From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:58962 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751798AbdLUJgx (ORCPT ); Thu, 21 Dec 2017 04:36:53 -0500 Subject: Patch "ARM: Hide finish_arch_post_lock_switch() from modules" has been added to the 4.4-stable tree To: rostedt@goodmis.org, acme@redhat.com, alexander.shishkin@linux.intel.com, ard.biesheuvel@linaro.org, arnd@arndb.de, bp@suse.de, eranian@google.com, fweisbec@gmail.com, gregkh@linuxfoundation.org, jolsa@redhat.com, linux@armlinux.org.uk, linux@roeck-us.net, luto@amacapital.net, luto@kernel.org, mgorman@techsingularity.net, mingo@kernel.org, peterz@infradead.org, rmk+kernel@arm.linux.org.uk, tglx@linutronix.de, torvalds@linux-foundation.org, vincent.weaver@maine.edu Cc: , From: Date: Thu, 21 Dec 2017 10:36:42 +0100 Message-ID: <1513849002132230@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 ARM: Hide finish_arch_post_lock_switch() from modules to the 4.4-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: arm-hide-finish_arch_post_lock_switch-from-modules.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From ef0491ea17f8019821c7e9c8e801184ecf17f85a Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Fri, 13 May 2016 15:30:13 +0200 Subject: ARM: Hide finish_arch_post_lock_switch() from modules From: Steven Rostedt commit ef0491ea17f8019821c7e9c8e801184ecf17f85a upstream. The introduction of switch_mm_irqs_off() brought back an old bug regarding the use of preempt_enable_no_resched: As part of: 62b94a08da1b ("sched/preempt: Take away preempt_enable_no_resched() from modules") the definition of preempt_enable_no_resched() is only available in built-in code, not in loadable modules, so we can't generally use it from header files. However, the ARM version of finish_arch_post_lock_switch() calls preempt_enable_no_resched() and is defined as a static inline function in asm/mmu_context.h. This in turn means we cannot include asm/mmu_context.h from modules. With today's tip tree, asm/mmu_context.h gets included from linux/mmu_context.h, which is normally the exact pattern one would expect, but unfortunately, linux/mmu_context.h can be included from the vhost driver that is a loadable module, now causing this compile time error with modular configs: In file included from ../include/linux/mmu_context.h:4:0, from ../drivers/vhost/vhost.c:18: ../arch/arm/include/asm/mmu_context.h: In function 'finish_arch_post_lock_switch': ../arch/arm/include/asm/mmu_context.h:88:3: error: implicit declaration of function 'preempt_enable_no_resched' [-Werror=implicit-function-declaration] preempt_enable_no_resched(); Andy already tried to fix the bug by including linux/preempt.h from asm/mmu_context.h, but that didn't help. Arnd suggested reordering the header files, which wasn't popular, so let's use this workaround instead: The finish_arch_post_lock_switch() definition is now also hidden inside of #ifdef MODULE, so we don't see anything referencing preempt_enable_no_resched() from a header file. I've built a few hundred randconfig kernels with this, and did not see any new problems. Tested-by: Guenter Roeck Signed-off-by: Steven Rostedt Signed-off-by: Arnd Bergmann Acked-by: Russell King Cc: Alexander Shishkin Cc: Andy Lutomirski Cc: Andy Lutomirski Cc: Ard Biesheuvel Cc: Arnaldo Carvalho de Melo Cc: Borislav Petkov Cc: Frederic Weisbecker Cc: Jiri Olsa Cc: Linus Torvalds Cc: Mel Gorman Cc: Peter Zijlstra Cc: Russell King - ARM Linux Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Cc: linux-arm-kernel@lists.infradead.org Fixes: f98db6013c55 ("sched/core: Add switch_mm_irqs_off() and use it in the scheduler") Link: http://lkml.kernel.org/r/1463146234-161304-1-git-send-email-arnd@arndb.de Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- arch/arm/include/asm/mmu_context.h | 2 ++ 1 file changed, 2 insertions(+) --- a/arch/arm/include/asm/mmu_context.h +++ b/arch/arm/include/asm/mmu_context.h @@ -61,6 +61,7 @@ static inline void check_and_switch_cont cpu_switch_mm(mm->pgd, mm); } +#ifndef MODULE #define finish_arch_post_lock_switch \ finish_arch_post_lock_switch static inline void finish_arch_post_lock_switch(void) @@ -82,6 +83,7 @@ static inline void finish_arch_post_lock preempt_enable_no_resched(); } } +#endif /* !MODULE */ #endif /* CONFIG_MMU */ Patches currently in stable-queue which might be from rostedt@goodmis.org are queue-4.4/arm-hide-finish_arch_post_lock_switch-from-modules.patch