From nobody Sat Apr 18 19:10:24 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 910F5C433EF for ; Mon, 11 Jul 2022 21:16:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232025AbiGKVQ1 (ORCPT ); Mon, 11 Jul 2022 17:16:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36008 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231858AbiGKVQY (ORCPT ); Mon, 11 Jul 2022 17:16:24 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 8C45F80511 for ; Mon, 11 Jul 2022 14:16:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1657574182; 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=B17g9wAT+9shoXVHnJnHIlRvD72JVpKr/HdI9ugSZ80=; b=eVoBr/yoiV9Q9RvfxupDNxu9tGbVFK6wzolPkTCfKWcS8u1I1wfzOqshhdoHedHONfGwmZ +R/MHvphbzSwosyV0tiN+Kib+c3E75h8IsbYIw1e07/PcN1R67v5ant4upXYX/GziZHNo9 YFfOy58XCzkBlY+auV5YSRZpcA4Hnk0= 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-675-BymDG5gsMMiVt8p7M54asw-1; Mon, 11 Jul 2022 17:16:21 -0400 X-MC-Unique: BymDG5gsMMiVt8p7M54asw-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id A0D6F8032EA; Mon, 11 Jul 2022 21:16:20 +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 7F5212166B26; Mon, 11 Jul 2022 21:16:20 +0000 (UTC) From: Phil Auld To: linux-kernel@vger.kernel.org Cc: Thomas Gleixner , Peter Zijlstra , Valentin Schneider Subject: [PATCH v3 1/2] cpuhp: make target_store() a nop when target == state Date: Mon, 11 Jul 2022 17:16:18 -0400 Message-Id: <20220711211619.112854-2-pauld@redhat.com> In-Reply-To: <20220711211619.112854-1-pauld@redhat.com> References: <20220711211619.112854-1-pauld@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 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 --- kernel/cpu.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/cpu.c b/kernel/cpu.c index bbad5e375d3b..305694a2ca26 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 (st->target !=3D target) + st->target =3D target; out: unlock_device_hotplug(); return ret ? ret : count; --=20 2.31.1 From nobody Sat Apr 18 19:10:24 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 A276FC433EF for ; Mon, 11 Jul 2022 21:16:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232043AbiGKVQ3 (ORCPT ); Mon, 11 Jul 2022 17:16:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36002 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231998AbiGKVQZ (ORCPT ); Mon, 11 Jul 2022 17:16:25 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 187CE823B4 for ; Mon, 11 Jul 2022 14:16:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1657574184; 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=nLmRjFgRdRfGxyaNnmOGdO+qzhincW9I2IkPSw2Cgdg=; b=Fl6RNpIBiFQB9VeCNkImGO4mD96qhG3sTD6kr+ykKj8Egdgj9jIK9jJaW/3jvaHOhl/QnE MaGLioFv1WFyaIgbFu5eIROKgkJE+wCUnNfx9Q/poBAlJ0czNbSy+TwF4HCnQ9Pqq5qFap Qd3lG/k78RI8NCjFR2c9MObGSw5X3n8= 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-147-d3oeHARRP4iykw2aRydtAg-1; Mon, 11 Jul 2022 17:16:21 -0400 X-MC-Unique: d3oeHARRP4iykw2aRydtAg-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id CB191380451A; Mon, 11 Jul 2022 21:16:20 +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 A918D2166B26; Mon, 11 Jul 2022 21:16:20 +0000 (UTC) From: Phil Auld To: linux-kernel@vger.kernel.org Cc: Thomas Gleixner , Peter Zijlstra , Valentin Schneider Subject: [PATCH v3 2/2] cpuhp: Set cpuhp target for boot cpu Date: Mon, 11 Jul 2022 17:16:19 -0400 Message-Id: <20220711211619.112854-3-pauld@redhat.com> In-Reply-To: <20220711211619.112854-1-pauld@redhat.com> References: <20220711211619.112854-1-pauld@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 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. Set the target to match in boot_cpu_hotplug_init(). Signed-off-by: Phil Auld Reviewed-by: Valentin Schneider --- kernel/cpu.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/cpu.c b/kernel/cpu.c index 305694a2ca26..104f43a6f4ad 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