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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7B1E1CCFA00 for ; Mon, 3 Nov 2025 02:32:14 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D5F7F8E0018; Sun, 2 Nov 2025 21:32:13 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id D10158E0015; Sun, 2 Nov 2025 21:32:13 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BFEC18E0018; Sun, 2 Nov 2025 21:32:13 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id AE0328E0015 for ; Sun, 2 Nov 2025 21:32:13 -0500 (EST) Received: from smtpin23.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 5C53C5B7B5 for ; Mon, 3 Nov 2025 02:32:13 +0000 (UTC) X-FDA: 84067721346.23.CAD2BBE Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) by imf29.hostedemail.com (Postfix) with ESMTP id 9681112000E for ; Mon, 3 Nov 2025 02:32:09 +0000 (UTC) Authentication-Results: imf29.hostedemail.com; spf=pass (imf29.hostedemail.com: domain of chenridong@huaweicloud.com designates 45.249.212.51 as permitted sender) smtp.mailfrom=chenridong@huaweicloud.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1762137131; 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; bh=f7NJ5BHZawfzP3SjdeFGSHGjJ23dkO6ZAs2KcuU9kho=; b=SVX1q776w02VslUayt+xrKReLN7HfhTO8XRTRFI0bnhmYehQrEcxB3wCCbXa7NHg02FtVd 0PddMDe6qYcYIlWn0epvAMzmw5NdkbRNtKDo/z51O4mC1Azu+b4D7cGce2Y2csNllbBReW HFAWvzcUHCJrGv3DZMV3OdR50182fvo= ARC-Authentication-Results: i=1; imf29.hostedemail.com; dkim=none; spf=pass (imf29.hostedemail.com: domain of chenridong@huaweicloud.com designates 45.249.212.51 as permitted sender) smtp.mailfrom=chenridong@huaweicloud.com; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1762137131; a=rsa-sha256; cv=none; b=jXTmXVMof0Ql1QhavIxquMM4wNX+qp9bfQkBDSackX0WK7tLQ0u1Wse2PP7F2QXcXwQfp4 zNYiCIEVTBR4pgktIPD8CcEFroVX9TKHtbiKmthS+tU8S5+KowPXxVf7kxT0gvUlbCg+pG /CDPM4SH0J0BOo3mirMozcFQta/wrcU= Received: from mail.maildlp.com (unknown [172.19.163.216]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTPS id 4d0Fw90qwMzYQthc for ; Mon, 3 Nov 2025 10:31:53 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.112]) by mail.maildlp.com (Postfix) with ESMTP id C31441A18C4 for ; Mon, 3 Nov 2025 10:32:05 +0800 (CST) Received: from [10.67.111.176] (unknown [10.67.111.176]) by APP1 (Coremail) with SMTP id cCh0CgDHN0slFAhpPKf4CQ--.38631S2; Mon, 03 Nov 2025 10:32:05 +0800 (CST) Message-ID: <400165fe-18d5-4a78-b4bd-4e5b55de0c04@huaweicloud.com> Date: Mon, 3 Nov 2025 10:32:04 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 11/33] cpuset: Provide lockdep check for cpuset lock held To: Frederic Weisbecker Cc: LKML , =?UTF-8?Q?Michal_Koutn=C3=BD?= , Andrew Morton , Bjorn Helgaas , Catalin Marinas , Danilo Krummrich , "David S . Miller" , Eric Dumazet , Gabriele Monaco , Greg Kroah-Hartman , Ingo Molnar , Jakub Kicinski , Jens Axboe , Johannes Weiner , Lai Jiangshan , Marco Crivellari , Michal Hocko , Muchun Song , Paolo Abeni , Peter Zijlstra , Phil Auld , "Rafael J . Wysocki" , Roman Gushchin , Shakeel Butt , Simon Horman , Tejun Heo , Thomas Gleixner , Vlastimil Babka , Waiman Long , Will Deacon , cgroups@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-block@vger.kernel.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, netdev@vger.kernel.org References: <20251013203146.10162-1-frederic@kernel.org> <20251013203146.10162-12-frederic@kernel.org> Content-Language: en-US From: Chen Ridong In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-CM-TRANSID:cCh0CgDHN0slFAhpPKf4CQ--.38631S2 X-Coremail-Antispam: 1UD129KBjvJXoW7tryxCw1kAF1UJrWfKw4DJwb_yoW5Jr1rpF yDKFyrCF4rZr4UuFy2qw17uF1vqw4kWF1UGFn5tr18XasFvFn2vF1v9r1Ygr1F9rs7Gw40 vF17Wa9I9FWqyrJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUvFb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4 vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7Cj xVAFwI0_Gr1j6F4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x 0267AKxVW0oVCq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG 6I80ewAv7VC0I7IYx2IY67AKxVWUGVWUXwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFV Cjc4AY6r1j6r4UM4x0Y48IcVAKI48JM4IIrI8v6xkF7I0E8cxan2IY04v7MxkF7I0En4kS 14v26rWY6Fy7MxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I 8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWrXVW8 Jr1lIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7 CjxVAFwI0_Cr0_Gr1UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AK xVWUJVW8JwCI42IY6I8E87Iv6xkF7I0E14v26r4j6r4UJbIYCTnIWIevJa73UjIFyTuYvj xUsPfHUUUUU X-CM-SenderInfo: hfkh02xlgr0w46kxt4xhlfz01xgou0bp/ X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 9681112000E X-Stat-Signature: wmqs5zab4u3ssicbzkh6f533a53b8r3c X-Rspam-User: X-HE-Tag: 1762137129-849406 X-HE-Meta: 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 E6lWII4D VLZnpmVDcsXl9bkLW4scOjB6zUI6W51xTi0aftKF8o8Etxn0zN1JRi/JfWRk+N3bkxbbhcVB0fwV+J+QNxoD24HG2JAfYXIsxAvMQKc6bAg8keegk2/6KSJIZJsPybUyMOMIsQ/6GHEnMMwa+Ou1DWQPriji8Gtg6inaPJC2p8ize/J4= 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 2025/11/1 0:08, Frederic Weisbecker wrote: > Le Tue, Oct 14, 2025 at 09:29:25PM +0800, Chen Ridong a écrit : >> >> >> On 2025/10/14 4:31, Frederic Weisbecker wrote: >>> cpuset modifies partitions, including isolated, while holding the cpuset >>> mutex. >>> >>> This means that holding the cpuset mutex is safe to synchronize against >>> housekeeping cpumask changes. >>> >>> Provide a lockdep check to validate that. >>> >>> Signed-off-by: Frederic Weisbecker >>> --- >>> include/linux/cpuset.h | 2 ++ >>> kernel/cgroup/cpuset.c | 7 +++++++ >>> 2 files changed, 9 insertions(+) >>> >>> diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h >>> index 2ddb256187b5..051d36fec578 100644 >>> --- a/include/linux/cpuset.h >>> +++ b/include/linux/cpuset.h >>> @@ -18,6 +18,8 @@ >>> #include >>> #include >>> >>> +extern bool lockdep_is_cpuset_held(void); >>> + >>> #ifdef CONFIG_CPUSETS >>> >>> /* >>> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c >>> index 8595f1eadf23..aa1ac7bcf2ea 100644 >>> --- a/kernel/cgroup/cpuset.c >>> +++ b/kernel/cgroup/cpuset.c >>> @@ -279,6 +279,13 @@ void cpuset_full_unlock(void) >>> cpus_read_unlock(); >>> } >>> >>> +#ifdef CONFIG_LOCKDEP >>> +bool lockdep_is_cpuset_held(void) >>> +{ >>> + return lockdep_is_held(&cpuset_mutex); >>> +} >>> +#endif >>> + >>> static DEFINE_SPINLOCK(callback_lock); >>> >>> void cpuset_callback_lock_irq(void) >> >> Is the lockdep_is_cpuset_held function actually being used? >> If CONFIG_LOCKDEP is disabled, compilation would fail with an "undefined reference to >> lockdep_is_cpuset_held" error. > > Although counter-intuitive, this is how the lockdep_is_held() functions family > do work. > > This allows this kind of trick: > > if (IS_ENABLED(CONFIG_LOCKDEP)) > WARN_ON_ONCE(!lockdep_is_held(&some_lock)) > > This works during the compilation because the prototype of lockdep_is_held() > is declared. And since the IS_ENABLED() is resolved during compilation as well, > the conditional code is wiped out and therefore not linked. As a result the > linker doesn't even look for the definition of lockdep_is_held() and we don't > need to define an off case that would return a wrong assumption. > > Thanks. > Thank you for your explanation -- Best regards, Ridong