From patchwork Tue Oct 10 00:09:25 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roman Gushchin X-Patchwork-Id: 13414695 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 46850E95A9C for ; Tue, 10 Oct 2023 00:10:03 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id CFD238D009D; Mon, 9 Oct 2023 20:10:02 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id CAC0A8D0089; Mon, 9 Oct 2023 20:10:02 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B27B58D009D; Mon, 9 Oct 2023 20:10:02 -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 A51B18D0089 for ; Mon, 9 Oct 2023 20:10:02 -0400 (EDT) Received: from smtpin04.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 7D660140356 for ; Tue, 10 Oct 2023 00:10:02 +0000 (UTC) X-FDA: 81327619044.04.693F27B Received: from out-206.mta0.migadu.com (out-206.mta0.migadu.com [91.218.175.206]) by imf18.hostedemail.com (Postfix) with ESMTP id CBE9A1C0004 for ; Tue, 10 Oct 2023 00:10:00 +0000 (UTC) Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=ft97nbcy; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf18.hostedemail.com: domain of roman.gushchin@linux.dev designates 91.218.175.206 as permitted sender) smtp.mailfrom=roman.gushchin@linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1696896601; a=rsa-sha256; cv=none; b=Vu8wlI2d+qFGiz6926PbNUKAfkISexD6EDYfSWJUlo/h1zsD5Kx8iReT6KmpyRDREnNoWX qcsSYI6MNrlpDVi/H4G9X8bbfQEJlmKYtR+5AB5b4pVqsla1X03MEo/sHUcCVKKoIBnDuq mGrWTWrSnmVV7fazHb1wDSPdLasTh+0= ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=ft97nbcy; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf18.hostedemail.com: domain of roman.gushchin@linux.dev designates 91.218.175.206 as permitted sender) smtp.mailfrom=roman.gushchin@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1696896601; 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-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=6BDA26poRN0lVkuNk023R6ElLY4Pdz30rttSzJzWmU0=; b=SqvuqYWUnKaqTlWT3yjHxDrTkZhqQTblKEwy40mlUu9sPp7US/Ksu0qGEHsmVwM5F/yomH vPeT5JNLjpY4E+qF6x8RpvYRI7RK4NeV9ZJCSt2rsWxrsqm0XPoZj0A+vtcaOBJ8XgLXdf jzYedzWYRlCo10AlGnJV4fILKFo/+ZM= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1696896599; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=6BDA26poRN0lVkuNk023R6ElLY4Pdz30rttSzJzWmU0=; b=ft97nbcyFPqeUqZ4lisCE8IdqHS0q8h0Wnsl4HIdSRB7hY45IRuQS+OuTRiaAGnlAil0tV 6n6m78HGgBIkfz0ByXmzPARF8sfyEGsDiqZLrbTdayMXeSR6UAx8qwH0gjpYcPSmPHKjtQ qzYOWVCL8FrVR9Z2F277gR71ZjBKiJU= From: Roman Gushchin To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Johannes Weiner , Michal Hocko , Shakeel Butt , Muchun Song , Dennis Zhou , Andrew Morton , David Rientjes , Vlastimil Babka , Naresh Kamboju , Roman Gushchin Subject: [PATCH v2 1/5] mm: kmem: optimize get_obj_cgroup_from_current() Date: Mon, 9 Oct 2023 17:09:25 -0700 Message-ID: <20231010000929.450702-2-roman.gushchin@linux.dev> In-Reply-To: <20231010000929.450702-1-roman.gushchin@linux.dev> References: <20231010000929.450702-1-roman.gushchin@linux.dev> MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: CBE9A1C0004 X-Stat-Signature: 47kgt8wp94c8otrcd4et1qjtjjinuzoe X-HE-Tag: 1696896600-877202 X-HE-Meta: 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 y420tM1u OgEbadXj5VguD1zjQKIoLbkPPgNV1lbbvHyXWQQb3E9ozARd8gooKy0B3rm6CkYzt9tdcF0wMGD4sbDJBxaOcNL2QZ1QCdGBeK6bonMWTMYrykskHk8taJgh6Hd2Lmy552wU+rW9VEN6hyMyL2q9Ay4I6K9JYeHHwErpummLqto2tvK1SCtqz1q5xMM/Y4rhqAFZ2sa5xOosNlRrpMrDxERKzrA== 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: Manually inline memcg_kmem_bypass() and active_memcg() to speed up get_obj_cgroup_from_current() by avoiding duplicate in_task() checks and active_memcg() readings. Also add a likely() macro to __get_obj_cgroup_from_memcg(): obj_cgroup_tryget() should succeed at almost all times except a very unlikely race with the memcg deletion path. Signed-off-by: Roman Gushchin (Cruise) Acked-by: Shakeel Butt Acked-by: Johannes Weiner --- mm/memcontrol.c | 34 ++++++++++++++-------------------- 1 file changed, 14 insertions(+), 20 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 9741d62d0424..16ac2a5838fb 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1068,19 +1068,6 @@ struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm) } EXPORT_SYMBOL(get_mem_cgroup_from_mm); -static __always_inline bool memcg_kmem_bypass(void) -{ - /* Allow remote memcg charging from any context. */ - if (unlikely(active_memcg())) - return false; - - /* Memcg to charge can't be determined. */ - if (!in_task() || !current->mm || (current->flags & PF_KTHREAD)) - return true; - - return false; -} - /** * mem_cgroup_iter - iterate over memory cgroup hierarchy * @root: hierarchy root @@ -3007,7 +2994,7 @@ static struct obj_cgroup *__get_obj_cgroup_from_memcg(struct mem_cgroup *memcg) for (; !mem_cgroup_is_root(memcg); memcg = parent_mem_cgroup(memcg)) { objcg = rcu_dereference(memcg->objcg); - if (objcg && obj_cgroup_tryget(objcg)) + if (likely(objcg && obj_cgroup_tryget(objcg))) break; objcg = NULL; } @@ -3016,16 +3003,23 @@ static struct obj_cgroup *__get_obj_cgroup_from_memcg(struct mem_cgroup *memcg) __always_inline struct obj_cgroup *get_obj_cgroup_from_current(void) { - struct obj_cgroup *objcg = NULL; struct mem_cgroup *memcg; + struct obj_cgroup *objcg; - if (memcg_kmem_bypass()) - return NULL; + if (in_task()) { + memcg = current->active_memcg; + + /* Memcg to charge can't be determined. */ + if (likely(!memcg) && (!current->mm || (current->flags & PF_KTHREAD))) + return NULL; + } else { + memcg = this_cpu_read(int_active_memcg); + if (likely(!memcg)) + return NULL; + } rcu_read_lock(); - if (unlikely(active_memcg())) - memcg = active_memcg(); - else + if (!memcg) memcg = mem_cgroup_from_task(current); objcg = __get_obj_cgroup_from_memcg(memcg); rcu_read_unlock(); From patchwork Tue Oct 10 00:09:26 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roman Gushchin X-Patchwork-Id: 13414696 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 9390FE95A9C for ; Tue, 10 Oct 2023 00:10:07 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 277868D009E; Mon, 9 Oct 2023 20:10:07 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 230D68D0089; Mon, 9 Oct 2023 20:10:07 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0839A8D009E; Mon, 9 Oct 2023 20:10:07 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id E56328D0089 for ; Mon, 9 Oct 2023 20:10:06 -0400 (EDT) Received: from smtpin30.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id B8EDC12044D for ; Tue, 10 Oct 2023 00:10:06 +0000 (UTC) X-FDA: 81327619212.30.FD7F94F Received: from out-193.mta0.migadu.com (out-193.mta0.migadu.com [91.218.175.193]) by imf19.hostedemail.com (Postfix) with ESMTP id 1FBD11A0021 for ; Tue, 10 Oct 2023 00:10:04 +0000 (UTC) Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=vYGiTYSo; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf19.hostedemail.com: domain of roman.gushchin@linux.dev designates 91.218.175.193 as permitted sender) smtp.mailfrom=roman.gushchin@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1696896605; 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-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=UB8UCsgBBNwm/lYUhug39JXjgrJB25jOFlVEA0SwZ1w=; b=1JqnYqNyXV3/MeTi5CfTz8ER7RI7TKY1mgTVFlNdNkpd4HI5I+3zx0x7CjM2e8kPoU63iR dpo6amkKnSDUj6N6A2KOxbkBJpVuBRQUPj5fMGTS78Rvz/bzmPffzuXtOCxM+v0upn3/iF 5cF2t4yVjz7U+iHTn8qPcJXO6PFfTs4= ARC-Authentication-Results: i=1; imf19.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=vYGiTYSo; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf19.hostedemail.com: domain of roman.gushchin@linux.dev designates 91.218.175.193 as permitted sender) smtp.mailfrom=roman.gushchin@linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1696896605; a=rsa-sha256; cv=none; b=33MnDCpgfI9zOotGd5GGKe5whylu6J55Vxs6PRO/URTMmpbyQHJJbdRWAU0w+uje/px38D I2WDmLleXUt0iTfseZmcNEP1Pq4MSkDCuK94fq7Yg6Lk0i+hgeMWvY4x3aS0FYvUkF2aYR Ii6M8J7o3tTcKNFDgyEvh+B9I7HWHVo= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1696896601; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=UB8UCsgBBNwm/lYUhug39JXjgrJB25jOFlVEA0SwZ1w=; b=vYGiTYSof5OwIfp3SCsmVVAqIIOHV/2QRu9KSEpIse6pPitUQLPoDY3+768geHIe1OotqT gQVtl8qNLJ/m8/vVb6QjGtwGNF5Ng1ivDTPPJOXsC152HcMV8t2pO85z3+N7HypmzHOCBd PAkUbeSbCfQEs0F1f4lfujM5IDfCuz4= From: Roman Gushchin To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Johannes Weiner , Michal Hocko , Shakeel Butt , Muchun Song , Dennis Zhou , Andrew Morton , David Rientjes , Vlastimil Babka , Naresh Kamboju , Roman Gushchin Subject: [PATCH v2 2/5] mm: kmem: add direct objcg pointer to task_struct Date: Mon, 9 Oct 2023 17:09:26 -0700 Message-ID: <20231010000929.450702-3-roman.gushchin@linux.dev> In-Reply-To: <20231010000929.450702-1-roman.gushchin@linux.dev> References: <20231010000929.450702-1-roman.gushchin@linux.dev> MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: 1FBD11A0021 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: sghkfaompwmmidaia8yqpxb6pht5hkdx X-HE-Tag: 1696896604-2488 X-HE-Meta: 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 YXMkno6E sarChOJjRqTISzFXoE7BpB2zEkrPaPWDAdELEWCx62ns0fcbgFa9E7L+Okextj6Xij/sJmHOwszEY1CmbPCqljaNGydPXgXC9H10ENuCn6cSsRjzkAqhxAMyBV7/bAKGsOE86bMXIstNom4yUShGy9PuwXGs4txwBVjc010hmoTElTv3VnyruxpZakg== 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: To charge a freshly allocated kernel object to a memory cgroup, the kernel needs to obtain an objcg pointer. Currently it does it indirectly by obtaining the memcg pointer first and then calling to __get_obj_cgroup_from_memcg(). Usually tasks spend their entire life belonging to the same object cgroup. So it makes sense to save the objcg pointer on task_struct directly, so it can be obtained faster. It requires some work on fork, exit and cgroup migrate paths, but these paths are way colder. To avoid any costly synchronization the following rules are applied: 1) A task sets it's objcg pointer itself. 2) If a task is being migrated to another cgroup, the least significant bit of the objcg pointer is set atomically. 3) On the allocation path the objcg pointer is obtained locklessly using the READ_ONCE() macro and the least significant bit is checked. If it's set, the following procedure is used to update it locklessly: - task->objcg is zeroed using cmpxcg - new objcg pointer is obtained - task->objcg is updated using try_cmpxchg - operation is repeated if try_cmpxcg fails It guarantees that no updates will be lost if task migration is racing against objcg pointer update. It also allows to keep both read and write paths fully lockless. Because the task is keeping a reference to the objcg, it can't go away while the task is alive. This commit doesn't change the way the remote memcg charging works. Signed-off-by: Roman Gushchin (Cruise) Acked-by: Johannes Weiner --- include/linux/sched.h | 4 ++ mm/memcontrol.c | 130 +++++++++++++++++++++++++++++++++++++++--- 2 files changed, 125 insertions(+), 9 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 77f01ac385f7..60de42715b56 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1443,6 +1443,10 @@ struct task_struct { struct mem_cgroup *active_memcg; #endif +#ifdef CONFIG_MEMCG_KMEM + struct obj_cgroup *objcg; +#endif + #ifdef CONFIG_BLK_CGROUP struct gendisk *throttle_disk; #endif diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 16ac2a5838fb..a2efeea43058 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -249,6 +249,8 @@ struct mem_cgroup *vmpressure_to_memcg(struct vmpressure *vmpr) return container_of(vmpr, struct mem_cgroup, vmpressure); } +#define CURRENT_OBJCG_UPDATE_FLAG 0x1UL + #ifdef CONFIG_MEMCG_KMEM static DEFINE_SPINLOCK(objcg_lock); @@ -3001,6 +3003,50 @@ static struct obj_cgroup *__get_obj_cgroup_from_memcg(struct mem_cgroup *memcg) return objcg; } +static struct obj_cgroup *current_objcg_update(void) +{ + struct mem_cgroup *memcg; + struct obj_cgroup *old, *objcg = NULL; + + do { + /* Atomically drop the update bit. */ + old = xchg(¤t->objcg, NULL); + if (old) { + old = (struct obj_cgroup *) + ((unsigned long)old & ~CURRENT_OBJCG_UPDATE_FLAG); + if (old) + obj_cgroup_put(old); + + old = NULL; + } + + /* Obtain the new objcg pointer. */ + rcu_read_lock(); + memcg = mem_cgroup_from_task(current); + /* + * The current task can be asynchronously moved to another + * memcg and the previous memcg can be offlined. So let's + * get the memcg pointer and try get a reference to objcg + * under a rcu read lock. + */ + for (; memcg != root_mem_cgroup; memcg = parent_mem_cgroup(memcg)) { + objcg = rcu_dereference(memcg->objcg); + if (likely(objcg && obj_cgroup_tryget(objcg))) + break; + objcg = NULL; + } + rcu_read_unlock(); + + /* + * Try set up a new objcg pointer atomically. If it + * fails, it means the update flag was set concurrently, so + * the whole procedure should be repeated. + */ + } while (!try_cmpxchg(¤t->objcg, &old, objcg)); + + return objcg; +} + __always_inline struct obj_cgroup *get_obj_cgroup_from_current(void) { struct mem_cgroup *memcg; @@ -3008,19 +3054,26 @@ __always_inline struct obj_cgroup *get_obj_cgroup_from_current(void) if (in_task()) { memcg = current->active_memcg; + if (unlikely(memcg)) + goto from_memcg; - /* Memcg to charge can't be determined. */ - if (likely(!memcg) && (!current->mm || (current->flags & PF_KTHREAD))) - return NULL; + objcg = READ_ONCE(current->objcg); + if (unlikely((unsigned long)objcg & CURRENT_OBJCG_UPDATE_FLAG)) + objcg = current_objcg_update(); + + if (objcg) { + obj_cgroup_get(objcg); + return objcg; + } } else { memcg = this_cpu_read(int_active_memcg); - if (likely(!memcg)) - return NULL; + if (unlikely(memcg)) + goto from_memcg; } + return NULL; +from_memcg: rcu_read_lock(); - if (!memcg) - memcg = mem_cgroup_from_task(current); objcg = __get_obj_cgroup_from_memcg(memcg); rcu_read_unlock(); return objcg; @@ -6345,6 +6398,7 @@ static void mem_cgroup_move_task(void) mem_cgroup_clear_mc(); } } + #else /* !CONFIG_MMU */ static int mem_cgroup_can_attach(struct cgroup_taskset *tset) { @@ -6358,8 +6412,39 @@ static void mem_cgroup_move_task(void) } #endif +#ifdef CONFIG_MEMCG_KMEM +static void mem_cgroup_fork(struct task_struct *task) +{ + /* + * Set the update flag to cause task->objcg to be initialized lazily + * on the first allocation. It can be done without any synchronization + * because it's always performed on the current task, so does + * current_objcg_update(). + */ + task->objcg = (struct obj_cgroup *)CURRENT_OBJCG_UPDATE_FLAG; +} + +static void mem_cgroup_exit(struct task_struct *task) +{ + struct obj_cgroup *objcg = task->objcg; + + objcg = (struct obj_cgroup *) + ((unsigned long)objcg & ~CURRENT_OBJCG_UPDATE_FLAG); + if (objcg) + obj_cgroup_put(objcg); + + /* + * Some kernel allocations can happen after this point, + * but let's ignore them. It can be done without any synchronization + * because it's always performed on the current task, so does + * current_objcg_update(). + */ + task->objcg = NULL; +} +#endif + #ifdef CONFIG_LRU_GEN -static void mem_cgroup_attach(struct cgroup_taskset *tset) +static void mem_cgroup_lru_gen_attach(struct cgroup_taskset *tset) { struct task_struct *task; struct cgroup_subsys_state *css; @@ -6377,10 +6462,31 @@ static void mem_cgroup_attach(struct cgroup_taskset *tset) task_unlock(task); } #else +static void mem_cgroup_lru_gen_attach(struct cgroup_taskset *tset) {} +#endif /* CONFIG_LRU_GEN */ + +#ifdef CONFIG_MEMCG_KMEM +static void mem_cgroup_kmem_attach(struct cgroup_taskset *tset) +{ + struct task_struct *task; + struct cgroup_subsys_state *css; + + cgroup_taskset_for_each(task, css, tset) { + /* atomically set the update bit */ + set_bit(0, (unsigned long *)¤t->objcg); + } +} +#else +static void mem_cgroup_kmem_attach(struct cgroup_taskset *tset) {} +#endif /* CONFIG_MEMCG_KMEM */ + +#if defined(CONFIG_LRU_GEN) || defined(CONFIG_MEMCG_KMEM) static void mem_cgroup_attach(struct cgroup_taskset *tset) { + mem_cgroup_lru_gen_attach(tset); + mem_cgroup_kmem_attach(tset); } -#endif /* CONFIG_LRU_GEN */ +#endif static int seq_puts_memcg_tunable(struct seq_file *m, unsigned long value) { @@ -6824,9 +6930,15 @@ struct cgroup_subsys memory_cgrp_subsys = { .css_reset = mem_cgroup_css_reset, .css_rstat_flush = mem_cgroup_css_rstat_flush, .can_attach = mem_cgroup_can_attach, +#if defined(CONFIG_LRU_GEN) || defined(CONFIG_MEMCG_KMEM) .attach = mem_cgroup_attach, +#endif .cancel_attach = mem_cgroup_cancel_attach, .post_attach = mem_cgroup_move_task, +#ifdef CONFIG_MEMCG_KMEM + .fork = mem_cgroup_fork, + .exit = mem_cgroup_exit, +#endif .dfl_cftypes = memory_files, .legacy_cftypes = mem_cgroup_legacy_files, .early_init = 0, From patchwork Tue Oct 10 00:09:27 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roman Gushchin X-Patchwork-Id: 13414697 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 8730FE95A97 for ; Tue, 10 Oct 2023 00:10:09 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3AFB18D00A0; Mon, 9 Oct 2023 20:10:08 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 338878D0089; Mon, 9 Oct 2023 20:10:08 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1637E8D00A0; Mon, 9 Oct 2023 20:10:08 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id F3C028D0089 for ; Mon, 9 Oct 2023 20:10:07 -0400 (EDT) Received: from smtpin24.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id CAB17140451 for ; Tue, 10 Oct 2023 00:10:07 +0000 (UTC) X-FDA: 81327619254.24.320A4A7 Received: from out-197.mta0.migadu.com (out-197.mta0.migadu.com [91.218.175.197]) by imf23.hostedemail.com (Postfix) with ESMTP id 17AF8140015 for ; Tue, 10 Oct 2023 00:10:05 +0000 (UTC) Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=qLsl13mT; spf=pass (imf23.hostedemail.com: domain of roman.gushchin@linux.dev designates 91.218.175.197 as permitted sender) smtp.mailfrom=roman.gushchin@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1696896606; 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-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=jfnE2/YTK2KTtvwJ+nJA5/HU7PGBa8pUnySPUFyhBIQ=; b=TJjcd/wewG9xijQ9jMUiKXqOf4bG7RhA3wM9U9YLKMMr13RcYBXpliKX5p2bzgRDZpkh1e 3W3n1TXn1xEiKqm3xap00pcoQroTiD4hV2QALCjRryA0JDJ3OlbzbITuREVwVdHtM7lJJA iWpp5mZmRDMPFgmwK4lglYvL1jLrK08= ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=qLsl13mT; spf=pass (imf23.hostedemail.com: domain of roman.gushchin@linux.dev designates 91.218.175.197 as permitted sender) smtp.mailfrom=roman.gushchin@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1696896606; a=rsa-sha256; cv=none; b=W/ptSWQdY4JfXd86F6aa11kDtlfHTtbjNdXD+kBaGzETjYGhECAoM2C3Pe0P2EysSfRbNE MUCTOenfX9KF7bVRRmUL5xe1CmsV3Ih2vulEdnH+EvTiBrjrPlOswaNGunJ3BsG5xc8EGL i9eADYQpOEmkhtdg+NZ1P9vAOIwnwQc= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1696896604; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=jfnE2/YTK2KTtvwJ+nJA5/HU7PGBa8pUnySPUFyhBIQ=; b=qLsl13mTbXz/4i7wT4UNbU/Yuhrs6p0pMqUkgW5cQutUavEUX53hOM0UdEJeTs+zo2p5sJ GQojwhgKw9URgh6Cnj8JskC/4by4Jp7qKD398cvjsd/sOFJjD43axUombC6Fgh4TUL5CuQ PNw7ZFBmb9QNHRWuBYOV43b0EnZyUDM= From: Roman Gushchin To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Johannes Weiner , Michal Hocko , Shakeel Butt , Muchun Song , Dennis Zhou , Andrew Morton , David Rientjes , Vlastimil Babka , Naresh Kamboju , Roman Gushchin Subject: [PATCH v2 3/5] mm: kmem: make memcg keep a reference to the original objcg Date: Mon, 9 Oct 2023 17:09:27 -0700 Message-ID: <20231010000929.450702-4-roman.gushchin@linux.dev> In-Reply-To: <20231010000929.450702-1-roman.gushchin@linux.dev> References: <20231010000929.450702-1-roman.gushchin@linux.dev> MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: 17AF8140015 X-Rspam-User: X-Stat-Signature: aqwzh44yi7dciz6xmjbysqayar51orkq X-Rspamd-Server: rspam01 X-HE-Tag: 1696896605-923645 X-HE-Meta: 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 SyAY9DUi jKPveUq8+Hpt1Xuq4BAP9Mj6Vf6zvK7g2Lj7+orzR2gtCT/2JKiB11jpFKl8g9KNEyPMp4ANsh+7r2ww= 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: Keep a reference to the original objcg object for the entire life of a memcg structure. This allows to simplify the synchronization on the kernel memory allocation paths: pinning a (live) memcg will also pin the corresponding objcg. The memory overhead of this change is minimal because object cgroups usually outlive their corresponding memory cgroups even without this change, so it's only an additional pointer per memcg. Signed-off-by: Roman Gushchin (Cruise) Acked-by: Shakeel Butt --- include/linux/memcontrol.h | 8 +++++++- mm/memcontrol.c | 5 +++++ 2 files changed, 12 insertions(+), 1 deletion(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index ab94ad4597d0..277690af383d 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -299,7 +299,13 @@ struct mem_cgroup { #ifdef CONFIG_MEMCG_KMEM int kmemcg_id; - struct obj_cgroup __rcu *objcg; + /* + * memcg->objcg is wiped out as a part of the objcg repaprenting + * process. memcg->orig_objcg preserves a pointer (and a reference) + * to the original objcg until the end of live of memcg. + */ + struct obj_cgroup __rcu *objcg; + struct obj_cgroup *orig_objcg; /* list of inherited objcgs, protected by objcg_lock */ struct list_head objcg_list; #endif diff --git a/mm/memcontrol.c b/mm/memcontrol.c index a2efeea43058..490c5f67be79 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3808,6 +3808,8 @@ static int memcg_online_kmem(struct mem_cgroup *memcg) objcg->memcg = memcg; rcu_assign_pointer(memcg->objcg, objcg); + obj_cgroup_get(objcg); + memcg->orig_objcg = objcg; static_branch_enable(&memcg_kmem_online_key); @@ -5302,6 +5304,9 @@ static void __mem_cgroup_free(struct mem_cgroup *memcg) { int node; + if (memcg->orig_objcg) + obj_cgroup_put(memcg->orig_objcg); + for_each_node(node) free_mem_cgroup_per_node_info(memcg, node); kfree(memcg->vmstats); From patchwork Tue Oct 10 00:09:28 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roman Gushchin X-Patchwork-Id: 13414698 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 520C2E95A9C for ; Tue, 10 Oct 2023 00:10:12 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3BAE18D00A1; Mon, 9 Oct 2023 20:10:11 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 312648D0089; Mon, 9 Oct 2023 20:10:11 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 163498D00A1; Mon, 9 Oct 2023 20:10:11 -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 EE6798D0089 for ; Mon, 9 Oct 2023 20:10:10 -0400 (EDT) Received: from smtpin26.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id C2ACB1CAA94 for ; Tue, 10 Oct 2023 00:10:10 +0000 (UTC) X-FDA: 81327619380.26.88D1808 Received: from out-207.mta0.migadu.com (out-207.mta0.migadu.com [91.218.175.207]) by imf06.hostedemail.com (Postfix) with ESMTP id EFFBB180014 for ; Tue, 10 Oct 2023 00:10:08 +0000 (UTC) Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="M/HNb3YK"; spf=pass (imf06.hostedemail.com: domain of roman.gushchin@linux.dev designates 91.218.175.207 as permitted sender) smtp.mailfrom=roman.gushchin@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1696896609; a=rsa-sha256; cv=none; b=hF214hcgT08069fL9SUOqnT+O5hI1w7nKg70xI3Vr/or52KlvriZkM082UcIA7Jk66KqbF trdbb1Za+0a3LOtT0lwHLUh/Zk28TmCPWxuv26M2DeQT07t5+gX3hHkfkTriCGOG+Po5OI uBt/yGPvwltbGjCnrlnJhBrdM8gFpHI= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="M/HNb3YK"; spf=pass (imf06.hostedemail.com: domain of roman.gushchin@linux.dev designates 91.218.175.207 as permitted sender) smtp.mailfrom=roman.gushchin@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1696896609; 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-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=vaNtRxcBkqs+qNsGw0HnKynEFDwRPPwwrEaTCT/4xFw=; b=WKZ4+3JC9Uae6voc+pqT1veiD3EqptuC/oNxeanhnAk2SJVN7dtOzDdhFXqbYnr7ODJDID 8/4vcchVB27Jc15eH17XxdmXRDuLkVMC32b6iDjuZdMPCJa3wAwuursZYwtF0lNd7zk9PX 9n39I7eXr8tpyk7ApnFBdBhLiUeKD8c= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1696896607; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=vaNtRxcBkqs+qNsGw0HnKynEFDwRPPwwrEaTCT/4xFw=; b=M/HNb3YKc2bGW5FqYd/GesbtjL4WMaYzcJf13vLo0uLcpBE3PKKz+0p+JT6Cdmcu7vY5Yn RNsW9yYFROw7J8lJJuMjKiT3ExifQsuvx6IMfw/EZFZy1RZTpeDFncxOFPz8hXFU61Wa2S ta2O/F0zqFj/J+i3jJVN9WgsTLIfc8Q= From: Roman Gushchin To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Johannes Weiner , Michal Hocko , Shakeel Butt , Muchun Song , Dennis Zhou , Andrew Morton , David Rientjes , Vlastimil Babka , Naresh Kamboju , Roman Gushchin Subject: [PATCH v2 4/5] mm: kmem: scoped objcg protection Date: Mon, 9 Oct 2023 17:09:28 -0700 Message-ID: <20231010000929.450702-5-roman.gushchin@linux.dev> In-Reply-To: <20231010000929.450702-1-roman.gushchin@linux.dev> References: <20231010000929.450702-1-roman.gushchin@linux.dev> MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: EFFBB180014 X-Stat-Signature: yd3erdds9sz5y1f6xw7ewgpb9hqrcbwt X-Rspam-User: X-HE-Tag: 1696896608-156837 X-HE-Meta: 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 n2TEvPNW qo8oaKRs6L+dPJFSHk6QzwZqN8kwt3DdsomM5WBhJKfCvsL4S1fEay2tliN0CLhKfOVmZ 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: Switch to a scope-based protection of the objcg pointer on slab/kmem allocation paths. Instead of using the get_() semantics in the pre-allocation hook and put the reference afterwards, let's rely on the fact that objcg is pinned by the scope. It's possible because: 1) if the objcg is received from the current task struct, the task is keeping a reference to the objcg. 2) if the objcg is received from an active memcg (remote charging), the memcg is pinned by the scope and has a reference to the corresponding objcg. Signed-off-by: Roman Gushchin (Cruise) Acked-by: Shakeel Butt --- include/linux/memcontrol.h | 6 +++++ mm/memcontrol.c | 47 ++++++++++++++++++++++++++++++++++++-- mm/slab.h | 10 +++----- 3 files changed, 54 insertions(+), 9 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 277690af383d..0e53b890f063 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -1769,6 +1769,12 @@ bool mem_cgroup_kmem_disabled(void); int __memcg_kmem_charge_page(struct page *page, gfp_t gfp, int order); void __memcg_kmem_uncharge_page(struct page *page, int order); +/* + * The returned objcg pointer is safe to use without additional + * protection within a scope, refer to the implementation for the + * additional details. + */ +struct obj_cgroup *current_obj_cgroup(void); struct obj_cgroup *get_obj_cgroup_from_current(void); struct obj_cgroup *get_obj_cgroup_from_folio(struct folio *folio); diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 490c5f67be79..84724fb875ce 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3079,6 +3079,49 @@ __always_inline struct obj_cgroup *get_obj_cgroup_from_current(void) return objcg; } +__always_inline struct obj_cgroup *current_obj_cgroup(void) +{ + struct mem_cgroup *memcg; + struct obj_cgroup *objcg; + + if (in_task()) { + memcg = current->active_memcg; + if (unlikely(memcg)) + goto from_memcg; + + objcg = READ_ONCE(current->objcg); + if (unlikely((unsigned long)objcg & CURRENT_OBJCG_UPDATE_FLAG)) + objcg = current_objcg_update(); + /* + * Objcg reference is kept by the task, so it's safe + * to use the objcg by the current task. + */ + return objcg; + } + + memcg = this_cpu_read(int_active_memcg); + if (unlikely(memcg)) + goto from_memcg; + + return NULL; + +from_memcg: + for (; !mem_cgroup_is_root(memcg); memcg = parent_mem_cgroup(memcg)) { + /* + * Memcg pointer is protected by scope (see set_active_memcg()) + * and is pinning the corresponding objcg, so objcg can't go + * away and can be used within the scope without any additional + * protection. + */ + objcg = rcu_dereference_check(memcg->objcg, 1); + if (likely(objcg)) + break; + objcg = NULL; + } + + return objcg; +} + struct obj_cgroup *get_obj_cgroup_from_folio(struct folio *folio) { struct obj_cgroup *objcg; @@ -3173,15 +3216,15 @@ int __memcg_kmem_charge_page(struct page *page, gfp_t gfp, int order) struct obj_cgroup *objcg; int ret = 0; - objcg = get_obj_cgroup_from_current(); + objcg = current_obj_cgroup(); if (objcg) { ret = obj_cgroup_charge_pages(objcg, gfp, 1 << order); if (!ret) { + obj_cgroup_get(objcg); page->memcg_data = (unsigned long)objcg | MEMCG_DATA_KMEM; return 0; } - obj_cgroup_put(objcg); } return ret; } diff --git a/mm/slab.h b/mm/slab.h index 799a315695c6..8cd3294fedf5 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -484,7 +484,7 @@ static inline bool memcg_slab_pre_alloc_hook(struct kmem_cache *s, if (!(flags & __GFP_ACCOUNT) && !(s->flags & SLAB_ACCOUNT)) return true; - objcg = get_obj_cgroup_from_current(); + objcg = current_obj_cgroup(); if (!objcg) return true; @@ -497,17 +497,14 @@ static inline bool memcg_slab_pre_alloc_hook(struct kmem_cache *s, css_put(&memcg->css); if (ret) - goto out; + return false; } if (obj_cgroup_charge(objcg, flags, objects * obj_full_size(s))) - goto out; + return false; *objcgp = objcg; return true; -out: - obj_cgroup_put(objcg); - return false; } static inline void memcg_slab_post_alloc_hook(struct kmem_cache *s, @@ -542,7 +539,6 @@ static inline void memcg_slab_post_alloc_hook(struct kmem_cache *s, obj_cgroup_uncharge(objcg, obj_full_size(s)); } } - obj_cgroup_put(objcg); } static inline void memcg_slab_free_hook(struct kmem_cache *s, struct slab *slab, From patchwork Tue Oct 10 00:09:29 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roman Gushchin X-Patchwork-Id: 13414699 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 32F84CD68E3 for ; Tue, 10 Oct 2023 00:10:15 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id EAB4D8D00A2; 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DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1696896610; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=j6TjL0tOzMm9uw8Y9niPXJ1ezOtPxfS6WilpL+cESRE=; b=ZGPVwiM2h+XunCiZLqM4FyYGsiSKjC0phq0S+wyUEtVkyO+vvaGmE0lOyAzfhgRkZqIQVI z+aLmjDpmuOiL6ag53Op+5oV0AIkM4FSmAvmbCqi/H5wKmFVEnAUYzw7h9+t++JC6EK5WG wCu/Uex1P/e7AHO9YRFh11WGzRmaLv8= From: Roman Gushchin To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Johannes Weiner , Michal Hocko , Shakeel Butt , Muchun Song , Dennis Zhou , Andrew Morton , David Rientjes , Vlastimil Babka , Naresh Kamboju , Roman Gushchin Subject: [PATCH v2 5/5] percpu: scoped objcg protection Date: Mon, 9 Oct 2023 17:09:29 -0700 Message-ID: <20231010000929.450702-6-roman.gushchin@linux.dev> In-Reply-To: <20231010000929.450702-1-roman.gushchin@linux.dev> References: <20231010000929.450702-1-roman.gushchin@linux.dev> MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: DD3E84000B X-Stat-Signature: banmq63wrodjqtxfkd9scftkuqxukg34 X-Rspam-User: X-HE-Tag: 1696896611-690962 X-HE-Meta: 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 ADDfIBv1 VM20BySNeXncDzSgFOE6RYCrBIelD7Rl28yBkmrWvjlvOo+ZBfZrPMcY3RHTu9AhpncLc 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: Similar to slab and kmem, switch to a scope-based protection of the objcg pointer to avoid. Signed-off-by: Roman Gushchin (Cruise) Acked-by: Shakeel Butt --- mm/percpu.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/mm/percpu.c b/mm/percpu.c index a7665de8485f..f53ba692d67a 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -1628,14 +1628,12 @@ static bool pcpu_memcg_pre_alloc_hook(size_t size, gfp_t gfp, if (!memcg_kmem_online() || !(gfp & __GFP_ACCOUNT)) return true; - objcg = get_obj_cgroup_from_current(); + objcg = current_obj_cgroup(); if (!objcg) return true; - if (obj_cgroup_charge(objcg, gfp, pcpu_obj_full_size(size))) { - obj_cgroup_put(objcg); + if (obj_cgroup_charge(objcg, gfp, pcpu_obj_full_size(size))) return false; - } *objcgp = objcg; return true; @@ -1649,6 +1647,7 @@ static void pcpu_memcg_post_alloc_hook(struct obj_cgroup *objcg, return; if (likely(chunk && chunk->obj_cgroups)) { + obj_cgroup_get(objcg); chunk->obj_cgroups[off >> PCPU_MIN_ALLOC_SHIFT] = objcg; rcu_read_lock(); @@ -1657,7 +1656,6 @@ static void pcpu_memcg_post_alloc_hook(struct obj_cgroup *objcg, rcu_read_unlock(); } else { obj_cgroup_uncharge(objcg, pcpu_obj_full_size(size)); - obj_cgroup_put(objcg); } }