From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (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 E2B863D3CF5; Mon, 8 Jun 2026 17:05:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.163.158.5 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780938351; cv=none; b=OuY12tqnljYhoLNNYQ9Dk7qy6uuBQ/rgNG+YpUVI987yen9bMf03XL0j2m9lXpqyjl5giGDGWlLQbOUmWbikVyt3DVBZjL0PihBO6m0FCEEMoBQ4fm9hmcuwt2x39Jt06I0zqsrfzGzdSMuTuzE4UGbjFvKmlDepNYgwr8dmjog= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780938351; c=relaxed/simple; bh=fHMkAqPbx3llu2uvRDBK6cQtwTSzaYaOaMMk+4uo0AE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=qNBEFij82KlV7042VfLJTtoI7X/JxeAv83WcMn8+vPE2chgkNFtpZpApRK3Lxm3u3ADr8vdfAqXWWRpuCMte/S+NTfRbndJgF+aYoiHqXhqtz28+RKJNQ2spWd/qJtmrw3xraBw7F9tRv9DAd01VvqnpGE0VMMV8sNndyb/zHKY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com; spf=pass smtp.mailfrom=linux.ibm.com; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b=epAnTVy9; arc=none smtp.client-ip=148.163.158.5 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b="epAnTVy9" Received: from pps.filterd (m0360072.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 6586dFpm1992204; Mon, 8 Jun 2026 17:05:41 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-type:date:from:in-reply-to:message-id:mime-version :references:subject:to; s=pp1; bh=eUCzFhuOmhKm27Eu6GG8hharLP+BP/ A1JQ6K+nsJA/U=; b=epAnTVy9ypqJXAYIZ3mAtNTdbuCE4RIZBgS9P9k8qayqq0 iQcuhkfKpm9E/2q5b24KRIyvU4tKT5tkOQAJIy3PPX5eg4bj4pE9UY3fOYxu5+2/ HsurXcLeSNCOxgTyfw6nm9A/c2c1WUDlwnxNImq4YGnQAYke4veWmG6V3max7EuO AMEWVaGtst6drcWae36Dx1sDB5XFCvlexKHJhqMuHy8b5UUvw44b7KKVfAXOIumx 1CJVTBA+KbVZxqdz8FDd4TMrgX0FcDgHKMQzBhBm76MiQfjAQuU1OJ1BCJohcHfM oACtW7TjbGPC6ooxx1Fl0S0djJ+tC5KR1onTucLQ== Received: from ppma22.wdc07v.mail.ibm.com (5c.69.3da9.ip4.static.sl-reverse.com [169.61.105.92]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4emb6sr8xp-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 08 Jun 2026 17:05:41 +0000 (GMT) Received: from pps.filterd (ppma22.wdc07v.mail.ibm.com [127.0.0.1]) by ppma22.wdc07v.mail.ibm.com (8.18.1.7/8.18.1.7) with ESMTP id 658H4dmK020808; Mon, 8 Jun 2026 17:05:41 GMT Received: from smtprelay07.fra02v.mail.ibm.com ([9.218.2.229]) by ppma22.wdc07v.mail.ibm.com (PPS) with ESMTPS id 4emx8vxdkc-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 08 Jun 2026 17:05:40 +0000 (GMT) Received: from smtpav04.fra02v.mail.ibm.com (smtpav04.fra02v.mail.ibm.com [10.20.54.103]) by smtprelay07.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 658H5bSH45482328 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 8 Jun 2026 17:05:37 GMT Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 33A8F2004B; Mon, 8 Jun 2026 17:05:37 +0000 (GMT) Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 1304120043; Mon, 8 Jun 2026 17:05:37 +0000 (GMT) Received: from li-008a6a4c-3549-11b2-a85c-c5cc2836eea2.ibm.com (unknown [9.224.92.206]) by smtpav04.fra02v.mail.ibm.com (Postfix) with ESMTPS; Mon, 8 Jun 2026 17:05:37 +0000 (GMT) Date: Mon, 8 Jun 2026 19:05:35 +0200 From: Alexander Gordeev To: Heiko Carstens Cc: Sven Schnelle , Vasily Gorbik , Christian Borntraeger , Massimiliano Pellizzer , Peter Zijlstra , linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org Subject: Re: [PATCH] s390: Remove GENERIC_LOCKBREAK Kconfig option Message-ID: <1c7ef477-d57d-4fd8-a51a-05829095a2da-agordeev@linux.ibm.com> References: <20260605153206.2397521-1-hca@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260605153206.2397521-1-hca@linux.ibm.com> X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: aypBiSwLYnvZncHzBvymg-xl1lC1ZA6P X-Proofpoint-GUID: aypBiSwLYnvZncHzBvymg-xl1lC1ZA6P X-Authority-Analysis: v=2.4 cv=ZbEt8MVA c=1 sm=1 tr=0 ts=6a26f665 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=kj9zAlcOel0A:10 a=FelO9ux0wxsA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VwQbUJbxAAAA:8 a=DfNHnWVPAAAA:8 a=VnNF1IyMAAAA:8 a=8PwEbw_DHVNOmaeoEiAA:9 a=CjuIK1q_8ugA:10 a=rjTVMONInIDnV1a_A2c_:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNjA4MDE1OCBTYWx0ZWRfXyobYzCfrmjMw RPavBgjm+FSEAN8XzuTkqYX2wsXinpjdUw/Zq23BJQeHX1njmLHJ3i6OH7Ri2W/cEFWdgv0rVdN LKFESY0lzsQbj89oKsxSo8LQPPjQVaWHt9gUjWHqcx3x2pggxyPE8zweBX52xBkp5+4bW0yQLrQ ug49C5R8qtIbj8li1XV80STGHkhmGzjLbIe6nCEIly88sGMGXdLsZwceuD/sllg/Hh1342wlNwW I9lv3cq0L6gLx/CXTQCG+vGiE1gwHBRvR1pGpOM+NZqqOY+Vgxfz0+BH1jxwAQwwhk25GQl0Yhd i7k6bOXkPht/743sQgC3kMSCTipGO+lWtJ7vvuvKBVMLOl3U1A5ziWMvDvHW8Pnh+/e/v48OYZe 1fk4BkcPgAQ0rWTSUHbPofAG66nPvh46NSAXwe9cZoxn/6zeI/SvpMVsQF8on0SLnuUOTMbU16Y zWEUFZ/nmMbWA21ODfA== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.125,FMLib:17.12.100.49 definitions=2026-06-08_04,2026-06-05_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 impostorscore=0 malwarescore=0 lowpriorityscore=0 clxscore=1011 adultscore=0 spamscore=0 priorityscore=1501 bulkscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605210000 definitions=main-2606080158 On Fri, Jun 05, 2026 at 05:32:06PM +0200, Heiko Carstens wrote: > s390 selects GENERIC_LOCKBREAK if PREEMPT is enabled. Reason is a historic > 18 years old commit [1] which fixed a compile error for PREEMPT enabled > kernels. Back than only PREEMPT_NONE and PREEMPT_VOLUNTARY kernels were > considered to be important for s390. PREEMPT should "just work". > > However, since recently PREEMPT is always enabled [2], which also causes > GENERIC_LOCKBREAK to be always enabled. For some workloads this leads to > massive performance degradation; e.g. a simple kernel compile on machines > with many CPUs may take up to four times longer. > > To fix this just remove the GENERIC_LOCKBREAK from s390's Kconfig, since > the compile error from 18 years ago does not exist anymore. > > [1] commit b6b40c532a36 ("[S390] Define GENERIC_LOCKBREAK.") > [2] commit 7dadeaa6e851 ("sched: Further restrict the preemption modes") > > Cc: stable@vger.kernel.org > Reported-by: Massimiliano Pellizzer > Signed-off-by: Heiko Carstens > --- > arch/s390/Kconfig | 3 --- > 1 file changed, 3 deletions(-) > > diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig > index ecbcbb781e40..9921a3772bf7 100644 > --- a/arch/s390/Kconfig > +++ b/arch/s390/Kconfig > @@ -29,9 +29,6 @@ config GENERIC_BUG > config GENERIC_BUG_RELATIVE_POINTERS > def_bool y > > -config GENERIC_LOCKBREAK > - def_bool y if PREEMPTION > - > config AUDIT_ARCH > def_bool y Applied, thanks!