From nobody Fri Apr 3 05:33:36 2026 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 66D98C43217 for ; Thu, 17 Nov 2022 16:27:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240476AbiKQQ1h (ORCPT ); Thu, 17 Nov 2022 11:27:37 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35060 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240438AbiKQQ0j (ORCPT ); Thu, 17 Nov 2022 11:26:39 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6D35A17060 for ; Thu, 17 Nov 2022 08:23:35 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1668702214; h=from:from: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=GXoqsn/bnF/+v01p/YrE+6QGhTzDYbDEdVNXy7Olx1g=; b=W/yNaNQ1jMF1LLe8p0foPjTJLSURW4d3ZtValbFE/khH1OCngC5uDbA5/pymQtAX6oJ++W MDPn3LkmfOGlzvsxLl4ZnLjbTDTV8s4xmV/Q/2hVFlTNE7rifpvT4UZqO/5PV8fv2n0yBh zsiOw/55wo/lI4mI8MxRIEdBEgU22kw= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-259-ZSn0Yo_-NkCmpcH1TDBZdQ-1; Thu, 17 Nov 2022 11:23:33 -0500 X-MC-Unique: ZSn0Yo_-NkCmpcH1TDBZdQ-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 135D888434C; Thu, 17 Nov 2022 16:23:31 +0000 (UTC) Received: from pauld.bos.com (dhcp-17-237.bos.redhat.com [10.18.17.237]) by smtp.corp.redhat.com (Postfix) with ESMTP id D046135429; Thu, 17 Nov 2022 16:23:30 +0000 (UTC) From: Phil Auld To: linux-kernel@vger.kernel.org Cc: Thomas Gleixner , Peter Zijlstra , Valentin Schneider , Steven Price , Mark Rutland , Frederic Weisbecker , pauld@redhat.com Subject: [PATCH v5 1/2] cpuhp: Make target_store() a nop when target == state Date: Thu, 17 Nov 2022 11:23:28 -0500 Message-Id: <20221117162329.3164999-2-pauld@redhat.com> In-Reply-To: <20221117162329.3164999-1-pauld@redhat.com> References: <20221117162329.3164999-1-pauld@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Writing the current state back in hotplug/target calls cpu_down() which will set cpu dying even when it isn't and then nothing will ever clear it. A stress test that reads values and writes them back for all cpu device files in sysfs will trigger the BUG() in select_fallback_rq once all cpus are marked as dying. kernel/cpu.c::target_store() ... if (st->state < target) ret =3D cpu_up(dev->id, target); else ret =3D cpu_down(dev->id, target); cpu_down() -> cpu_set_state() bool bringup =3D st->state < target; ... if (cpu_dying(cpu) !=3D !bringup) set_cpu_dying(cpu, !bringup); Fix this by letting state=3D=3Dtarget fall through in the target_store() conditional. Also make sure st->target =3D=3D target in that case. Signed-off-by: Phil Auld Reviewed-by: Valentin Schneider Fixes: 757c989b9994 ("cpu/hotplug: Make target state writeable") Cc: Thomas Gleixner Cc: "Peter Zijlstra (Intel)" Cc: Steven Price Cc: Mark Rutland Cc: Frederic Weisbecker --- kernel/cpu.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/cpu.c b/kernel/cpu.c index bbad5e375d3b..979de993f853 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -2326,8 +2326,10 @@ static ssize_t target_store(struct device *dev, stru= ct device_attribute *attr, =20 if (st->state < target) ret =3D cpu_up(dev->id, target); - else + else if (st->state > target) ret =3D cpu_down(dev->id, target); + else if (WARN_ON(st->target !=3D target)) + st->target =3D target; out: unlock_device_hotplug(); return ret ? ret : count; --=20 2.31.1 From nobody Fri Apr 3 05:33:36 2026 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E91CBC4332F for ; Thu, 17 Nov 2022 16:27:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240613AbiKQQ1n (ORCPT ); Thu, 17 Nov 2022 11:27:43 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57174 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240456AbiKQQ0l (ORCPT ); Thu, 17 Nov 2022 11:26:41 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0622014023 for ; Thu, 17 Nov 2022 08:23:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1668702216; h=from:from: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=2WFPI0NFugsCul//0RfsqwViFOLqhD0XmwgH8bMY+Xk=; b=B5O6pngTS15MpjfnDSd7vyvx0B3ws6w67nyxwTVvhxBANsN/saSGzmGpRFtGLSZYHswVKu P7LJRTNK3NWZ9Sp6lmBuSIYY5tn+CZu5U97N5xSLbR9mcB/pvRAsqivwFZ3ANFG5jbXgho v4wlP5F6SNeiJr6KQVQqiCHgJE9nNYI= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-458-lX4sOq1TM_KTv2Fj2jL6bA-1; Thu, 17 Nov 2022 11:23:31 -0500 X-MC-Unique: lX4sOq1TM_KTv2Fj2jL6bA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 545EE3C11EAE; Thu, 17 Nov 2022 16:23:31 +0000 (UTC) Received: from pauld.bos.com (dhcp-17-237.bos.redhat.com [10.18.17.237]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1C09A35429; Thu, 17 Nov 2022 16:23:31 +0000 (UTC) From: Phil Auld To: linux-kernel@vger.kernel.org Cc: Thomas Gleixner , Peter Zijlstra , Valentin Schneider , Steven Price , Mark Rutland , Frederic Weisbecker , pauld@redhat.com Subject: [PATCH v5 2/2] cpuhp: Set cpuhp target for boot cpu Date: Thu, 17 Nov 2022 11:23:29 -0500 Message-Id: <20221117162329.3164999-3-pauld@redhat.com> In-Reply-To: <20221117162329.3164999-1-pauld@redhat.com> References: <20221117162329.3164999-1-pauld@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Since the boot cpu does not go through the hotplug process it ends up with state =3D=3D CPUHP_ONLINE but target =3D=3D CPUHP_OFFLINE. So set the target to match in boot_cpu_hotplug_init(). Signed-off-by: Phil Auld Reviewed-by: Valentin Schneider Cc: Thomas Gleixner Cc: "Peter Zijlstra (Intel)" Cc: Steven Price Cc: Mark Rutland Cc: Frederic Weisbecker --- kernel/cpu.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/cpu.c b/kernel/cpu.c index 979de993f853..3f704a8896b0 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -2690,6 +2690,7 @@ void __init boot_cpu_hotplug_init(void) cpumask_set_cpu(smp_processor_id(), &cpus_booted_once_mask); #endif this_cpu_write(cpuhp_state.state, CPUHP_ONLINE); + this_cpu_write(cpuhp_state.target, CPUHP_ONLINE); } =20 /* --=20 2.31.1