From patchwork Fri Jun 1 00:18:34 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 10442157 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 637DE603D7 for ; Fri, 1 Jun 2018 00:18:43 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4A20F28E28 for ; Fri, 1 Jun 2018 00:18:43 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 3EEF428E2E; Fri, 1 Jun 2018 00:18:43 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=2.0 tests=BAYES_00, MAILING_LIST_MULTI, RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2B22B28E28 for ; Fri, 1 Jun 2018 00:18:42 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id BC4E86B0005; Thu, 31 May 2018 20:18:40 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id B731D6B0006; Thu, 31 May 2018 20:18:40 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A89236B0007; Thu, 31 May 2018 20:18:40 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from mail-pf0-f199.google.com (mail-pf0-f199.google.com [209.85.192.199]) by kanga.kvack.org (Postfix) with ESMTP id 5EB5C6B0005 for ; Thu, 31 May 2018 20:18:40 -0400 (EDT) Received: by mail-pf0-f199.google.com with SMTP id c4-v6so13487955pfg.22 for ; Thu, 31 May 2018 17:18:40 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-original-authentication-results:x-gm-message-state:date:from:to :cc:subject:message-id:in-reply-to:references:mime-version :content-transfer-encoding; bh=nZqqYAVvuPpio3ZcLTr8IMJJyu31PDnAMcxVMV+AxHg=; b=begjZ2tY0Sj5nw4ybUJU8w5dNlo97ZYmCeU28cA5nlvne0D/w5VV+cx8UMQbhKP5gi y7V1lUISwKLpJozDcUb8Z6CrxFtXL+7l1rvMWPx2BPxGg1C0eE59Vj9ZP8KJXw0ScSEM +uYR6oAOMzZPOViQeBQJFkbXCk2xozz9bUEa23xT+pRnQMcPZGqOIKex2J8Jt59des5q DkhM6of+wRmDfmOouGE8a56lI+61BEB/OT9A7XpNdxUJmbMNSsXO1RePmZeBIt10ZCJb dG5pADh8GQjZ7BgzhIbBZREm5vb8GznH5Gz7s3k1jEJDRQlZMEurQIV32oOPkW/KnoQ7 Y7xw== X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of akpm@linux-foundation.org designates 140.211.169.12 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-Gm-Message-State: ALKqPwecl/9ezU0eQ55QrleZjZwjRlPU7hEwv93H+xxyODCLkKBs9Bv8 KEczKSILOKBXhLnFiBO/ZR/6meMvWtJO0DaHROyyw9WiW2kPkNlUSu2ijyFCY3+2O1aNBUQDn4o p2OWPkuB3JCh8keVDK7FLr3ghPzTogCKbjFGR4miV+HssA/a7eSJdTydXNs16OcnQAQ== X-Received: by 2002:a17:902:7c83:: with SMTP id y3-v6mr8917870pll.51.1527812320001; Thu, 31 May 2018 17:18:40 -0700 (PDT) X-Google-Smtp-Source: ADUXVKIiZiSkAFcKMsxqH5eV1E3HcloFm2LHwZ0vOg3AIiCrLwn51jnUgNMi30i0sCf0WvU7F7KP X-Received: by 2002:a17:902:7c83:: with SMTP id y3-v6mr8917800pll.51.1527812318219; Thu, 31 May 2018 17:18:38 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1527812318; cv=none; d=google.com; s=arc-20160816; b=QJ0oo1f8tm26eHxkJ0+xf+9mhPAwodEXLysrU+KAq9KPFVpBmKIFEKzTsL3JDWdGz5 twrHFc0hcowW3WLQlT/FBUbHAtgfITVwpQHbsQurWP22+wcDKIjJ07NlMpTFbnPOyTWO 5yahOYzU77AY9yKdPiPSNSuW/OXPaLQ5nb+L03zTI1GVAen8GJYBarr/4Am5BgLL8PiF ctvaxy8Icb4nnRVYkNjEvbimG1m4jC/tcPZGNj2F3EQ5tEEJkLNrQeXePkf0+5qS2PRJ neIpTM0dwNoHfOe/h73E2ehHqykqc7DAOBmxG4g1ZBLEminDoBAX4Kb8ys8S8Wuu/EC1 2n8g== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:arc-authentication-results; bh=nZqqYAVvuPpio3ZcLTr8IMJJyu31PDnAMcxVMV+AxHg=; b=UruZAXqjseVlf7YB9Pv3u1E+7zss3wkKvwzB+YHxCwnLuuoPOAtaTzpoTolryJ3eHR 7CPb9ZlzoV+d+6nYmhFY2pwZzrGyr7Wm4bPHk4E/Az3sF9dF+hjgH0WauHq+IA38rKmt 0rmd7TzujH1KhnDCBMUIjiiAWO2Ms9EYvR0e0pxN/VMkKYpY2CGk70XMPxkTlJCeInjt dWpGh1g8TTYqJziiD2jZsZFqmpppW2s7eeqzytGZO44FDb4yJbUeN1rRf9ufl6uPCu/b Bggoek9xgfRm9Toc6r8wGw0Oo6kzvq1lbqjEVxRSTyFAqQdhQaA8Qte6kFvLZqIP3PZC 0Dnw== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of akpm@linux-foundation.org designates 140.211.169.12 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id e5-v6si6724014pgp.105.2018.05.31.17.18.38 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 31 May 2018 17:18:38 -0700 (PDT) Received-SPF: pass (google.com: domain of akpm@linux-foundation.org designates 140.211.169.12 as permitted sender) client-ip=140.211.169.12; Authentication-Results: mx.google.com; spf=pass (google.com: domain of akpm@linux-foundation.org designates 140.211.169.12 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org Received: from akpm3.svl.corp.google.com (unknown [104.133.9.92]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 7FA4AE17; Fri, 1 Jun 2018 00:18:37 +0000 (UTC) Date: Thu, 31 May 2018 17:18:34 -0700 From: Andrew Morton To: Shakeel Butt Cc: Michal Hocko , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Greg Thelen , Johannes Weiner , Vladimir Davydov , Tejun Heo , Linux MM , Cgroups , LKML Subject: Re: [PATCH v3] mm: fix race between kmem_cache destroy, create and deactivate Message-Id: <20180531171834.e16fc59550d24437a12c612b@linux-foundation.org> In-Reply-To: <20180530001204.183758-1-shakeelb@google.com> References: <20180530001204.183758-1-shakeelb@google.com> X-Mailer: Sylpheed 3.6.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 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: X-Virus-Scanned: ClamAV using ClamSMTP On Tue, 29 May 2018 17:12:04 -0700 Shakeel Butt wrote: > The memcg kmem cache creation and deactivation (SLUB only) is > asynchronous. If a root kmem cache is destroyed whose memcg cache is in > the process of creation or deactivation, the kernel may crash. > > Example of one such crash: > general protection fault: 0000 [#1] SMP PTI > CPU: 1 PID: 1721 Comm: kworker/14:1 Not tainted 4.17.0-smp > ... > Workqueue: memcg_kmem_cache kmemcg_deactivate_workfn > RIP: 0010:has_cpu_slab > ... > Call Trace: > ? on_each_cpu_cond > __kmem_cache_shrink > kmemcg_cache_deact_after_rcu > kmemcg_deactivate_workfn > process_one_work > worker_thread > kthread > ret_from_fork+0x35/0x40 > > To fix this race, on root kmem cache destruction, mark the cache as > dying and flush the workqueue used for memcg kmem cache creation and > deactivation. > > Signed-off-by: Shakeel Butt > --- > Changelog since v2: > - Instead of refcount, flush the workqueue This one-liner doesn't appear to fully describe the difference between v2 and v3, which is rather large: include/linux/slab.h | 3 include/linux/slab_def.h | 5 - include/linux/slub_def.h | 3 mm/memcontrol.c | 7 - mm/slab.c | 4 - mm/slab.h | 6 - mm/slab_common.c | 139 ++++++++++--------------------------- mm/slub.c | 14 +-- 8 files changed, 51 insertions(+), 130 deletions(-) diff -puN include/linux/slab_def.h~mm-fix-race-between-kmem_cache-destroy-create-and-deactivate-v3 include/linux/slab_def.h --- a/include/linux/slab_def.h~mm-fix-race-between-kmem_cache-destroy-create-and-deactivate-v3 +++ a/include/linux/slab_def.h @@ -41,10 +41,7 @@ struct kmem_cache { /* 4) cache creation/removal */ const char *name; struct list_head list; - /* Refcount for root kmem caches */ - refcount_t refcount; - /* Number of root kmem caches sharing this cache */ - int shared_count; + int refcount; int object_size; int align; diff -puN include/linux/slab.h~mm-fix-race-between-kmem_cache-destroy-create-and-deactivate-v3 include/linux/slab.h --- a/include/linux/slab.h~mm-fix-race-between-kmem_cache-destroy-create-and-deactivate-v3 +++ a/include/linux/slab.h @@ -599,6 +599,7 @@ struct memcg_cache_params { struct memcg_cache_array __rcu *memcg_caches; struct list_head __root_caches_node; struct list_head children; + bool dying; }; struct { struct mem_cgroup *memcg; @@ -615,8 +616,6 @@ struct memcg_cache_params { }; int memcg_update_all_caches(int num_memcgs); -bool kmem_cache_tryget(struct kmem_cache *s); -void kmem_cache_put(struct kmem_cache *s); /** * kmalloc_array - allocate memory for an array. diff -puN include/linux/slub_def.h~mm-fix-race-between-kmem_cache-destroy-create-and-deactivate-v3 include/linux/slub_def.h --- a/include/linux/slub_def.h~mm-fix-race-between-kmem_cache-destroy-create-and-deactivate-v3 +++ a/include/linux/slub_def.h @@ -97,8 +97,7 @@ struct kmem_cache { struct kmem_cache_order_objects max; struct kmem_cache_order_objects min; gfp_t allocflags; /* gfp flags to use on each alloc */ - refcount_t refcount; /* Refcount for root kmem cache */ - int shared_count; /* Number of kmem caches sharing this cache */ + int refcount; /* Refcount for slab cache destroy */ void (*ctor)(void *); unsigned int inuse; /* Offset to metadata */ unsigned int align; /* Alignment */ diff -puN mm/memcontrol.c~mm-fix-race-between-kmem_cache-destroy-create-and-deactivate-v3 mm/memcontrol.c --- a/mm/memcontrol.c~mm-fix-race-between-kmem_cache-destroy-create-and-deactivate-v3 +++ a/mm/memcontrol.c @@ -2181,7 +2181,6 @@ static void memcg_kmem_cache_create_func memcg_create_kmem_cache(memcg, cachep); css_put(&memcg->css); - kmem_cache_put(cachep); kfree(cw); } @@ -2197,12 +2196,6 @@ static void __memcg_schedule_kmem_cache_ if (!cw) return; - /* Make sure root kmem cache does not get destroyed in the middle */ - if (!kmem_cache_tryget(cachep)) { - kfree(cw); - return; - } - css_get(&memcg->css); cw->memcg = memcg; diff -puN mm/slab.c~mm-fix-race-between-kmem_cache-destroy-create-and-deactivate-v3 mm/slab.c --- a/mm/slab.c~mm-fix-race-between-kmem_cache-destroy-create-and-deactivate-v3 +++ a/mm/slab.c @@ -1883,8 +1883,8 @@ __kmem_cache_alias(const char *name, uns struct kmem_cache *cachep; cachep = find_mergeable(size, align, flags, name, ctor); - if (cachep && kmem_cache_tryget(cachep)) { - cachep->shared_count++; + if (cachep) { + cachep->refcount++; /* * Adjust the object sizes so that we clear diff -puN mm/slab_common.c~mm-fix-race-between-kmem_cache-destroy-create-and-deactivate-v3 mm/slab_common.c --- a/mm/slab_common.c~mm-fix-race-between-kmem_cache-destroy-create-and-deactivate-v3 +++ a/mm/slab_common.c @@ -136,6 +136,7 @@ void slab_init_memcg_params(struct kmem_ s->memcg_params.root_cache = NULL; RCU_INIT_POINTER(s->memcg_params.memcg_caches, NULL); INIT_LIST_HEAD(&s->memcg_params.children); + s->memcg_params.dying = false; } static int init_memcg_params(struct kmem_cache *s, @@ -306,7 +307,7 @@ int slab_unmergeable(struct kmem_cache * /* * We may have set a slab to be unmergeable during bootstrap. */ - if (s->shared_count < 0) + if (s->refcount < 0) return 1; return 0; @@ -391,8 +392,7 @@ static struct kmem_cache *create_cache(c if (err) goto out_free_cache; - s->shared_count = 1; - refcount_set(&s->refcount, 1); + s->refcount = 1; list_add(&s->list, &slab_caches); memcg_link_cache(s); out: @@ -609,19 +609,7 @@ void memcg_create_kmem_cache(struct mem_ * The memory cgroup could have been offlined while the cache * creation work was pending. */ - if (memcg->kmem_state != KMEM_ONLINE) - goto out_unlock; - - /* - * The root cache has been requested to be destroyed while its memcg - * cache was in creation queue. - * - * The shared_count can be out-dated or can be incremented after return. - * No big worries, at worst the creation of memcg kmem_cache is delayed. - * The next allocation will again trigger the memcg kmem_cache creation - * request. - */ - if (!root_cache->shared_count) + if (memcg->kmem_state != KMEM_ONLINE || root_cache->memcg_params.dying) goto out_unlock; idx = memcg_cache_id(memcg); @@ -676,8 +664,6 @@ static void kmemcg_deactivate_workfn(str { struct kmem_cache *s = container_of(work, struct kmem_cache, memcg_params.deact_work); - struct kmem_cache *root = s->memcg_params.root_cache; - struct mem_cgroup *memcg = s->memcg_params.memcg; get_online_cpus(); get_online_mems(); @@ -692,8 +678,7 @@ static void kmemcg_deactivate_workfn(str put_online_cpus(); /* done, put the ref from slab_deactivate_memcg_cache_rcu_sched() */ - css_put(&memcg->css); - kmem_cache_put(root); + css_put(&s->memcg_params.memcg->css); } static void kmemcg_deactivate_rcufn(struct rcu_head *head) @@ -728,8 +713,7 @@ void slab_deactivate_memcg_cache_rcu_sch WARN_ON_ONCE(s->memcg_params.deact_fn)) return; - /* Make sure root kmem_cache does not get destroyed in the middle */ - if (!kmem_cache_tryget(s->memcg_params.root_cache)) + if (s->memcg_params.root_cache->memcg_params.dying) return; /* pin memcg so that @s doesn't get destroyed in the middle */ @@ -843,11 +827,24 @@ static int shutdown_memcg_caches(struct return -EBUSY; return 0; } + +static void flush_memcg_workqueue(struct kmem_cache *s) +{ + mutex_lock(&slab_mutex); + s->memcg_params.dying = true; + mutex_unlock(&slab_mutex); + + flush_workqueue(memcg_kmem_cache_wq); +} #else static inline int shutdown_memcg_caches(struct kmem_cache *s) { return 0; } + +static inline void flush_memcg_workqueue(struct kmem_cache *s) +{ +} #endif /* CONFIG_MEMCG && !CONFIG_SLOB */ void slab_kmem_cache_release(struct kmem_cache *s) @@ -858,17 +855,23 @@ void slab_kmem_cache_release(struct kmem kmem_cache_free(kmem_cache, s); } -static void __kmem_cache_destroy(struct kmem_cache *s, bool lock) +void kmem_cache_destroy(struct kmem_cache *s) { int err; - if (lock) { - get_online_cpus(); - get_online_mems(); - mutex_lock(&slab_mutex); - } + if (unlikely(!s)) + return; + + flush_memcg_workqueue(s); + + get_online_cpus(); + get_online_mems(); - VM_BUG_ON(s->shared_count); + mutex_lock(&slab_mutex); + + s->refcount--; + if (s->refcount) + goto out_unlock; err = shutdown_memcg_caches(s); if (!err) @@ -879,75 +882,11 @@ static void __kmem_cache_destroy(struct s->name); dump_stack(); } +out_unlock: + mutex_unlock(&slab_mutex); - if (lock) { - mutex_unlock(&slab_mutex); - put_online_mems(); - put_online_cpus(); - } -} - -/* - * kmem_cache_tryget - Try to get a reference on a kmem_cache - * @s: target kmem_cache - * - * Obtain a reference on a kmem_cache unless it already has reached zero and is - * being released. The caller needs to ensure that kmem_cache is accessible. - * Currently only root kmem_cache supports reference counting. - */ -bool kmem_cache_tryget(struct kmem_cache *s) -{ - if (is_root_cache(s)) - return refcount_inc_not_zero(&s->refcount); - return false; -} - -/* - * kmem_cache_put - Put a reference on a kmem_cache - * @s: target kmem_cache - * - * Put a reference obtained via kmem_cache_tryget(). This function can not be - * called within slab_mutex as it can trigger a destruction of a kmem_cache - * which requires slab_mutex. - */ -void kmem_cache_put(struct kmem_cache *s) -{ - if (is_root_cache(s) && - refcount_dec_and_test(&s->refcount)) - __kmem_cache_destroy(s, true); -} - -/* - * kmem_cache_put_locked - Put a reference on a kmem_cache while holding - * slab_mutex - * @s: target kmem_cache - * - * Put a reference obtained via kmem_cache_tryget(). Use this function instead - * of kmem_cache_put if the caller has already acquired slab_mutex. - * - * At the moment this function is not exposed externally and is used by SLUB. - */ -void kmem_cache_put_locked(struct kmem_cache *s) -{ - if (is_root_cache(s) && - refcount_dec_and_test(&s->refcount)) - __kmem_cache_destroy(s, false); -} - -void kmem_cache_destroy(struct kmem_cache *s) -{ - if (unlikely(!s)) - return; - - /* - * It is safe to decrement shared_count without any lock. In - * __kmem_cache_alias the kmem_cache's refcount is elevated before - * incrementing shared_count and below the reference is dropped after - * decrementing shared_count. At worst shared_count can be outdated for - * a small window but that is tolerable. - */ - s->shared_count--; - kmem_cache_put(s); + put_online_mems(); + put_online_cpus(); } EXPORT_SYMBOL(kmem_cache_destroy); @@ -999,8 +938,7 @@ void __init create_boot_cache(struct kme panic("Creation of kmalloc slab %s size=%u failed. Reason %d\n", name, size, err); - s->shared_count = -1; /* Exempt from merging for now */ - refcount_set(&s->refcount, 1); + s->refcount = -1; /* Exempt from merging for now */ } struct kmem_cache *__init create_kmalloc_cache(const char *name, @@ -1015,8 +953,7 @@ struct kmem_cache *__init create_kmalloc create_boot_cache(s, name, size, flags, useroffset, usersize); list_add(&s->list, &slab_caches); memcg_link_cache(s); - s->shared_count = 1; - refcount_set(&s->refcount, 1); + s->refcount = 1; return s; } diff -puN mm/slab.h~mm-fix-race-between-kmem_cache-destroy-create-and-deactivate-v3 mm/slab.h --- a/mm/slab.h~mm-fix-race-between-kmem_cache-destroy-create-and-deactivate-v3 +++ a/mm/slab.h @@ -25,8 +25,7 @@ struct kmem_cache { unsigned int useroffset;/* Usercopy region offset */ unsigned int usersize; /* Usercopy region size */ const char *name; /* Slab name for sysfs */ - refcount_t refcount; /* Refcount for root kmem cache */ - int shared_count; /* Number of kmem caches sharing this cache */ + int refcount; /* Use counter */ void (*ctor)(void *); /* Called on object slot creation */ struct list_head list; /* List of all slab caches on the system */ }; @@ -204,8 +203,6 @@ ssize_t slabinfo_write(struct file *file void __kmem_cache_free_bulk(struct kmem_cache *, size_t, void **); int __kmem_cache_alloc_bulk(struct kmem_cache *, gfp_t, size_t, void **); -extern void kmem_cache_put_locked(struct kmem_cache *s); - #if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB) /* List of all root caches. */ @@ -298,6 +295,7 @@ extern void slab_init_memcg_params(struc extern void memcg_link_cache(struct kmem_cache *s); extern void slab_deactivate_memcg_cache_rcu_sched(struct kmem_cache *s, void (*deact_fn)(struct kmem_cache *)); + #else /* CONFIG_MEMCG && !CONFIG_SLOB */ /* If !memcg, all caches are root. */ diff -puN mm/slub.c~mm-fix-race-between-kmem_cache-destroy-create-and-deactivate-v3 mm/slub.c --- a/mm/slub.c~mm-fix-race-between-kmem_cache-destroy-create-and-deactivate-v3 +++ a/mm/slub.c @@ -4274,8 +4274,8 @@ __kmem_cache_alias(const char *name, uns struct kmem_cache *s, *c; s = find_mergeable(size, align, flags, name, ctor); - if (s && kmem_cache_tryget(s)) { - s->shared_count++; + if (s) { + s->refcount++; /* * Adjust the object sizes so that we clear @@ -4290,8 +4290,7 @@ __kmem_cache_alias(const char *name, uns } if (sysfs_slab_alias(s, name)) { - s->shared_count--; - kmem_cache_put_locked(s); + s->refcount--; s = NULL; } } @@ -5014,8 +5013,7 @@ SLAB_ATTR_RO(ctor); static ssize_t aliases_show(struct kmem_cache *s, char *buf) { - return sprintf(buf, "%d\n", - s->shared_count < 0 ? 0 : s->shared_count - 1); + return sprintf(buf, "%d\n", s->refcount < 0 ? 0 : s->refcount - 1); } SLAB_ATTR_RO(aliases); @@ -5168,7 +5166,7 @@ static ssize_t trace_store(struct kmem_c * as well as cause other issues like converting a mergeable * cache into an umergeable one. */ - if (s->shared_count > 1) + if (s->refcount > 1) return -EINVAL; s->flags &= ~SLAB_TRACE; @@ -5286,7 +5284,7 @@ static ssize_t failslab_show(struct kmem static ssize_t failslab_store(struct kmem_cache *s, const char *buf, size_t length) { - if (s->shared_count > 1) + if (s->refcount > 1) return -EINVAL; s->flags &= ~SLAB_FAILSLAB;