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 158CC357D14; Tue, 16 Jun 2026 15:33:45 +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=1781624026; cv=none; b=iOebUNmTbfnGbBEdQBg+CqRaJK0tZTliitdGEMNUlXsybQiWjjW+mcSnUoyf0NZoAeIXqYkLziPnFVzQYdkZENR8JxUEKkJIRxdvHlrGt2DnMsM5eWVtX/sAsTVqDFOuxyLlVKGu8yscnb+fQhpsjkEmmDaqTfMzE1KgTnY/r9o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781624026; c=relaxed/simple; bh=3Wl7aw1NMhBSn+S0QfdHQ4jSCuj0jhyvxIr25ghK2SE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=VSyZRWMmkYYrE1cS5LPaKwDipIs8vtu3nuSgiuq+v8fz9GgzaWpfvdWF1Gxi3GSj9KshjG6Lg4XcFkizXdMWxZJfagthM0FMMd6PVJNTd1GNdwZzFyFDv7eivcy5RI4NtzwXVIdIXKIk5qrfxAA/cdyRb/xR2lLzVK44z46dTMQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=k4ZvDgqL; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="k4ZvDgqL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2570C1F000E9; Tue, 16 Jun 2026 15:33:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1781624025; bh=a9mnk0o5gOghuskrYkxkrLnfY/5lVOxbo64dMuSfa3Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=k4ZvDgqLr46TfeeEXiiBSjAFCpHLN5/8aDPIjb/6THlLewoVrPtVk2phbq0sJO7eb FiUe+lqiJWyRk34tuKjI2j2dQL02oFpyYJ8fr6sGJaiJSUotfluq4Qv0MSd/h2iYJD MjqiTKzQhMPshANmrUgmGiO58AY7BpQxHnjqTGzM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Massimiliano Pellizzer , Sven Schnelle , Heiko Carstens , Alexander Gordeev Subject: [PATCH 7.0 258/378] s390: Remove GENERIC_LOCKBREAK Kconfig option Date: Tue, 16 Jun 2026 20:28:09 +0530 Message-ID: <20260616145123.693127672@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260616145109.744539446@linuxfoundation.org> References: <20260616145109.744539446@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: Heiko Carstens commit 1f57f68c4dd101e5e8ffc9ffa6428f45bcdd776a upstream. 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 Reviewed-by: Sven Schnelle Signed-off-by: Heiko Carstens Signed-off-by: Alexander Gordeev Signed-off-by: Greg Kroah-Hartman --- arch/s390/Kconfig | 3 --- 1 file changed, 3 deletions(-) --- 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