool->acomp_ctx);
> + list_lru_destroy(&pool->list_lru);
> +
> + spin_lock(&zswap_pools_lock);
> + mem_cgroup_put(pool->next_shrink);
> + pool->next_shrink = NULL;
> + spin_unlock(&zswap_pools_lock);
> +
> for (i = 0; i < ZSWAP_NR_ZPOOLS; i++)
> zpool_destroy_pool(pool->zpools[i]);
> kfree(pool);
> @@ -1081,7 +1236,7 @@ static int zswap_writeback_entry(struct zswap_entry *entry,
> /* try to allocate swap cache page */
> mpol = get_task_policy(current);
> page = __read_swap_cache_async(swpentry, GFP_KERNEL, mpol,
> - NO_INTERLEAVE_INDEX, &page_was_allocated);
> + NO_INTERLEAVE_INDEX, &page_was_allocated, true);
> if (!page) {
> ret = -ENOMEM;
> goto fail;
> @@ -1152,7 +1307,6 @@ static int zswap_writeback_entry(struct zswap_entry *entry,
> /* start writeback */
> __swap_writepage(page, &wbc);
> put_page(page);
> - zswap_written_back_pages++;
>
> return ret;
>
> @@ -1209,6 +1363,7 @@ bool zswap_store(struct folio *folio)
> struct scatterlist input, output;
> struct crypto_acomp_ctx *acomp_ctx;
> struct obj_cgroup *objcg = NULL;
> + struct mem_cgroup *memcg = NULL;
> struct zswap_pool *pool;
> struct zpool *zpool;
> unsigned int dlen = PAGE_SIZE;
> @@ -1240,15 +1395,15 @@ bool zswap_store(struct folio *folio)
> zswap_invalidate_entry(tree, dupentry);
> }
> spin_unlock(&tree->lock);
> -
> - /*
> - * XXX: zswap reclaim does not work with cgroups yet. Without a
> - * cgroup-aware entry LRU, we will push out entries system-wide based on
> - * local cgroup limits.
> - */
> objcg = get_obj_cgroup_from_folio(folio);
> - if (objcg && !obj_cgroup_may_zswap(objcg))
> - goto reject;
> + if (objcg && !obj_cgroup_may_zswap(objcg)) {
> + memcg = get_mem_cgroup_from_objcg(objcg);

Do we need a reference here? IIUC, this is folio_memcg() and the folio
is locked, so folio_memcg() should remain stable, no?

Same for the call below.

> + if (shrink_memcg(memcg)) {
> + mem_cgroup_put(memcg);
> + goto reject;
> + }
> + mem_cgroup_put(memcg);
> + }
>
> /* reclaim space if needed */
> if (zswap_is_full()) {
> @@ -1265,7 +1420,7 @@ bool zswap_store(struct folio *folio)
> }
>
> /* allocate entry */
> - entry = zswap_entry_cache_alloc(GFP_KERNEL);
> + entry = zswap_entry_cache_alloc(GFP_KERNEL, page_to_nid(page));
> if (!entry) {
> zswap_reject_kmemcache_fail++;
> goto reject;
> @@ -1292,6 +1447,15 @@ bool zswap_store(struct folio *folio)
> if (!entry->pool)
> goto freepage;
>
> + if (objcg) {
> + memcg = get_mem_cgroup_from_objcg(objcg);
> + if (memcg_list_lru_alloc(memcg, &entry->pool->list_lru, GFP_KERNEL)) {
> + mem_cgroup_put(memcg);
> + goto put_pool;
> + }
> + mem_cgroup_put(memcg);
> + }
> +
> /* compress */
> acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx);
>
> @@ -1370,9 +1534,8 @@ bool zswap_store(struct folio *folio)
> zswap_invalidate_entry(tree, dupentry);
> }
> if (entry->length) {
> - spin_lock(&entry->pool->lru_lock);
> - list_add(&entry->lru, &entry->pool->lru);
> - spin_unlock(&entry->pool->lru_lock);
> + INIT_LIST_HEAD(&entry->lru);
> + zswap_lru_add(&entry->pool->list_lru, entry);
> }
> spin_unlock(&tree->lock);
>
> @@ -1385,6 +1548,7 @@ bool zswap_store(struct folio *folio)
>
> put_dstmem:
> mutex_unlock(acomp_ctx->mutex);
> +put_pool:
> zswap_pool_put(entry->pool);
> freepage:
> zswap_entry_cache_free(entry);
> @@ -1479,9 +1643,8 @@ bool zswap_load(struct folio *folio)
> zswap_invalidate_entry(tree, entry);
> folio_mark_dirty(folio);
> } else if (entry->length) {
> - spin_lock(&entry->pool->lru_lock);
> - list_move(&entry->lru, &entry->pool->lru);
> - spin_unlock(&entry->pool->lru_lock);
> + zswap_lru_del(&entry->pool->list_lru, entry);
> + zswap_lru_add(&entry->pool->list_lru, entry);
> }
> zswap_entry_put(tree, entry);
> spin_unlock(&tree->lock);
> --
> 2.34.1