From patchwork Thu Apr 6 01:56:28 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ye Bin X-Patchwork-Id: 80022 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:b0ea:0:b0:3b6:4342:cba0 with SMTP id b10csp711840vqo; Wed, 5 Apr 2023 18:59:10 -0700 (PDT) X-Google-Smtp-Source: AKy350bvHyppI/okMbIvHY8FOr7FkjbwCqiFyLccuJSoZVpcno7wrVEYXpDKdduzbvvs9LOfC0a0 X-Received: by 2002:a17:906:f8c9:b0:947:eaed:1f87 with SMTP id lh9-20020a170906f8c900b00947eaed1f87mr4097231ejb.19.1680746350000; Wed, 05 Apr 2023 18:59:10 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1680746349; cv=none; d=google.com; s=arc-20160816; b=etmjgjAtsy9JbYOzFn71Ch3IGhbReadMZBKn8B42kfpKRxO+KZrmQ15ql0Gv4Y3JQH 2f+axIwnJ4oG7LQ7l1Guu/+0X3rP6Hzb6kvE77DcZE0Z+K0HJhUoEPv7+KVdiI7ouy8X tJh+VjoxjFuKhXPe4ueA1POwWAHyrczGaC7knAppdVCGKVL6rSQb/G6Oi23Hq/RYKxyq pQjeRk5Hvkzhly833SCfnnpy0vf9Ep+gDye2kr2RCrdvxUtHisKYNHAsOaaUTgRuuq9O pyXkoNYfyePgYSMs666iNC/ncZ0rf/nJd4kQKI1QKUGiio+Ju02kbFQVjnLUzewwRNts h1bA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from; bh=GN+sUs27ysqTC3ebxS5dgKiSF9/pny2Yx3svyi9Q5KY=; b=JmHY7cO/zR9PXTTh7v2yoLz86sfrmL/HK1gBZMUOY93vHhMp28LGoGSYmRQty1+GWL jpGLU/W7XzHfB/jtYjo81dnZQt63XY8X3AioakbvnJ0skWOc0WcSDts7ZJ+Uiu1fTgmc qcrCBaZHd2KA80O8rmkhd99DHbf3LyunjEHq82ofhdCQSVYU1aPPTn+r1Le9Noh76Nzu P0CgY/yySEwodvzHxx8T+q4DndT+xmYNgjlYyAIu9uiWKnWwZW3FKKEGePSQ5nfMoUy3 PQB0qxmeqJOD2GXbiQF8NJoOKPE5rib3nCBDrs5VWYEc4MIczBo0YeyilqRC0o+nRyjR jnrw== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id ca9-20020a170906a3c900b009334d676751si198208ejb.609.2023.04.05.18.58.45; Wed, 05 Apr 2023 18:59:09 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234636AbjDFB5J (ORCPT + 99 others); Wed, 5 Apr 2023 21:57:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58056 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231889AbjDFB5D (ORCPT ); Wed, 5 Apr 2023 21:57:03 -0400 Received: from dggsgout12.his.huawei.com (unknown [45.249.212.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D68ABA9 for ; Wed, 5 Apr 2023 18:57:01 -0700 (PDT) Received: from mail02.huawei.com (unknown [172.30.67.169]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTP id 4PsPkd3XFqz4f3nqJ for ; Thu, 6 Apr 2023 09:56:57 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.127.227]) by APP3 (Coremail) with SMTP id _Ch0CgCnUyHoJi5kX936GA--.31319S5; Thu, 06 Apr 2023 09:56:59 +0800 (CST) From: Ye Bin To: dennis@kernel.org, tj@kernel.org, cl@linux.com, linux-mm@kvack.org, yury.norov@gmail.com, andriy.shevchenko@linux.intel.com, linux@rasmusvillemoes.dk Cc: linux-kernel@vger.kernel.org, dchinner@redhat.com, yebin10@huawei.com, yebin@huaweicloud.com Subject: [PATCH v2 1/2] cpu/hotplug: introduce 'num_dying_cpus' to get dying CPUs count Date: Thu, 6 Apr 2023 09:56:28 +0800 Message-Id: <20230406015629.1804722-2-yebin@huaweicloud.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20230406015629.1804722-1-yebin@huaweicloud.com> References: <20230406015629.1804722-1-yebin@huaweicloud.com> MIME-Version: 1.0 X-CM-TRANSID: _Ch0CgCnUyHoJi5kX936GA--.31319S5 X-Coremail-Antispam: 1UD129KBjvJXoW7WFy8ZFykGrW5KFWDCFy5CFg_yoW5JF4rpr 4UGFW5trWUAFyIga9Yyws8Xr1F9wn5Crn5Gay29F13JFy3Ja4vq3WkuFy5Jr15WrZ3ur1a vrZ0qr409a15Xa7anT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUBE14x267AKxVW5JVWrJwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_Jr4l82xGYIkIc2 x26xkF7I0E14v26r4j6ryUM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2z4x0 Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F4UJw A2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oVCq3wAS 0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2 IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0 Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwACI402YVCY1x02628vn2kIc2 xKxwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v2 6r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_Jw0_GFylIxkGc2 Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7CjxVAFwI0_ Gr0_Cr1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r1j6r4UMI IF0xvEx4A2jsIEc7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x0JU2_M3UUUUU = X-CM-SenderInfo: p1hex046kxt4xhlfz01xgou0bp/ X-CFilter-Loop: Reflected X-Spam-Status: No, score=2.1 required=5.0 tests=KHOP_HELO_FCRDNS,MAY_BE_FORGED, SPF_HELO_NONE,SPF_NONE autolearn=no autolearn_force=no version=3.4.6 X-Spam-Level: ** X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1762390284677936440?= X-GMAIL-MSGID: =?utf-8?q?1762390284677936440?= From: Ye Bin Introduce '__num_dying_cpus' variable to cache the number of dying CPUs in the core and just return the cached variable. Signed-off-by: Ye Bin --- include/linux/cpumask.h | 20 ++++++++++++++++---- kernel/cpu.c | 2 ++ 2 files changed, 18 insertions(+), 4 deletions(-) diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h index 2a61ddcf8321..8127fd598f51 100644 --- a/include/linux/cpumask.h +++ b/include/linux/cpumask.h @@ -135,6 +135,8 @@ extern struct cpumask __cpu_dying_mask; extern atomic_t __num_online_cpus; +extern atomic_t __num_dying_cpus; + extern cpumask_t cpus_booted_once_mask; static __always_inline void cpu_max_bits_warn(unsigned int cpu, unsigned int bits) @@ -1018,10 +1020,14 @@ set_cpu_active(unsigned int cpu, bool active) static __always_inline void set_cpu_dying(unsigned int cpu, bool dying) { - if (dying) - cpumask_set_cpu(cpu, &__cpu_dying_mask); - else - cpumask_clear_cpu(cpu, &__cpu_dying_mask); + if (dying) { + if (!cpumask_test_and_set_cpu(cpu, &__cpu_dying_mask)) + atomic_inc(&__num_dying_cpus); + } + else { + if (cpumask_test_and_clear_cpu(cpu, &__cpu_dying_mask)) + atomic_dec(&__num_dying_cpus); + } } /** @@ -1073,6 +1079,11 @@ static __always_inline unsigned int num_online_cpus(void) { return arch_atomic_read(&__num_online_cpus); } + +static __always_inline unsigned int num_dying_cpus(void) +{ + return arch_atomic_read(&__num_dying_cpus); +} #define num_possible_cpus() cpumask_weight(cpu_possible_mask) #define num_present_cpus() cpumask_weight(cpu_present_mask) #define num_active_cpus() cpumask_weight(cpu_active_mask) @@ -1108,6 +1119,7 @@ static __always_inline bool cpu_dying(unsigned int cpu) #define num_possible_cpus() 1U #define num_present_cpus() 1U #define num_active_cpus() 1U +#define num_dying_cpus() 0U static __always_inline bool cpu_online(unsigned int cpu) { diff --git a/kernel/cpu.c b/kernel/cpu.c index f4a2c5845bcb..1c96c04cb259 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -2662,6 +2662,8 @@ EXPORT_SYMBOL(__cpu_dying_mask); atomic_t __num_online_cpus __read_mostly; EXPORT_SYMBOL(__num_online_cpus); +atomic_t __num_dying_cpus __read_mostly; + void init_cpu_present(const struct cpumask *src) { cpumask_copy(&__cpu_present_mask, src); From patchwork Thu Apr 6 01:56:29 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ye Bin X-Patchwork-Id: 80025 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:b0ea:0:b0:3b6:4342:cba0 with SMTP id b10csp716892vqo; Wed, 5 Apr 2023 19:10:09 -0700 (PDT) X-Google-Smtp-Source: AKy350YNXNiZ5LTx1+8i19cFE2PGSHh79KZY4TWekiuPXkdjT58U9g6CUAGCjQ3CVFfcwJJ9oKsQ X-Received: by 2002:a17:90b:b12:b0:23f:a4da:1208 with SMTP id bf18-20020a17090b0b1200b0023fa4da1208mr9038827pjb.39.1680747008822; Wed, 05 Apr 2023 19:10:08 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1680747008; cv=none; d=google.com; s=arc-20160816; b=xHfe0V2ZZIfO1FTriE4gieUHP61M8jgwvBuJ2mhr9MsE4shTtrrdHNEMU7h9R+onAd McAVr+iuEFEjpfIZtndm280jOLWIZyFN9N9S32xNucEzHXXjqmjrhobdd8f7CpdpayVO mBaqCERQfDCVfu3ULPo+jTqYINuHwIOZ39kIbUyKvMhMHCVuXPseLUOL6E4eeGb7ZYuA MRfpC80lHgOuTCXkxq1Q27rYjg25zGFNLOrh2BiDOFEo1NYOihhVGbByCq6xnHCy5VlD 0ONdgMPPrGd9JDg4hqV5yYTpweNyLjSKF2L3lcBaP1P7GdD8uNWkg6KtLkehkE+uPMQW Io7g== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from; bh=7os4YebrsB+qVnoAs8abz+sYpG6SziiRn/vgzbQG0e8=; b=nOGGyT1JE2biANeWVreOZtktFxhN5dRERhQxbNLKpz7uvjBrA1qqiLUpEZvSMl+smz kdEVqBhyaFJ+8jPSRX493iTBxhyNTm520+RvDgith4c2f4+oyfkQLmMUNctECqYgvj6p 3S1vs+ilT+2zMv81yb3YSmjh4iNgDJypsosd8jLMvzg9xVfG2sVpwwWGeMJTzeif5CCo oPwlhex4m7E/m4E2mwQG4Vr24KnV+pmwJtJvfJM6Kg9r/tX60Ck1sm3ZF5ysiSmIl5Fh 4U1sgrOuJ89km62T/0/ePeCDyNQIMjzVeDgJEOqNZohMllv7KcRVN2HE+2gK745RDeU9 g0hg== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id om8-20020a17090b3a8800b002448c09e0f0si86046pjb.168.2023.04.05.19.09.55; Wed, 05 Apr 2023 19:10:08 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234651AbjDFB5M (ORCPT + 99 others); Wed, 5 Apr 2023 21:57:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58144 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234539AbjDFB5F (ORCPT ); Wed, 5 Apr 2023 21:57:05 -0400 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0A46283CE for ; Wed, 5 Apr 2023 18:57:02 -0700 (PDT) Received: from mail02.huawei.com (unknown [172.30.67.169]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4PsPkf381dz4f3v5b for ; Thu, 6 Apr 2023 09:56:58 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.127.227]) by APP3 (Coremail) with SMTP id _Ch0CgCnUyHoJi5kX936GA--.31319S6; Thu, 06 Apr 2023 09:56:59 +0800 (CST) From: Ye Bin To: dennis@kernel.org, tj@kernel.org, cl@linux.com, linux-mm@kvack.org, yury.norov@gmail.com, andriy.shevchenko@linux.intel.com, linux@rasmusvillemoes.dk Cc: linux-kernel@vger.kernel.org, dchinner@redhat.com, yebin10@huawei.com, yebin@huaweicloud.com Subject: [PATCH v2 2/2] lib/percpu_counter: fix dying cpu compare race Date: Thu, 6 Apr 2023 09:56:29 +0800 Message-Id: <20230406015629.1804722-3-yebin@huaweicloud.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20230406015629.1804722-1-yebin@huaweicloud.com> References: <20230406015629.1804722-1-yebin@huaweicloud.com> MIME-Version: 1.0 X-CM-TRANSID: _Ch0CgCnUyHoJi5kX936GA--.31319S6 X-Coremail-Antispam: 1UD129KBjvJXoW7ZFW7ArWDXw1ktFy7KFyfZwb_yoW8WFy5pr 4UKry5Jr18AF92k343Kw1vqF9I9r1kAF4rKwnrGF1fAFnxZa45urW0yrs8JF109rn7Wrya qryjgF4xCa4Yv3JanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUBE14x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_Jryl82xGYIkIc2 x26xkF7I0E14v26ryj6s0DM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2z4x0 Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F4UJw A2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oVCq3wAS 0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2 IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0 Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwACI402YVCY1x02628vn2kIc2 xKxwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v2 6r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_Jw0_GFylIxkGc2 Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7CjxVAFwI0_ Gr0_Cr1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r1j6r4UMI IF0xvEx4A2jsIEc7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x0JUHbyAUUUUU = X-CM-SenderInfo: p1hex046kxt4xhlfz01xgou0bp/ X-CFilter-Loop: Reflected X-Spam-Status: No, score=0.0 required=5.0 tests=SPF_HELO_NONE,SPF_NONE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1762390975563691343?= X-GMAIL-MSGID: =?utf-8?q?1762390975563691343?= From: Ye Bin In commit 8b57b11cca88 ("pcpcntrs: fix dying cpu summation race") a race condition between a cpu dying and percpu_counter_sum() iterating online CPUs was identified. Acctually, there's the same race condition between a cpu dying and __percpu_counter_compare(). Here, use 'num_online_cpus()' for quick judgment. But 'num_online_cpus()' will be decreased before call 'percpu_counter_cpu_dead()', then maybe return incorrect result. To solve above issue, also need to add dying CPUs count when do quick judgment in __percpu_counter_compare(). Signed-off-by: Ye Bin --- lib/percpu_counter.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c index 5004463c4f9f..399840cb0012 100644 --- a/lib/percpu_counter.c +++ b/lib/percpu_counter.c @@ -227,6 +227,15 @@ static int percpu_counter_cpu_dead(unsigned int cpu) return 0; } +static __always_inline unsigned int num_count_cpus(void) +{ +#ifdef CONFIG_HOTPLUG_CPU + return (num_online_cpus() + num_dying_cpus()); +#else + return num_online_cpus(); +#endif +} + /* * Compare counter against given value. * Return 1 if greater, 0 if equal and -1 if less @@ -237,7 +246,7 @@ int __percpu_counter_compare(struct percpu_counter *fbc, s64 rhs, s32 batch) count = percpu_counter_read(fbc); /* Check to see if rough count will be sufficient for comparison */ - if (abs(count - rhs) > (batch * num_online_cpus())) { + if (abs(count - rhs) > (batch * num_count_cpus())) { if (count > rhs) return 1; else