From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9E6882FE592; Fri, 6 Feb 2026 22:28:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770416936; cv=none; b=ordO3lJWaWAQ2TG863IgNVHDcLqMik+kWb+4lAaOOR9sWX0bS/sniM2wbZfy8RuPiytUZirbyh71kvMrvfB6lV0Fq/VKEnl2vUIQldOflfM9BfAccharTUAaygEMFLopjxQcIOYmA1DkP57uQtq9wY6tMejNrZWcseE6mhOM8o8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770416936; c=relaxed/simple; bh=rdLqwh1d0Cjcb0ou2UWhCKOuEt9xEUXrTNcdzePa7ZI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ip719gQQQ0N76yY8nVdUPZGjqMECqgGK3qDjyRFhq+yYMbm0A+QZfz4nibL+dCogpJcCXWgyhhvae8+9+Hv7VPTevGm1nN2cBal0UOzd2BJs9j+GFMtPGxhhiJNbkSru/IRyv2W1W3DYPnlkaVMFtYcC2NkL1fEJScF1oUa3Z2c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=P+fawaGG; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="P+fawaGG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D53B5C116C6; Fri, 6 Feb 2026 22:28:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770416936; bh=rdLqwh1d0Cjcb0ou2UWhCKOuEt9xEUXrTNcdzePa7ZI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=P+fawaGGwC+iH4a6HZt60i/wY3XrZ9RQeoNfcJFbsCgyXfJf+Oua+0sj2hVijifxa vaCCM4MeAKeTIo8fopvJEADSUvjeaUcoA3irW7m/OelMR+idvYkrXYrxoFCZgm79LF eLXp3fHZZybK88GJsKD7gwTX8H59rPCNIYB2SzlTOlCFJ+e55jfzfTWH5DHWZMifrf PhaEekHirs6u+whJQwcfanuu65IuqCD1eaqqT24apcwM9cRSFb3L6BRU8v+dhyZ1e+ cPs5g9Db/idnWmrVi6Hq9i7NS1duoJ2JVxOBtOoXffKhCz7OxlB+OvpCE9ssdrQvrA 647266cwyxoQg== Date: Fri, 6 Feb 2026 23:28:53 +0100 From: Frederic Weisbecker To: Waiman Long Cc: Chen Ridong , Tejun Heo , Johannes Weiner , Michal =?iso-8859-1?Q?Koutn=FD?= , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , Anna-Maria Behnsen , Thomas Gleixner , Shuah Khan , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH/for-next v4 2/4] cgroup/cpuset: Defer housekeeping_update() calls from CPU hotplug to workqueue Message-ID: References: <20260206203712.1989610-1-longman@redhat.com> <20260206203712.1989610-3-longman@redhat.com> Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260206203712.1989610-3-longman@redhat.com> Le Fri, Feb 06, 2026 at 03:37:10PM -0500, Waiman Long a écrit : > The update_isolation_cpumasks() function can be called either directly > from regular cpuset control file write with cpuset_full_lock() called > or via the CPU hotplug path with cpus_write_lock and cpuset_mutex held. > > As we are going to enable dynamic update to the nozh_full housekeeping > cpumask (HK_TYPE_KERNEL_NOISE) soon with the help of CPU hotplug, > allowing the CPU hotplug path to call into housekeeping_update() directly > from update_isolation_cpumasks() will likely cause deadlock. So we Why do we need to call housekeeping_update() from hotplug? I would expect it to be called only when cpuset control file are written since housekeeping cpumask don't deal with online CPUs but with possible CPUs. Thanks. -- Frederic Weisbecker SUSE Labs