From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:36013 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753508AbcHQMyC (ORCPT ); Wed, 17 Aug 2016 08:54:02 -0400 Subject: Patch "arm64: Honor nosmp kernel command line option" has been added to the 4.7-stable tree To: suzuki.poulose@arm.com, catalin.marinas@arm.com, gregkh@linuxfoundation.org, james.morse@arm.com, mark.rutland@arm.com, will.deacon@arm.com Cc: , From: Date: Wed, 17 Aug 2016 14:54:03 +0200 Message-ID: <147143844387176@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled arm64: Honor nosmp kernel command line option to the 4.7-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: arm64-honor-nosmp-kernel-command-line-option.patch and it can be found in the queue-4.7 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From e75118a7b581b19b08282c7819c1ec6f68b91b79 Mon Sep 17 00:00:00 2001 From: Suzuki K Poulose Date: Thu, 21 Jul 2016 11:15:27 +0100 Subject: arm64: Honor nosmp kernel command line option From: Suzuki K Poulose commit e75118a7b581b19b08282c7819c1ec6f68b91b79 upstream. Passing "nosmp" should boot the kernel with a single processor, without provision to enable secondary CPUs even if they are present. "nosmp" is implemented by setting maxcpus=0. At the moment we still mark the secondary CPUs present even with nosmp, which allows the userspace to bring them up. This patch corrects the smp_prepare_cpus() to honor the maxcpus == 0. Commit 44dbcc93ab67145 ("arm64: Fix behavior of maxcpus=N") fixed the behavior for maxcpus >= 1, but broke maxcpus = 0. Fixes: 44dbcc93ab67 ("arm64: Fix behavior of maxcpus=N") Cc: Will Deacon Cc: James Morse Signed-off-by: Suzuki K Poulose Acked-by: Mark Rutland [catalin.marinas@arm.com: updated code comment] Signed-off-by: Catalin Marinas Signed-off-by: Greg Kroah-Hartman --- arch/arm64/kernel/smp.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -693,6 +693,13 @@ void __init smp_prepare_cpus(unsigned in smp_store_cpu_info(smp_processor_id()); /* + * If UP is mandated by "nosmp" (which implies "maxcpus=0"), don't set + * secondary CPUs present. + */ + if (max_cpus == 0) + return; + + /* * Initialise the present map (which describes the set of CPUs * actually populated at the present time) and release the * secondaries from the bootloader. Patches currently in stable-queue which might be from suzuki.poulose@arm.com are queue-4.7/arm64-fix-incorrect-per-cpu-usage-for-boot-cpu.patch queue-4.7/arm64-honor-nosmp-kernel-command-line-option.patch