From patchwork Wed May 18 01:46:29 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Yu Zhao X-Patchwork-Id: 12853061 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 E7882C433EF for ; Wed, 18 May 2022 01:47:22 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 262318D0008; Tue, 17 May 2022 21:47:10 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 211E36B007B; Tue, 17 May 2022 21:47:10 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0B3ED8D0008; Tue, 17 May 2022 21:47:10 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id ED55B6B0078 for ; Tue, 17 May 2022 21:47:09 -0400 (EDT) Received: from smtpin23.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id C8BC1603B0 for ; Wed, 18 May 2022 01:47:09 +0000 (UTC) X-FDA: 79477175778.23.B837A76 Received: from mail-yb1-f202.google.com (mail-yb1-f202.google.com [209.85.219.202]) by imf19.hostedemail.com (Postfix) with ESMTP id F11191A0088 for ; Wed, 18 May 2022 01:46:58 +0000 (UTC) Received: by mail-yb1-f202.google.com with SMTP id b11-20020a5b008b000000b00624ea481d55so657291ybp.19 for ; Tue, 17 May 2022 18:47:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc:content-transfer-encoding; bh=NTA14FnCNnSPTudLkNszGIL3HdbMAT4nMBCkNLY5YRU=; b=dj/NUzQ7pldQ5p6qQOOz1M0rA++R2i0rkuA/pdh7gKHKfecCVVJbxlcKWafSRzT+io P2/TwGHl8GyP+Mg5hb/SV8E48PYJa7SyPhOeCh2WtveDGvIqR63kJBDvMBRon9bfxFwc cb+4Ti+w2hCv3EbKxHhCjMCuicPeQiavbDKafGr2N+HvVGBiBGlMin4TBHAZPvg5HWiV fsxaCDJXxWjs84OmU9+hKlIJ1ZEGHcKvSILfuBZ+lCwaenIW0SoaNOUqcU3H99tZA0Pp OpihneRVY05VI5/nix7QlSlUnp7oGxB689r8rUG7RiYvAjaJUxEm2rPSva5gOkSmMRqe EN5A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc:content-transfer-encoding; bh=NTA14FnCNnSPTudLkNszGIL3HdbMAT4nMBCkNLY5YRU=; b=mapcmRyMdBQmtzlaOI5i135Z416E3pK2r+/joD6FdsomKR2NIge99jEMiVBQUZ5BBK 3Labrl3DTQ05n/omijAG546BAvi+0AJMJtTyHulEIRIi66SC43rnmUKx8A1mWmUOAfVi RNx04HwHguXXTqLbi886fqdymuXKN7kd7VH92uus5M9CLzx36ryBI7GSMrm5DOYmQdgl 5HDOgS1U2EEumaOsddyou75CZhhxIuNPNlN/1T/l7NJqa+BwpE/Pf/TYzWyGLHP1fI22 Xesm2hsE30QU+uiODUdNPzCVcdtm+Dai8MKNUxlnF7IR1FmCgzSiQ90zqlMrRpiCGk38 ietw== X-Gm-Message-State: AOAM533+mnDDRXUHX3zcLQghxfwYVsIYu0Gj1qpFi44woTNUPFrj/aID 2wweEAUQW09JhrM+fjFP67zuntC9vo8= X-Google-Smtp-Source: ABdhPJwTsKX58YMZjZU473qHcm2WfVL2bwxTclJIx+w2+3BMEn4WcPcuNwyIzbAE4LxodKTFVAQMvubt74g= X-Received: from yuzhao.bld.corp.google.com ([2620:15c:183:200:f7bc:90c9:d86e:4ea8]) (user=yuzhao job=sendgmr) by 2002:a81:ac11:0:b0:2fe:ee45:c6bb with SMTP id k17-20020a81ac11000000b002feee45c6bbmr15371827ywh.427.1652838428578; Tue, 17 May 2022 18:47:08 -0700 (PDT) Date: Tue, 17 May 2022 19:46:29 -0600 In-Reply-To: <20220518014632.922072-1-yuzhao@google.com> Message-Id: <20220518014632.922072-11-yuzhao@google.com> Mime-Version: 1.0 References: <20220518014632.922072-1-yuzhao@google.com> X-Mailer: git-send-email 2.36.0.550.gb090851708-goog Subject: [PATCH v11 10/14] mm: multi-gen LRU: kill switch From: Yu Zhao To: Andrew Morton , linux-mm@kvack.org Cc: Andi Kleen , Aneesh Kumar , Catalin Marinas , Dave Hansen , Hillf Danton , Jens Axboe , Johannes Weiner , Jonathan Corbet , Linus Torvalds , Matthew Wilcox , Mel Gorman , Michael Larabel , Michal Hocko , Mike Rapoport , Peter Zijlstra , Tejun Heo , Vlastimil Babka , Will Deacon , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org, page-reclaim@google.com, Yu Zhao , Brian Geffon , Jan Alexander Steffens , Oleksandr Natalenko , Steven Barrett , Suleiman Souhlal , Daniel Byrne , Donald Carr , " =?utf-8?q?Holger_Hoffst=C3=A4tte?= " , Konstantin Kharlamov , Shuang Zhai , Sofia Trinh , Vaibhav Jain X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: F11191A0088 X-Stat-Signature: awxnbk57qeur53tocthq3a59frfze14t Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b="dj/NUzQ7"; spf=pass (imf19.hostedemail.com: domain of 3HFCEYgYKCOchdiQJXPXXPUN.LXVURWdg-VVTeJLT.XaP@flex--yuzhao.bounces.google.com designates 209.85.219.202 as permitted sender) smtp.mailfrom=3HFCEYgYKCOchdiQJXPXXPUN.LXVURWdg-VVTeJLT.XaP@flex--yuzhao.bounces.google.com; dmarc=pass (policy=reject) header.from=google.com X-HE-Tag: 1652838418-937017 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: Add /sys/kernel/mm/lru_gen/enabled as a kill switch. Components that can be disabled include: 0x0001: the multi-gen LRU core 0x0002: walking page table, when arch_has_hw_pte_young() returns true 0x0004: clearing the accessed bit in non-leaf PMD entries, when CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG=y [yYnN]: apply to all the components above E.g., echo y >/sys/kernel/mm/lru_gen/enabled cat /sys/kernel/mm/lru_gen/enabled 0x0007 echo 5 >/sys/kernel/mm/lru_gen/enabled cat /sys/kernel/mm/lru_gen/enabled 0x0005 NB: the page table walks happen on the scale of seconds under heavy memory pressure, in which case the mmap_lock contention is a lesser concern, compared with the LRU lock contention and the I/O congestion. So far the only well-known case of the mmap_lock contention happens on Android, due to Scudo [1] which allocates several thousand VMAs for merely a few hundred MBs. The SPF and the Maple Tree also have provided their own assessments [2][3]. However, if walking page tables does worsen the mmap_lock contention, the kill switch can be used to disable it. In this case the multi-gen LRU will suffer a minor performance degradation, as shown previously. Clearing the accessed bit in non-leaf PMD entries can also be disabled, since this behavior was not tested on x86 varieties other than Intel and AMD. [1] https://source.android.com/devices/tech/debug/scudo [2] https://lore.kernel.org/r/20220128131006.67712-1-michel@lespinasse.org/ [3] https://lore.kernel.org/r/20220426150616.3937571-1-Liam.Howlett@oracle.com/ Signed-off-by: Yu Zhao Acked-by: Brian Geffon Acked-by: Jan Alexander Steffens (heftig) Acked-by: Oleksandr Natalenko Acked-by: Steven Barrett Acked-by: Suleiman Souhlal Tested-by: Daniel Byrne Tested-by: Donald Carr Tested-by: Holger Hoffstätte Tested-by: Konstantin Kharlamov Tested-by: Shuang Zhai Tested-by: Sofia Trinh Tested-by: Vaibhav Jain --- include/linux/cgroup.h | 15 +- include/linux/mm_inline.h | 12 +- include/linux/mmzone.h | 9 ++ kernel/cgroup/cgroup-internal.h | 1 - mm/Kconfig | 6 + mm/vmscan.c | 238 +++++++++++++++++++++++++++++++- 6 files changed, 272 insertions(+), 9 deletions(-) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 0d1ada8968d7..1bc0cabf993f 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -432,6 +432,18 @@ static inline void cgroup_put(struct cgroup *cgrp) css_put(&cgrp->self); } +extern struct mutex cgroup_mutex; + +static inline void cgroup_lock(void) +{ + mutex_lock(&cgroup_mutex); +} + +static inline void cgroup_unlock(void) +{ + mutex_unlock(&cgroup_mutex); +} + /** * task_css_set_check - obtain a task's css_set with extra access conditions * @task: the task to obtain css_set for @@ -446,7 +458,6 @@ static inline void cgroup_put(struct cgroup *cgrp) * as locks used during the cgroup_subsys::attach() methods. */ #ifdef CONFIG_PROVE_RCU -extern struct mutex cgroup_mutex; extern spinlock_t css_set_lock; #define task_css_set_check(task, __c) \ rcu_dereference_check((task)->cgroups, \ @@ -708,6 +719,8 @@ struct cgroup; static inline u64 cgroup_id(const struct cgroup *cgrp) { return 1; } static inline void css_get(struct cgroup_subsys_state *css) {} static inline void css_put(struct cgroup_subsys_state *css) {} +static inline void cgroup_lock(void) {} +static inline void cgroup_unlock(void) {} static inline int cgroup_attach_task_all(struct task_struct *from, struct task_struct *t) { return 0; } static inline int cgroupstats_build(struct cgroupstats *stats, diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h index 85fe78832436..d3d7b7bb297d 100644 --- a/include/linux/mm_inline.h +++ b/include/linux/mm_inline.h @@ -106,7 +106,15 @@ static __always_inline enum lru_list folio_lru_list(struct folio *folio) static inline bool lru_gen_enabled(void) { - return true; +#ifdef CONFIG_LRU_GEN_ENABLED + DECLARE_STATIC_KEY_TRUE(lru_gen_caps[NR_LRU_GEN_CAPS]); + + return static_branch_likely(&lru_gen_caps[LRU_GEN_CORE]); +#else + DECLARE_STATIC_KEY_FALSE(lru_gen_caps[NR_LRU_GEN_CAPS]); + + return static_branch_unlikely(&lru_gen_caps[LRU_GEN_CORE]); +#endif } static inline bool lru_gen_in_fault(void) @@ -219,7 +227,7 @@ static inline bool lru_gen_add_folio(struct lruvec *lruvec, struct folio *folio, VM_WARN_ON_ONCE_FOLIO(gen != -1, folio); - if (folio_test_unevictable(folio)) + if (folio_test_unevictable(folio) || !lrugen->enabled) return false; /* * There are three common cases for this page: diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 6aa715a2fea1..372a7f5a6829 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -386,6 +386,13 @@ enum { LRU_GEN_FILE, }; +enum { + LRU_GEN_CORE, + LRU_GEN_MM_WALK, + LRU_GEN_NONLEAF_YOUNG, + NR_LRU_GEN_CAPS +}; + #define MIN_LRU_BATCH BITS_PER_LONG #define MAX_LRU_BATCH (MIN_LRU_BATCH * 128) @@ -427,6 +434,8 @@ struct lru_gen_struct { /* can be modified without holding the LRU lock */ atomic_long_t evicted[NR_HIST_GENS][ANON_AND_FILE][MAX_NR_TIERS]; atomic_long_t refaulted[NR_HIST_GENS][ANON_AND_FILE][MAX_NR_TIERS]; + /* whether the multi-gen LRU is enabled */ + bool enabled; }; enum { diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h index 6e36e854b512..929ed3bf1a7c 100644 --- a/kernel/cgroup/cgroup-internal.h +++ b/kernel/cgroup/cgroup-internal.h @@ -165,7 +165,6 @@ struct cgroup_mgctx { #define DEFINE_CGROUP_MGCTX(name) \ struct cgroup_mgctx name = CGROUP_MGCTX_INIT(name) -extern struct mutex cgroup_mutex; extern spinlock_t css_set_lock; extern struct cgroup_subsys *cgroup_subsys[]; extern struct list_head cgroup_roots; diff --git a/mm/Kconfig b/mm/Kconfig index 0aeacbd3361c..426ea5f57d88 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -918,6 +918,12 @@ config LRU_GEN help A high performance LRU implementation to overcommit memory. +config LRU_GEN_ENABLED + bool "Enable by default" + depends on LRU_GEN + help + This option enables the multi-gen LRU by default. + config LRU_GEN_STATS bool "Full stats for debugging" depends on LRU_GEN diff --git a/mm/vmscan.c b/mm/vmscan.c index a7e768675707..09e2c3e6f2be 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -52,6 +52,7 @@ #include #include #include +#include #include #include @@ -2989,6 +2990,12 @@ static bool can_age_anon_pages(struct pglist_data *pgdat, #ifdef CONFIG_LRU_GEN +#ifdef CONFIG_LRU_GEN_ENABLED +DEFINE_STATIC_KEY_ARRAY_TRUE(lru_gen_caps, NR_LRU_GEN_CAPS); +#else +DEFINE_STATIC_KEY_ARRAY_FALSE(lru_gen_caps, NR_LRU_GEN_CAPS); +#endif + /****************************************************************************** * shorthand helpers ******************************************************************************/ @@ -3009,6 +3016,15 @@ static bool can_age_anon_pages(struct pglist_data *pgdat, for ((type) = 0; (type) < ANON_AND_FILE; (type)++) \ for ((zone) = 0; (zone) < MAX_NR_ZONES; (zone)++) +static bool get_cap(int cap) +{ +#ifdef CONFIG_LRU_GEN_ENABLED + return static_branch_likely(&lru_gen_caps[cap]); +#else + return static_branch_unlikely(&lru_gen_caps[cap]); +#endif +} + static struct lruvec *get_lruvec(struct mem_cgroup *memcg, int nid) { struct pglist_data *pgdat = NODE_DATA(nid); @@ -3816,7 +3832,8 @@ static void walk_pmd_range_locked(pud_t *pud, unsigned long next, struct vm_area goto next; if (!pmd_trans_huge(pmd[i])) { - if (IS_ENABLED(CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG)) + if (IS_ENABLED(CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG) && + get_cap(LRU_GEN_NONLEAF_YOUNG)) pmdp_test_and_clear_young(vma, addr, pmd + i); goto next; } @@ -3926,10 +3943,12 @@ static void walk_pmd_range(pud_t *pud, unsigned long start, unsigned long end, walk->mm_stats[MM_PMD_TOTAL]++; #ifdef CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG - if (!pmd_young(val)) - continue; + if (get_cap(LRU_GEN_NONLEAF_YOUNG)) { + if (!pmd_young(val)) + continue; - walk_pmd_range_locked(pud, addr, vma, args, &pos); + walk_pmd_range_locked(pud, addr, vma, args, &pos); + } #endif if (!walk->force_scan && !test_bloom_filter(walk->lruvec, walk->max_seq, pmd + i)) continue; @@ -4162,7 +4181,7 @@ static bool try_to_inc_max_seq(struct lruvec *lruvec, unsigned long max_seq, * handful of PTEs. Spreading the work out over a period of time usually * is less efficient, but it avoids bursty page faults. */ - if (!arch_has_hw_pte_young()) { + if (!(arch_has_hw_pte_young() && get_cap(LRU_GEN_MM_WALK))) { success = iterate_mm_list_nowalk(lruvec, max_seq); goto done; } @@ -4895,6 +4914,211 @@ static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc blk_finish_plug(&plug); } +/****************************************************************************** + * state change + ******************************************************************************/ + +static bool __maybe_unused state_is_valid(struct lruvec *lruvec) +{ + struct lru_gen_struct *lrugen = &lruvec->lrugen; + + if (lrugen->enabled) { + enum lru_list lru; + + for_each_evictable_lru(lru) { + if (!list_empty(&lruvec->lists[lru])) + return false; + } + } else { + int gen, type, zone; + + for_each_gen_type_zone(gen, type, zone) { + if (!list_empty(&lrugen->lists[gen][type][zone])) + return false; + + /* unlikely but not a bug when reset_batch_size() is pending */ + VM_WARN_ON_ONCE(lrugen->nr_pages[gen][type][zone]); + } + } + + return true; +} + +static bool fill_evictable(struct lruvec *lruvec) +{ + enum lru_list lru; + int remaining = MAX_LRU_BATCH; + + for_each_evictable_lru(lru) { + int type = is_file_lru(lru); + bool active = is_active_lru(lru); + struct list_head *head = &lruvec->lists[lru]; + + while (!list_empty(head)) { + bool success; + struct folio *folio = lru_to_folio(head); + + VM_WARN_ON_ONCE_FOLIO(folio_test_unevictable(folio), folio); + VM_WARN_ON_ONCE_FOLIO(folio_test_active(folio) != active, folio); + VM_WARN_ON_ONCE_FOLIO(folio_is_file_lru(folio) != type, folio); + VM_WARN_ON_ONCE_FOLIO(folio_lru_gen(folio) != -1, folio); + + lruvec_del_folio(lruvec, folio); + success = lru_gen_add_folio(lruvec, folio, false); + VM_WARN_ON_ONCE(!success); + + if (!--remaining) + return false; + } + } + + return true; +} + +static bool drain_evictable(struct lruvec *lruvec) +{ + int gen, type, zone; + int remaining = MAX_LRU_BATCH; + + for_each_gen_type_zone(gen, type, zone) { + struct list_head *head = &lruvec->lrugen.lists[gen][type][zone]; + + while (!list_empty(head)) { + bool success; + struct folio *folio = lru_to_folio(head); + + VM_WARN_ON_ONCE_FOLIO(folio_test_unevictable(folio), folio); + VM_WARN_ON_ONCE_FOLIO(folio_test_active(folio), folio); + VM_WARN_ON_ONCE_FOLIO(folio_is_file_lru(folio) != type, folio); + VM_WARN_ON_ONCE_FOLIO(folio_zonenum(folio) != zone, folio); + + success = lru_gen_del_folio(lruvec, folio, false); + VM_WARN_ON_ONCE(!success); + lruvec_add_folio(lruvec, folio); + + if (!--remaining) + return false; + } + } + + return true; +} + +static void lru_gen_change_state(bool enable) +{ + static DEFINE_MUTEX(state_mutex); + + struct mem_cgroup *memcg; + + cgroup_lock(); + cpus_read_lock(); + get_online_mems(); + mutex_lock(&state_mutex); + + if (enable == lru_gen_enabled()) + goto unlock; + + if (enable) + static_branch_enable_cpuslocked(&lru_gen_caps[LRU_GEN_CORE]); + else + static_branch_disable_cpuslocked(&lru_gen_caps[LRU_GEN_CORE]); + + memcg = mem_cgroup_iter(NULL, NULL, NULL); + do { + int nid; + + for_each_node(nid) { + struct lruvec *lruvec = get_lruvec(memcg, nid); + + if (!lruvec) + continue; + + spin_lock_irq(&lruvec->lru_lock); + + VM_WARN_ON_ONCE(!seq_is_valid(lruvec)); + VM_WARN_ON_ONCE(!state_is_valid(lruvec)); + + lruvec->lrugen.enabled = enable; + + while (!(enable ? fill_evictable(lruvec) : drain_evictable(lruvec))) { + spin_unlock_irq(&lruvec->lru_lock); + cond_resched(); + spin_lock_irq(&lruvec->lru_lock); + } + + spin_unlock_irq(&lruvec->lru_lock); + } + + cond_resched(); + } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL))); +unlock: + mutex_unlock(&state_mutex); + put_online_mems(); + cpus_read_unlock(); + cgroup_unlock(); +} + +/****************************************************************************** + * sysfs interface + ******************************************************************************/ + +static ssize_t show_enable(struct kobject *kobj, struct kobj_attribute *attr, char *buf) +{ + unsigned int caps = 0; + + if (get_cap(LRU_GEN_CORE)) + caps |= BIT(LRU_GEN_CORE); + + if (arch_has_hw_pte_young() && get_cap(LRU_GEN_MM_WALK)) + caps |= BIT(LRU_GEN_MM_WALK); + + if (IS_ENABLED(CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG) && get_cap(LRU_GEN_NONLEAF_YOUNG)) + caps |= BIT(LRU_GEN_NONLEAF_YOUNG); + + return snprintf(buf, PAGE_SIZE, "0x%04x\n", caps); +} + +static ssize_t store_enable(struct kobject *kobj, struct kobj_attribute *attr, + const char *buf, size_t len) +{ + int i; + unsigned int caps; + + if (tolower(*buf) == 'n') + caps = 0; + else if (tolower(*buf) == 'y') + caps = -1; + else if (kstrtouint(buf, 0, &caps)) + return -EINVAL; + + for (i = 0; i < NR_LRU_GEN_CAPS; i++) { + bool enable = caps & BIT(i); + + if (i == LRU_GEN_CORE) + lru_gen_change_state(enable); + else if (enable) + static_branch_enable(&lru_gen_caps[i]); + else + static_branch_disable(&lru_gen_caps[i]); + } + + return len; +} + +static struct kobj_attribute lru_gen_enabled_attr = __ATTR( + enabled, 0644, show_enable, store_enable +); + +static struct attribute *lru_gen_attrs[] = { + &lru_gen_enabled_attr.attr, + NULL +}; + +static struct attribute_group lru_gen_attr_group = { + .name = "lru_gen", + .attrs = lru_gen_attrs, +}; + /****************************************************************************** * initialization ******************************************************************************/ @@ -4905,6 +5129,7 @@ void lru_gen_init_lruvec(struct lruvec *lruvec) struct lru_gen_struct *lrugen = &lruvec->lrugen; lrugen->max_seq = MIN_NR_GENS + 1; + lrugen->enabled = lru_gen_enabled(); for_each_gen_type_zone(gen, type, zone) INIT_LIST_HEAD(&lrugen->lists[gen][type][zone]); @@ -4945,6 +5170,9 @@ static int __init init_lru_gen(void) BUILD_BUG_ON(BIT(LRU_GEN_WIDTH) <= MAX_NR_GENS); BUILD_BUG_ON(sizeof(MM_STAT_CODES) != NR_MM_STATS + 1); + if (sysfs_create_group(mm_kobj, &lru_gen_attr_group)) + pr_err("lru_gen: failed to create sysfs group\n"); + return 0; }; late_initcall(init_lru_gen);