On Wed, Sep 27, 2023 at 12:48 PM Domenico Cerasuolo <cerasuolodomenico@xxxxxxxxx> wrote: > > On Mon, Sep 25, 2023 at 10:17 PM Yosry Ahmed <yosryahmed@xxxxxxxxxx> wrote: > > > > +Chris Li > > > > On Tue, Sep 19, 2023 at 10:14 AM Nhat Pham <nphamcs@xxxxxxxxx> wrote: > > > > > > From: Domenico Cerasuolo <cerasuolodomenico@xxxxxxxxx> > > > > > > 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@xxxxxxxxx/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. > > > > Hey Nhat, > > > > I didn't take a very close look as I am currently swamped, but going > > through the patch I have some comments/questions below. > > > > I am not very familiar with list_lru, but it seems like the existing > > API derives the node and memcg from the list item itself. Seems like > > we can avoid a lot of changes if we allocate struct zswap_entry from > > the same node as the page, and account it to the same memcg. Would > > this be too much of a change or too strong of a restriction? It's a > > slab allocation and we will free memory on that node/memcg right > > after. > > > > > > > > Signed-off-by: Domenico Cerasuolo <cerasuolodomenico@xxxxxxxxx> > > > Co-developed-by: Nhat Pham <nphamcs@xxxxxxxxx> > > > Signed-off-by: Nhat Pham <nphamcs@xxxxxxxxx> > > > --- > > > include/linux/list_lru.h | 39 +++++++ > > > include/linux/memcontrol.h | 5 + > > > include/linux/zswap.h | 9 ++ > > > mm/list_lru.c | 46 ++++++-- > > > mm/swap_state.c | 19 ++++ > > > mm/zswap.c | 221 +++++++++++++++++++++++++++++-------- > > > 6 files changed, 287 insertions(+), 52 deletions(-) > > > > > > diff --git a/include/linux/list_lru.h b/include/linux/list_lru.h > > > index b35968ee9fb5..b517b4e2c7c4 100644 > > > --- a/include/linux/list_lru.h > > > +++ b/include/linux/list_lru.h > > > @@ -89,6 +89,24 @@ void memcg_reparent_list_lrus(struct mem_cgroup *memcg, struct mem_cgroup *paren > > > */ > > > bool list_lru_add(struct list_lru *lru, struct list_head *item); > > > > > > +/** > > > + * __list_lru_add: add an element to a specific sublist. > > > + * @list_lru: the lru pointer > > > + * @item: the item to be added. > > > + * @memcg: the cgroup of the sublist to add the item to. > > > + * @nid: the node id of the sublist to add the item to. > > > + * > > > + * This function is similar to list_lru_add(), but it allows the caller to > > > + * specify the sublist to which the item should be added. This can be useful > > > + * when the list_head node is not necessarily in the same cgroup and NUMA node > > > + * as the data it represents, such as zswap, where the list_head node could be > > > + * from kswapd and the data from a different cgroup altogether. > > > + * > > > + * Return value: true if the list was updated, false otherwise > > > + */ > > > +bool __list_lru_add(struct list_lru *lru, struct list_head *item, int nid, > > > + struct mem_cgroup *memcg); > > > + > > > /** > > > * list_lru_del: delete an element to the lru list > > > * @list_lru: the lru pointer > > > @@ -102,6 +120,18 @@ bool list_lru_add(struct list_lru *lru, struct list_head *item); > > > */ > > > bool list_lru_del(struct list_lru *lru, struct list_head *item); > > > > > > +/** > > > + * __list_lru_delete: delete an element from a specific sublist. > > > + * @list_lru: the lru pointer > > > + * @item: the item to be deleted. > > > + * @memcg: the cgroup of the sublist to delete the item from. > > > + * @nid: the node id of the sublist to delete the item from. > > > + * > > > + * Return value: true if the list was updated, false otherwise. > > > + */ > > > +bool __list_lru_del(struct list_lru *lru, struct list_head *item, int nid, > > > + struct mem_cgroup *memcg); > > > + > > > /** > > > * list_lru_count_one: return the number of objects currently held by @lru > > > * @lru: the lru pointer. > > > @@ -137,6 +167,15 @@ void list_lru_isolate(struct list_lru_one *list, struct list_head *item); > > > void list_lru_isolate_move(struct list_lru_one *list, struct list_head *item, > > > struct list_head *head); > > > > > > +/* > > > + * list_lru_putback: undo list_lru_isolate. > > > + * > > > + * Since we might have dropped the LRU lock in between, recompute list_lru_one > > > + * from the node's id and memcg. > > > + */ > > > +void list_lru_putback(struct list_lru *lru, struct list_head *item, int nid, > > > + struct mem_cgroup *memcg); > > > + > > > typedef enum lru_status (*list_lru_walk_cb)(struct list_head *item, > > > struct list_lru_one *list, spinlock_t *lock, void *cb_arg); > > > > > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > > > index 67b823dfa47d..05d34b328d9d 100644 > > > --- a/include/linux/memcontrol.h > > > +++ b/include/linux/memcontrol.h > > > @@ -1179,6 +1179,11 @@ 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..04f80b64a09b 100644 > > > --- a/include/linux/zswap.h > > > +++ b/include/linux/zswap.h > > > @@ -15,6 +15,8 @@ bool zswap_load(struct folio *folio); > > > void zswap_invalidate(int type, pgoff_t offset); > > > void zswap_swapon(int type); > > > void zswap_swapoff(int type); > > > +bool zswap_remove_swpentry_from_lru(swp_entry_t swpentry); > > > +void zswap_insert_swpentry_into_lru(swp_entry_t swpentry); > > > > > > #else > > > > > > @@ -32,6 +34,13 @@ 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 bool zswap_remove_swpentry_from_lru(swp_entry_t swpentry) > > > +{ > > > + return false; > > > +} > > > + > > > +static inline void zswap_insert_swpentry_into_lru(swp_entry_t swpentry) {} > > > + > > > #endif > > > > > > #endif /* _LINUX_ZSWAP_H */ > > > diff --git a/mm/list_lru.c b/mm/list_lru.c > > > index a05e5bef3b40..37c5c2ef6c0e 100644 > > > --- a/mm/list_lru.c > > > +++ b/mm/list_lru.c > > > @@ -119,18 +119,26 @@ list_lru_from_kmem(struct list_lru *lru, int nid, void *ptr, > > > bool list_lru_add(struct list_lru *lru, struct list_head *item) > > > { > > > int nid = page_to_nid(virt_to_page(item)); > > > + struct mem_cgroup *memcg = list_lru_memcg_aware(lru) ? > > > + mem_cgroup_from_slab_obj(item) : NULL; > > > + > > > + return __list_lru_add(lru, item, nid, memcg); > > > +} > > > +EXPORT_SYMBOL_GPL(list_lru_add); > > > + > > > +bool __list_lru_add(struct list_lru *lru, struct list_head *item, int nid, > > > + struct mem_cgroup *memcg) > > > +{ > > > struct list_lru_node *nlru = &lru->node[nid]; > > > - struct mem_cgroup *memcg; > > > struct list_lru_one *l; > > > > > > spin_lock(&nlru->lock); > > > if (list_empty(item)) { > > > - l = list_lru_from_kmem(lru, nid, item, &memcg); > > > + l = list_lru_from_memcg_idx(lru, nid, memcg_kmem_id(memcg)); > > > list_add_tail(item, &l->list); > > > /* Set shrinker bit if the first element was added */ > > > if (!l->nr_items++) > > > - set_shrinker_bit(memcg, nid, > > > - lru_shrinker_id(lru)); > > > + set_shrinker_bit(memcg, nid, lru_shrinker_id(lru)); > > > > Unrelated diff. > > > > > nlru->nr_items++; > > > spin_unlock(&nlru->lock); > > > return true; > > > @@ -138,17 +146,27 @@ bool list_lru_add(struct list_lru *lru, struct list_head *item) > > > spin_unlock(&nlru->lock); > > > return false; > > > } > > > -EXPORT_SYMBOL_GPL(list_lru_add); > > > +EXPORT_SYMBOL_GPL(__list_lru_add); > > > > > > bool list_lru_del(struct list_lru *lru, struct list_head *item) > > > { > > > int nid = page_to_nid(virt_to_page(item)); > > > + struct mem_cgroup *memcg = list_lru_memcg_aware(lru) ? > > > + mem_cgroup_from_slab_obj(item) : NULL; > > > + > > > + return __list_lru_del(lru, item, nid, memcg); > > > +} > > > +EXPORT_SYMBOL_GPL(list_lru_del); > > > + > > > +bool __list_lru_del(struct list_lru *lru, struct list_head *item, int nid, > > > + struct mem_cgroup *memcg) > > > +{ > > > struct list_lru_node *nlru = &lru->node[nid]; > > > struct list_lru_one *l; > > > > > > spin_lock(&nlru->lock); > > > if (!list_empty(item)) { > > > - l = list_lru_from_kmem(lru, nid, item, NULL); > > > > If we decide to keep the list_lru.c changes, do we have any other > > callers of list_lru_from_kmem()? > > I see a commit already in mm-unstable that removes it. > > > > > > + l = list_lru_from_memcg_idx(lru, nid, memcg_kmem_id(memcg)); > > > list_del_init(item); > > > l->nr_items--; > > > nlru->nr_items--; > > > @@ -158,7 +176,7 @@ bool list_lru_del(struct list_lru *lru, struct list_head *item) > > > spin_unlock(&nlru->lock); > > > return false; > > > } > > > -EXPORT_SYMBOL_GPL(list_lru_del); > > > +EXPORT_SYMBOL_GPL(__list_lru_del); > > > > > > void list_lru_isolate(struct list_lru_one *list, struct list_head *item) > > > { > > > @@ -175,6 +193,20 @@ void list_lru_isolate_move(struct list_lru_one *list, struct list_head *item, > > > } > > > EXPORT_SYMBOL_GPL(list_lru_isolate_move); > > > > > > +void list_lru_putback(struct list_lru *lru, struct list_head *item, int nid, > > > + struct mem_cgroup *memcg) > > > +{ > > > + struct list_lru_one *list = > > > + list_lru_from_memcg_idx(lru, nid, memcg_kmem_id(memcg)); > > > + > > > + if (list_empty(item)) { > > > + list_add_tail(item, &list->list); > > > + if (!list->nr_items++) > > > + set_shrinker_bit(memcg, nid, lru_shrinker_id(lru)); > > > + } > > > +} > > > +EXPORT_SYMBOL_GPL(list_lru_putback); > > > + > > > unsigned long list_lru_count_one(struct list_lru *lru, > > > int nid, struct mem_cgroup *memcg) > > > { > > > diff --git a/mm/swap_state.c b/mm/swap_state.c > > > index b3b14bd0dd64..1c826737aacb 100644 > > > --- a/mm/swap_state.c > > > +++ b/mm/swap_state.c > > > @@ -21,6 +21,7 @@ > > > #include <linux/swap_slots.h> > > > #include <linux/huge_mm.h> > > > #include <linux/shmem_fs.h> > > > +#include <linux/zswap.h> > > > #include "internal.h" > > > #include "swap.h" > > > > > > @@ -417,6 +418,7 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask, > > > struct folio *folio; > > > struct page *page; > > > void *shadow = NULL; > > > + bool zswap_lru_removed = false; > > > > > > *new_page_allocated = false; > > > si = get_swap_device(entry); > > > @@ -485,6 +487,17 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask, > > > __folio_set_locked(folio); > > > __folio_set_swapbacked(folio); > > > > > > + /* > > > + * Page fault might itself trigger reclaim, on a zswap object that > > > + * corresponds to the same swap entry. However, as the swap entry has > > > + * previously been pinned, the task will run into an infinite loop trying > > > + * to pin the swap entry again. > > > + * > > > + * To prevent this from happening, we remove it from the zswap > > > + * LRU to prevent its reclamation. > > > + */ > > > + zswap_lru_removed = zswap_remove_swpentry_from_lru(entry); > > > + > > > > This will add a zswap lookup (and potentially an insertion below) in > > every single swap fault path, right?. Doesn't this introduce latency > > regressions? I am also not a fan of having zswap-specific details in > > this path. > > > > When you say "pinned", do you mean the call to swapcache_prepare() > > above (i.e. setting SWAP_HAS_CACHE)? IIUC, the scenario you are > > worried about is that the following call to charge the page may invoke > > reclaim, go into zswap, and try to writeback the same page we are > > swapping in here. The writeback call will recurse into > > __read_swap_cache_async(), call swapcache_prepare() and get EEXIST, > > and keep looping indefinitely. Is this correct? > > > > If yes, can we handle this by adding a flag to > > __read_swap_cache_async() that basically says "don't wait for > > SWAP_HAS_CACHE and the swapcache to be consistent, if > > swapcache_prepare() returns EEXIST just fail and return"? The zswap > > writeback path can pass in this flag and skip such pages. We might > > want to modify the writeback code to put back those pages at the end > > of the lru instead of in the beginning. > > Thanks for the suggestion, this actually works and it seems cleaner so I think > we'll go for your solution. > > > > > > if (mem_cgroup_swapin_charge_folio(folio, NULL, gfp_mask, entry)) > > > goto fail_unlock; > > > > > > @@ -497,6 +510,9 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask, > > > if (shadow) > > > workingset_refault(folio, shadow); > > > > > > + if (zswap_lru_removed) > > > + zswap_insert_swpentry_into_lru(entry); > > > + > > > /* Caller will initiate read into locked folio */ > > > folio_add_lru(folio); > > > *new_page_allocated = true; > > > @@ -506,6 +522,9 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask, > > > return page; > > > > > > fail_unlock: > > > + if (zswap_lru_removed) > > > + zswap_insert_swpentry_into_lru(entry); > > > + > > > put_swap_folio(folio, entry); > > > folio_unlock(folio); > > > folio_put(folio); > > > diff --git a/mm/zswap.c b/mm/zswap.c > > > index 412b1409a0d7..1a469e5d5197 100644 > > > --- a/mm/zswap.c > > > +++ b/mm/zswap.c > > > @@ -34,6 +34,7 @@ > > > #include <linux/writeback.h> > > > #include <linux/pagemap.h> > > > #include <linux/workqueue.h> > > > +#include <linux/list_lru.h> > > > > > > #include "swap.h" > > > #include "internal.h" > > > @@ -171,8 +172,8 @@ 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; > > > }; > > > > > > /* > > > @@ -209,6 +210,7 @@ struct zswap_entry { > > > unsigned long value; > > > }; > > > struct obj_cgroup *objcg; > > > + int nid; > > > struct list_head lru; > > > }; > > > > Ideally this can be avoided if we can allocate struct zswap_entry on > > the correct node. > > We didn't consider allocating the entry on the node without charging it to the > memcg, we'll try it and if it's doable it would be a good compromise to avoid > adding the node id here. > > > > > > > > > @@ -309,6 +311,29 @@ static void zswap_entry_cache_free(struct zswap_entry *entry) > > > kmem_cache_free(zswap_entry_cache, entry); > > > } > > > > > > +/********************************* > > > +* lru functions > > > +**********************************/ > > > +static bool zswap_lru_add(struct list_lru *list_lru, struct zswap_entry *entry) > > > +{ > > > + struct mem_cgroup *memcg = entry->objcg ? > > > + get_mem_cgroup_from_objcg(entry->objcg) : NULL; > > > > This line is repeated at least 3 times, perhaps add a helper for it? > > get_mem_cgroup_from_zswap()? > > > > > + bool added = __list_lru_add(list_lru, &entry->lru, entry->nid, memcg); > > > + > > > + mem_cgroup_put(memcg); > > > + return added; > > > +} > > > + > > > +static bool zswap_lru_del(struct list_lru *list_lru, struct zswap_entry *entry) > > > +{ > > > + struct mem_cgroup *memcg = entry->objcg ? > > > + get_mem_cgroup_from_objcg(entry->objcg) : NULL; > > > + bool removed = __list_lru_del(list_lru, &entry->lru, entry->nid, memcg); > > > + > > > + mem_cgroup_put(memcg); > > > + return removed; > > > +} > > > + > > > /********************************* > > > * rbtree functions > > > **********************************/ > > > @@ -393,9 +418,7 @@ 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); > > > } > > > @@ -629,21 +652,16 @@ 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 mem_cgroup *memcg; > > > 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 > > > @@ -651,26 +669,35 @@ 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); > > > + spin_unlock(lock); > > > > > > /* Check for invalidate() race */ > > > spin_lock(&tree->lock); > > > if (entry != zswap_rb_search(&tree->rbroot, swpoffset)) { > > > - ret = -EAGAIN; > > > 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++; > > > + > > > + /* Check for invalidate() race */ > > > + if (entry != zswap_rb_search(&tree->rbroot, swpoffset)) > > > + goto put_unlock; > > > + > > > + memcg = entry->objcg ? get_mem_cgroup_from_objcg(entry->objcg) : NULL; > > > + spin_lock(lock); > > > + /* we cannot use zswap_lru_add here, because it increments node's lru count */ > > > + list_lru_putback(&entry->pool->list_lru, item, entry->nid, memcg); > > > + spin_unlock(lock); > > > + mem_cgroup_put(memcg); > > > + ret = LRU_RETRY; > > > goto put_unlock; > > > } > > > > > > @@ -686,19 +713,63 @@ 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; > > > + bool is_empty = true; > > > + > > > + pool = zswap_pool_current_get(); > > > + if (!pool) > > > + return -EINVAL; > > > + > > > + for_each_node_state(nid, N_NORMAL_MEMORY) { > > > + unsigned long nr_to_walk = 1; > > > + > > > + if (list_lru_walk_one(&pool->list_lru, nid, memcg, &shrink_memcg_cb, > > > + NULL, &nr_to_walk)) > > > + shrunk++; > > > + if (!nr_to_walk) > > > > nr_to_walk will be 0 if we shrunk 1 page, so it's the same condition > > as the above, right? > > > > is_empty seems to be shrunk == 0 if I understand correctly, seems like > > there is no need for both. > > It is indeed 0 when we shrunk 1 page, but it could also be 0 also when the > reclaim failed and the list was not empty. I see. I still think the function can be clearer / more aesthetic, but I don't really know how off the top of my head :) > > > > > > + is_empty = false; > > > + } > > > + zswap_pool_put(pool); > > > + > > > + if (is_empty) > > > + return -EINVAL; > > > + if (shrunk) > > > + return 0; > > > + return -EAGAIN; > > > } > > > > > > static void shrink_worker(struct work_struct *w) > > > { > > > struct zswap_pool *pool = container_of(w, typeof(*pool), > > > shrink_work); > > > - int ret, failures = 0; > > > + int ret, failures = 0, memcg_selection_failures = 0; > > > > > > + /* global reclaim will select cgroup in a round-robin fashion. */ > > > do { > > > - ret = zswap_reclaim_entry(pool); > > > + /* previous next_shrink has become a zombie - restart from the top */ > > > > Do we skip zombies because all zswap entries are reparented with the objcg? > > > > If yes, why do we restart from the top instead of just skipping them? > > memcgs after a zombie will not be reachable now IIUC. > > > > Also, why explicitly check for zombies instead of having > > shrink_memcg() just skip memcgs with no zswap entries? The logic is > > slightly complicated. > > I think you have a point here, I'm not sure if the iteration can go on once we > get a zombie, if it can, we'll just skip it. If the point of skipping zombies is that we know their list_lrus are reparented, so we will end up scanning their parents again, then I believe we can just skip them. This should be "hidden" within shrink_memcg() in my opinion, with a clear comment explaining why we skip zombies. > > > > > > + if (pool->next_shrink && !mem_cgroup_online(pool->next_shrink)) { > > > + mem_cgroup_put(pool->next_shrink); > > > + pool->next_shrink = NULL; > > > + } > > > + pool->next_shrink = mem_cgroup_iter(NULL, pool->next_shrink, NULL); > > > + > > > + /* fails to find a suitable cgroup - give the worker another chance. */ > > > + if (!pool->next_shrink) { > > > + if (++memcg_selection_failures == 2) > > > + break; > > > + continue; > > > + } > > > + > > > + ret = shrink_memcg(pool->next_shrink); > > > + > > > if (ret) { > > > - zswap_reject_reclaim_fail++; > > > if (ret != -EAGAIN) > > > break; > > > if (++failures == MAX_RECLAIM_RETRIES) > > > @@ -764,9 +835,8 @@ 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); > > > INIT_WORK(&pool->shrink_work, shrink_worker); > > > + list_lru_init_memcg(&pool->list_lru, NULL); > > > > > > zswap_pool_debug("created", pool); > > > > > > @@ -831,6 +901,9 @@ 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); > > > + if (pool->next_shrink) > > > + mem_cgroup_put(pool->next_shrink); > > > for (i = 0; i < ZSWAP_NR_ZPOOLS; i++) > > > zpool_destroy_pool(pool->zpools[i]); > > > kfree(pool); > > > @@ -1199,8 +1272,10 @@ 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; > > > + int lru_alloc_ret; > > > unsigned int dlen = PAGE_SIZE; > > > unsigned long handle, value; > > > char *buf; > > > @@ -1218,14 +1293,15 @@ bool zswap_store(struct folio *folio) > > > if (!zswap_enabled || !tree) > > > return false; > > > > > > - /* > > > - * 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); > > > + if (shrink_memcg(memcg)) { > > > + mem_cgroup_put(memcg); > > > + goto reject; > > > + } > > > + mem_cgroup_put(memcg); > > > + } > > > > > > /* reclaim space if needed */ > > > if (zswap_is_full()) { > > > @@ -1240,7 +1316,11 @@ bool zswap_store(struct folio *folio) > > > else > > > zswap_pool_reached_full = false; > > > } > > > - > > > + pool = zswap_pool_current_get(); > > > + if (!pool) { > > > + ret = -EINVAL; > > > + goto reject; > > > + } > > > /* allocate entry */ > > > entry = zswap_entry_cache_alloc(GFP_KERNEL); > > > if (!entry) { > > > @@ -1256,6 +1336,7 @@ bool zswap_store(struct folio *folio) > > > entry->length = 0; > > > entry->value = value; > > > atomic_inc(&zswap_same_filled_pages); > > > + zswap_pool_put(pool); > > > goto insert_entry; > > > } > > > kunmap_atomic(src); > > > @@ -1264,6 +1345,15 @@ bool zswap_store(struct folio *folio) > > > if (!zswap_non_same_filled_pages_enabled) > > > goto freepage; > > > > > > + if (objcg) { > > > + memcg = get_mem_cgroup_from_objcg(objcg); > > > + lru_alloc_ret = memcg_list_lru_alloc(memcg, &pool->list_lru, GFP_KERNEL); > > > + mem_cgroup_put(memcg); > > > + > > > + if (lru_alloc_ret) > > > + goto freepage; > > > + } > > > + > > > /* if entry is successfully added, it keeps the reference */ > > > entry->pool = zswap_pool_current_get(); > > > if (!entry->pool) > > > @@ -1325,6 +1415,7 @@ bool zswap_store(struct folio *folio) > > > > > > insert_entry: > > > entry->objcg = objcg; > > > + entry->nid = page_to_nid(page); > > > if (objcg) { > > > obj_cgroup_charge_zswap(objcg, entry->length); > > > /* Account before objcg ref is moved to tree */ > > > @@ -1338,9 +1429,8 @@ 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(&pool->list_lru, entry); > > > } > > > spin_unlock(&tree->lock); > > > > > > @@ -1447,9 +1537,8 @@ 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); > > > @@ -1507,6 +1596,48 @@ void zswap_swapoff(int type) > > > zswap_trees[type] = NULL; > > > } > > > > > > +bool zswap_remove_swpentry_from_lru(swp_entry_t swpentry) > > > +{ > > > + struct zswap_tree *tree = zswap_trees[swp_type(swpentry)]; > > > + struct zswap_entry *entry; > > > + struct zswap_pool *pool; > > > + bool removed = false; > > > + > > > + /* get the zswap entry and prevent it from being freed */ > > > + spin_lock(&tree->lock); > > > + entry = zswap_rb_search(&tree->rbroot, swp_offset(swpentry)); > > > + /* skip if the entry is already written back or is a same filled page */ > > > + if (!entry || !entry->length) > > > + goto tree_unlock; > > > + > > > + pool = entry->pool; > > > + removed = zswap_lru_del(&pool->list_lru, entry); > > > + > > > +tree_unlock: > > > + spin_unlock(&tree->lock); > > > + return removed; > > > +} > > > + > > > +void zswap_insert_swpentry_into_lru(swp_entry_t swpentry) > > > +{ > > > + struct zswap_tree *tree = zswap_trees[swp_type(swpentry)]; > > > + struct zswap_entry *entry; > > > + struct zswap_pool *pool; > > > + > > > + /* get the zswap entry and prevent it from being freed */ > > > + spin_lock(&tree->lock); > > > + entry = zswap_rb_search(&tree->rbroot, swp_offset(swpentry)); > > > + /* skip if the entry is already written back or is a same filled page */ > > > + if (!entry || !entry->length) > > > + goto tree_unlock; > > > + > > > + pool = entry->pool; > > > + zswap_lru_add(&pool->list_lru, entry); > > > + > > > +tree_unlock: > > > + spin_unlock(&tree->lock); > > > +} > > > + > > > /********************************* > > > * debugfs functions > > > **********************************/ > > > @@ -1560,7 +1691,7 @@ static int zswap_setup(void) > > > struct zswap_pool *pool; > > > int ret; > > > > > > - zswap_entry_cache = KMEM_CACHE(zswap_entry, 0); > > > + zswap_entry_cache = KMEM_CACHE(zswap_entry, SLAB_ACCOUNT); > > > if (!zswap_entry_cache) { > > > pr_err("entry cache creation failed\n"); > > > goto cache_fail; > > > -- > > > 2.34.1
