From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 00FDB4F4D02 for ; Mon, 19 Oct 2026 13:09:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792415357; cv=none; b=Cq8pOZVAAFqs37qW8lfjQGkxsD5vul3QKTY9qrQapJMNoEs8i2rAAhgfno0+iXUf7YTNYDCtYsVfOAE6pHkJM9bOB0Xs4mpged4iOV6N1h8YOUnpzkOhNntO5ofPvttVXIpGc/3sOJjMfMx6M7vywx9gImwABM9AVtboAoJefvI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792415357; c=relaxed/simple; bh=BdfF0ifHxZW8BW7BBztOiGGGvadM8kv94TwgeRxhR9U=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=OeQzGEpbfQdwP+PH/fx58iTwEb4yzioLbAO0IBlLTgZjgeoUY75LclL39rXjLD2worNWNT+7NX1ThM/LxADlGBUJEOJf77o06lK+AMKmtCYR1TSWtzdT9QcWkVHLorhl0ULTdiknhNyrDb5SywTKHUKcl4WfXjwydCINsm6728o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=PWeaTYra; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="PWeaTYra" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 262B31F000C4; Mon, 19 Oct 2026 13:09:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792415355; bh=PVIpZ/CcS/sPol1gKct9BxnWhxMMYGLvx5dUYD56VGo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=PWeaTYraNSU0jfaIqwHk3gfobQ+2fgZP92xcoul56bzzLM0EVG75YR2ylrqzPnvPA nE6hQ+pD6uXXf9MMOTzJ3a3IgBHFMfpd588BBqYw4lOT8zWxcqS0ICTfFBRuqKUESt fulBclwtHPibb7HGkKNSSDAbLkGf4C3OM7+6osuJ4NuG9ZeC0NTG0gh22TUDouDyCX 4N1O4VG1aPY8a6w67npS9sw8eFasKZRLLqyxD+SoChVdPqSwA8hqUIhazMJC9BiyNt BbPByneI5orT5+Lcm2oKk5Rf0L9f8hRbYlFaCWianuhnHV664ioAdChqW/7VFeeUbB h6fRPj0oPN4Cg== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Marco Crivellari , Peter Zijlstra , Phil Auld , Thomas Gleixner , Waiman Long , "Paul E. McKenney" , Neeraj Upadhyay , Joel Fernandes , Boqun Feng , Uladzislau Rezki Subject: [RFC PATCH 04/49] rcu: Move CPUHP_AP_RCUTREE_DYING to post stop_machine() Date: Mon, 19 Oct 2026 15:08:11 +0200 Message-ID: <20261019130856.49711-5-frederic@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261019130856.49711-1-frederic@kernel.org> References: <20261019130856.49711-1-frederic@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Between CPUHP_TEARDOWN_CPU and CPUHP_AP_OFFLINE, stop_machine executes all the teardown callbacks while stopping all CPUs in the system. This doesn't mix-up well with running RT or isolated tasks. In order to transition smoothly from global stop_machine to finer grained synchronization between teardown callbacks and the other CPUs, a new stop machine post function has been introduced to be executed after the main one with IRQs still disabled while other CPUs can exit stop_machine(). Here RCU just does tracing with already proper handling of racy accesses. Move this teardown callback to post stop_machine() accordingly. Signed-off-by: Frederic Weisbecker --- kernel/cpu.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/cpu.c b/kernel/cpu.c index 4f3f0ae36893..f22afb213d6f 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -1275,7 +1275,7 @@ void clear_tasks_mm_cpumask(int cpu) static int take_cpu_down(void *_param) { struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state); - enum cpuhp_state target = max((int)st->target, CPUHP_AP_SCHED_STARTING); + enum cpuhp_state target = max((int)st->target, CPUHP_AP_RCUTREE_DYING); int err, cpu = smp_processor_id(); /* Ensure this CPU doesn't handle any more interrupts. */ @@ -1303,7 +1303,7 @@ static int take_cpu_down_post(void *_param) enum cpuhp_state target = max((int)st->target, CPUHP_AP_OFFLINE); int cpu = smp_processor_id(); - WARN_ON(st->state != CPUHP_AP_SCHED_STARTING); + WARN_ON(st->state != CPUHP_AP_RCUTREE_DYING); /* * Invoke the former CPU_DYING callbacks. DYING must not fail! */ -- 2.53.0