From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx126.postini.com [74.125.245.126]) by kanga.kvack.org (Postfix) with SMTP id 43BEF6B0088 for ; Wed, 22 May 2013 06:19:23 -0400 (EDT) Date: Wed, 22 May 2013 12:19:16 +0200 From: Peter Zijlstra Subject: Re: [PATCH v2 00/10] uaccess: better might_sleep/might_fault behavior Message-ID: <20130522101916.GM18810@twins.programming.kicks-ass.net> References: <201305221125.36284.arnd@arndb.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201305221125.36284.arnd@arndb.de> Sender: owner-linux-mm@kvack.org List-ID: To: Arnd Bergmann Cc: "Michael S. Tsirkin" , linux-kernel@vger.kernel.org, Catalin Marinas , Will Deacon , David Howells , Hirokazu Takata , Michal Simek , Koichi Yasutake , Benjamin Herrenschmidt , Paul Mackerras , Chris Metcalf , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, 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 On Wed, May 22, 2013 at 11:25:36AM +0200, Arnd Bergmann wrote: > Calling might_fault() for every __get_user/__put_user is rather expensive > because it turns what should be a single instruction (plus fixup) into an > external function call. We could hide it all behind CONFIG_DEBUG_ATOMIC_SLEEP just like might_sleep() is. I'm not sure there's a point to might_fault() when might_sleep() is a NOP. -- 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