From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx146.postini.com [74.125.245.146]) by kanga.kvack.org (Postfix) with SMTP id 5AD4F6B0033 for ; Thu, 16 May 2013 07:09:09 -0400 (EDT) Date: Thu, 16 May 2013 14:07:33 +0300 From: "Michael S. Tsirkin" Subject: [PATCH v2 00/10] uaccess: better might_sleep/might_fault behavior Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: owner-linux-mm@kvack.org List-ID: To: linux-kernel@vger.kernel.org Cc: Catalin Marinas , Will Deacon , David Howells , Hirokazu Takata , Michal Simek , Koichi Yasutake , Benjamin Herrenschmidt , Paul Mackerras , Chris Metcalf , Thomas Gleixner , Ingo Molnar , Peter Zijlstra , "H. Peter Anvin" , x86@kernel.org, Arnd Bergmann , linux-arm-kernel@lists.infradead.org, linux-m32r@ml.linux-m32r.org, linux-m32r-ja@ml.linux-m32r.org, microblaze-uclinux@itee.uq.edu.au, linux-am33-list@redhat.com, linuxppc-dev@lists.ozlabs.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, kvm@vger.kernel.org This improves the might_fault annotations used by uaccess routines: 1. The only reason uaccess routines might sleep is if they fault. Make this explicit for all architectures. 2. Accesses (e.g through socket ops) to kernel memory with KERNEL_DS like net/sunrpc does will never sleep. Remove an unconditinal might_sleep in the inline might_fault in kernel.h (used when PROVE_LOCKING is not set). 3. Accesses with pagefault_disable return EFAULT but won't cause caller to sleep. Check for that and avoid might_sleep when PROVE_LOCKING is set. I'd like these changes to go in for the benefit of the vhost driver where we want to call socket ops under a spinlock, and fall back on slower thread handler on error. Please review, and consider for 3.11. If the changes look good, what's the best way to merge them? Maybe core/locking makes sense? Note on arch code updates: I tested x86_64 code. Other architectures were build-tested. I don't have cross-build environment for arm64, tile, microblaze and mn10300 architectures. The changes look safe enough but would appreciate review/acks from arch maintainers. Version 1 of this change was titled x86: uaccess s/might_sleep/might_fault/ Changes from v1: add more architectures fix might_fault() scheduling differently depending on CONFIG_PROVE_LOCKING, as suggested by Ingo Michael S. Tsirkin (10): asm-generic: uaccess s/might_sleep/might_fault/ arm64: uaccess s/might_sleep/might_fault/ frv: uaccess s/might_sleep/might_fault/ m32r: uaccess s/might_sleep/might_fault/ microblaze: uaccess s/might_sleep/might_fault/ mn10300: uaccess s/might_sleep/might_fault/ powerpc: uaccess s/might_sleep/might_fault/ tile: uaccess s/might_sleep/might_fault/ x86: uaccess s/might_sleep/might_fault/ kernel: might_fault does not imply might_sleep arch/arm64/include/asm/uaccess.h | 4 ++-- arch/frv/include/asm/uaccess.h | 4 ++-- arch/m32r/include/asm/uaccess.h | 12 ++++++------ arch/microblaze/include/asm/uaccess.h | 6 +++--- arch/mn10300/include/asm/uaccess.h | 4 ++-- arch/powerpc/include/asm/uaccess.h | 16 ++++++++-------- arch/tile/include/asm/uaccess.h | 2 +- arch/x86/include/asm/uaccess_64.h | 2 +- include/asm-generic/uaccess.h | 10 +++++----- include/linux/kernel.h | 1 - mm/memory.c | 14 +++++++++----- 11 files changed, 39 insertions(+), 36 deletions(-) Thanks, -- MST -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org