From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id DA542C10F07 for ; Tue, 5 Dec 2023 18:21:15 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3E00D6B007B; Tue, 5 Dec 2023 13:21:15 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 38F3A6B007E; Tue, 5 Dec 2023 13:21:15 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 22F386B0081; Tue, 5 Dec 2023 13:21:15 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 0CF106B007B for ; Tue, 5 Dec 2023 13:21:15 -0500 (EST) Received: from smtpin28.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id DBF00A0B55 for ; Tue, 5 Dec 2023 18:21:14 +0000 (UTC) X-FDA: 81533581668.28.8EF0AA7 Received: from mail-ej1-f41.google.com (mail-ej1-f41.google.com [209.85.218.41]) by imf11.hostedemail.com (Postfix) with ESMTP id 03CF640018 for ; Tue, 5 Dec 2023 18:21:12 +0000 (UTC) Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=google.com header.s=20230601 header.b=POWHuMnv; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf11.hostedemail.com: domain of yosryahmed@google.com designates 209.85.218.41 as permitted sender) smtp.mailfrom=yosryahmed@google.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1701800473; a=rsa-sha256; cv=none; b=23K463tzJC/badklRGxEmpe9ufBBer5t5PS7qsArSzXWK8Xaaz3DLfEe+ehnc2hHuuZX/+ QbF3htk82P2+ltuiKvm2TzX00CmXHK6GNjrYYO21BGIkRquLutq1tkLr1TOaTzCrWt79WO C5ngF0/oSjE4M8OgHXn8c7tTyTrYeZ4= ARC-Authentication-Results: i=1; imf11.hostedemail.com; dkim=pass header.d=google.com header.s=20230601 header.b=POWHuMnv; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf11.hostedemail.com: domain of yosryahmed@google.com designates 209.85.218.41 as permitted sender) smtp.mailfrom=yosryahmed@google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1701800473; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=6WN4u2moZSshqPu3Y/V5gB+4V90bfYqpJZl++tq0u6Q=; b=t7TUGcA8Yr7MQfhgp5MVJtM7WwLdagmsN4g7sTCHdnBca5BU1xTtnNunt2Few47GfbcfZI zxFSnP3dyghg6DvOnMRYr5KIjr+1llqbHuA7CkcpHl7aj07I4l3zNBezB62EAKfJeAAF4S fHg4HABI3pfpwoxG1bgYNpRniAvu1gs= Received: by mail-ej1-f41.google.com with SMTP id a640c23a62f3a-a1b6b65923eso358483266b.3 for ; Tue, 05 Dec 2023 10:21:12 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1701800471; x=1702405271; darn=kvack.org; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=6WN4u2moZSshqPu3Y/V5gB+4V90bfYqpJZl++tq0u6Q=; b=POWHuMnvWUcYVNYvk4vOcvBA23QV6WzxwjFK5xfRHwXvrAhh6LGlOrZ0/3NXGXmDrU H2jGLnseI0DYhT8WnM+kJP+hSXPpweMnR/ai4hmOkQuQn1WRW/OW0Y4vEdjgQjibWJ8x kdriI7kW/iNSPe2Q8ESzN0vzaHXpJm5oBtXwAf/XiQdEm8Mp0ynaAt0bY2QzLIsbtas9 U7lwIOP8NlWpoFh3aG3Pzv5d2b1QiIuCnG1XC2vqYu1GgCHR/UImIzo7fo61csItZ1Cg l2TGf4ymzin4vNf9H7yKOVnpc4/1+aP8zLq4ldiMx5X91jM/uA/0f5gDSNiFXsGkAHJx rIow== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1701800471; x=1702405271; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=6WN4u2moZSshqPu3Y/V5gB+4V90bfYqpJZl++tq0u6Q=; b=STQKj7vOzSFsZfB3+0+X72b8MUK6ABaE3WGxKVMN0Gnbg/xBqaDLwVRGh8otVy/fa4 /duAs9RMQIZOJvWeSmpNUxBoacSUAJrMGTgBHaGEFc3hPcEuylimr7xDxR9fM4h9/15P 6o71jUyudjIOo9ULAnYbwr34GHxZJkH2AXvo71iusG8k1wYaj/1NocQmrjpE0oxoOxTv 9k997xmHdO4L8FE3Xs8+z4QHdJ3ZGRHIqI1aL2LjosqgwBTiqBA2G9+01JvuHsmQ9kIe 86eYDLhpSclW34Sw9Ulv/UfGeXj/aqrLh0kSupuVC0MXF4eZfUP3O0ySknBxOlNf6qHb VTiQ== X-Gm-Message-State: AOJu0YzTsTlJw6b8F+G3z8qyGX5qJMZgMKLlPugb1kaxHUASlgOkq1uU o635FyC+6v8GSnROv2520QyuR27YOB8YevbKkvKBcQ== X-Google-Smtp-Source: AGHT+IGd1yg6PQF7ayoTAJjFfhVuGb0UGlI5hkzGDUocfT7xoFuP7JHAGnIA07SDpR1nyiOYEVf8Yw/JuOkWcUUZlLY= X-Received: by 2002:a17:906:7f85:b0:a19:a19b:421d with SMTP id f5-20020a1709067f8500b00a19a19b421dmr581665ejr.136.1701800471333; Tue, 05 Dec 2023 10:21:11 -0800 (PST) MIME-Version: 1.0 References: <20231130194023.4102148-1-nphamcs@gmail.com> <20231130194023.4102148-4-nphamcs@gmail.com> In-Reply-To: <20231130194023.4102148-4-nphamcs@gmail.com> From: Yosry Ahmed Date: Tue, 5 Dec 2023 10:20:35 -0800 Message-ID: Subject: Re: [PATCH v8 3/6] zswap: make shrinking memcg-aware To: Nhat Pham Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, cerasuolodomenico@gmail.com, sjenning@redhat.com, ddstreet@ieee.org, vitaly.wool@konsulko.com, mhocko@kernel.org, roman.gushchin@linux.dev, shakeelb@google.com, muchun.song@linux.dev, chrisl@kernel.org, linux-mm@kvack.org, kernel-team@meta.com, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, shuah@kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 03CF640018 X-Stat-Signature: 1o3gc9xsa6zpsnt73d85qhezmn3sdgd5 X-HE-Tag: 1701800472-421525 X-HE-Meta: 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 EqILjLOC i4maP386Hc7BJhhJdsp0wlc0s0axaBz1lm6srLNemO7BksLCDVEaz3TwqZwjYtxD+eCd5sPtt7pWBCU649tfnGTRf8YSiFMQEVudFAZnBjUwHSJFKI1FEeqDR/hfCUMETzhEKD8YJWEL76jJbSj8FiAuqxy5WtII+j5TrlIlPb198Uh0d5AeZFMC+oGJyDNcw8BPmV55heBqs2x0YbhVcJzoRnmxRYRhGdh8rIpe4jv7tx00bfwB9XAx64d9/6EXYq/0UxTvEEINjU3SbqlOi2yxlBoisIJC6R6fFOVjKC+zPFcz05PvwMKBY1A== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Nov 30, 2023 at 11:40=E2=80=AFAM Nhat Pham wrot= e: > > From: Domenico Cerasuolo > > 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 > Co-developed-by: Nhat Pham > Signed-off-by: Nhat Pham > --- > 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_cg= roup *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_su= bsys_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, g= fp_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 ent= ry, gfp_t gfp_mask, > if (err !=3D -EEXIST) > goto fail_put_swap; > > + /* > + * Protect against a recursive call to __read_swap_cache_= async() > + * on the same entry waiting forever here because SWAP_HA= S_CACHE > + * is set but the folio is not the swap cache yet. This c= an > + * 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 =3D get_vma_policy(vma, addr, 0, &ilx); > page =3D __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 =3D __read_swap_cache_async( > swp_entry(swp_type(entry), offset), > - gfp_mask, mpol, ilx, &page_allocated); > + gfp_mask, mpol, ilx, &page_allocated, fal= se); > 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 =3D __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 ta= rg_entry, gfp_t gfp_mask, > pte_unmap(pte); > pte =3D NULL; > page =3D __read_swap_cache_async(entry, gfp_mask, mpol, i= lx, > - &page_allocated); > + &page_allocated, false); > if (!page) > continue; > if (page_allocated) { > @@ -847,7 +859,7 @@ static struct page *swap_vma_readahead(swp_entry_t ta= rg_entry, gfp_t gfp_mask, > skip: > /* The page was likely read above, so no need for plugging here *= / > page =3D __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 > #include > #include > +#include > > #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 =3D 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_entr= y *entry) > +{ > + return entry->objcg ? obj_cgroup_memcg(entry->objcg) : NULL; > +} > +#else > +static inline struct mem_cgroup *mem_cgroup_from_entry(struct zswap_entr= y *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 =3D=3D memcg) > + pool->next_shrink =3D 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 =3D kmem_cache_alloc(zswap_entry_cache, gfp); > + entry =3D kmem_cache_alloc_node(zswap_entry_cache, gfp, nid); > if (!entry) > return NULL; > entry->refcount =3D 1; > @@ -312,6 +344,61 @@ static void zswap_entry_cache_free(struct zswap_entr= y *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 =3D 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 ind= irection > + * 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_l= ru. > + * > + * Similar reasoning holds for list_lru_del() and list_lru_putbac= k(). > + */ > + rcu_read_lock(); > + memcg =3D 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 =3D entry_to_nid(entry); > + struct mem_cgroup *memcg; > + > + rcu_read_lock(); > + memcg =3D 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 =3D entry_to_nid(entry); > + spinlock_t *lock =3D &list_lru->node[nid].lock; > + struct mem_cgroup *memcg; > + > + rcu_read_lock(); > + memcg =3D 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 *entr= y) > 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_tre= e *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 li= st_lru_one *l, > + spinlock_t *lock, void *arg) > { > - struct zswap_entry *entry; > + struct zswap_entry *entry =3D container_of(item, struct zswap_ent= ry, lru); > struct zswap_tree *tree; > pgoff_t swpoffset; > - int ret; > + enum lru_status ret =3D 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 =3D 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 agai= n > @@ -654,28 +733,32 @@ static int zswap_reclaim_entry(struct zswap_pool *p= ool) > */ > swpoffset =3D swp_offset(entry->swpentry); > tree =3D 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 !=3D zswap_rb_search(&tree->rbroot, swpoffset)) { > - ret =3D -EAGAIN; > + if (entry !=3D 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 =3D zswap_writeback_entry(entry, tree); > + writeback_result =3D 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 =3D 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 *p= ool) > 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 =3D 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 =3D zswap_pool_current_get(); > + if (!pool) > + return -EINVAL; > + > + for_each_node_state(nid, N_NORMAL_MEMORY) { > + unsigned long nr_to_walk =3D 1; > + > + shrunk +=3D list_lru_walk_one(&pool->list_lru, nid, memcg= , > + &shrink_memcg_cb, NULL, &nr_t= o_walk); > + } > + zswap_pool_put(pool); > + return shrunk ? 0 : -EAGAIN; > } > > static void shrink_worker(struct work_struct *w) > { > struct zswap_pool *pool =3D container_of(w, typeof(*pool), > shrink_work); > + struct mem_cgroup *memcg; > int ret, failures =3D 0; > > + /* global reclaim will select cgroup in a round-robin fashion. */ > do { > - ret =3D zswap_reclaim_entry(pool); > - if (ret) { > - zswap_reject_reclaim_fail++; > - if (ret !=3D -EAGAIN) > + spin_lock(&zswap_pools_lock); > + pool->next_shrink =3D mem_cgroup_iter(NULL, pool->next_sh= rink, NULL); > + memcg =3D 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 effe= ct of the > + * zswap memcg offlining cleanup callback). This is not c= atastrophic > + * per se, but it will keep the now offlined memcg hostag= e for a while. > + * > + * Note that if we got an online memcg, we will keep the = extra > + * reference in case the original reference obtained by m= em_cgroup_iter > + * is dropped by the zswap memcg offlining callback, ensu= ring that the > + * memcg is not killed when we are reclaiming. > + */ > + if (!memcg) { > + spin_unlock(&zswap_pools_lock); > + if (++failures =3D=3D 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 =3D NULL; > + spin_unlock(&zswap_pools_lock); > + > if (++failures =3D=3D MAX_RECLAIM_RETRIES) > break; > + > + goto resched; > } > + spin_unlock(&zswap_pools_lock); > + > + ret =3D 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 =3D=3D -EINVAL) > + break; > + if (ret && ++failures =3D=3D 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 *typ= e, 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 *po= ol) > > cpuhp_state_remove_instance(CPUHP_MM_ZSWP_POOL_PREPARE, &pool->no= de); > 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 =3D NULL; > + spin_unlock(&zswap_pools_lock); > + > for (i =3D 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 =3D get_task_policy(current); > page =3D __read_swap_cache_async(swpentry, GFP_KERNEL, mpol, > - NO_INTERLEAVE_INDEX, &page_was_allocated)= ; > + NO_INTERLEAVE_INDEX, &page_was_allocated,= true); > if (!page) { > ret =3D -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 =3D NULL; > + struct mem_cgroup *memcg =3D NULL; > struct zswap_pool *pool; > struct zpool *zpool; > unsigned int dlen =3D 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 b= ased on > - * local cgroup limits. > - */ > objcg =3D get_obj_cgroup_from_folio(folio); > - if (objcg && !obj_cgroup_may_zswap(objcg)) > - goto reject; > + if (objcg && !obj_cgroup_may_zswap(objcg)) { > + memcg =3D 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 =3D zswap_entry_cache_alloc(GFP_KERNEL); > + entry =3D 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 =3D get_mem_cgroup_from_objcg(objcg); > + if (memcg_list_lru_alloc(memcg, &entry->pool->list_lru, G= FP_KERNEL)) { > + mem_cgroup_put(memcg); > + goto put_pool; > + } > + mem_cgroup_put(memcg); > + } > + > /* compress */ > acomp_ctx =3D 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