From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f199.google.com (mail-pf0-f199.google.com [209.85.192.199]) by kanga.kvack.org (Postfix) with ESMTP id 19FD36B0351 for ; Fri, 24 Mar 2017 07:47:19 -0400 (EDT) Received: by mail-pf0-f199.google.com with SMTP id r89so69588pfi.1 for ; Fri, 24 Mar 2017 04:47:19 -0700 (PDT) Received: from mga01.intel.com (mga01.intel.com. [192.55.52.88]) by mx.google.com with ESMTPS id r76si1809307pfj.47.2017.03.24.04.47.14 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 24 Mar 2017 04:47:14 -0700 (PDT) Date: Fri, 24 Mar 2017 14:47:09 +0300 From: "Kirill A. Shutemov" Subject: Re: [x86/mm/gup] 2947ba054a [ 71.329069] kernel BUG at include/linux/pagemap.h:151! Message-ID: <20170324114709.pcytvyb3d6ajux33@black.fi.intel.com> References: <20170319225124.xodpqjldom6ceazz@wfg-t540p.sh.intel.com> <20170324102436.xltop6udkx5pg4oq@node.shutemov.name> <20170324105153.xvy5rcuawicqoanl@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170324105153.xvy5rcuawicqoanl@hirez.programming.kicks-ass.net> Sender: owner-linux-mm@kvack.org List-ID: To: Peter Zijlstra Cc: "Kirill A. Shutemov" , Ingo Molnar , x86@kernel.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Fengguang Wu , linux-kernel@vger.kernel.org, linux-mm@kvack.org, LKP , Linus Torvalds , "Aneesh Kumar K.V" On Fri, Mar 24, 2017 at 11:51:53AM +0100, Peter Zijlstra wrote: > On Fri, Mar 24, 2017 at 01:24:36PM +0300, Kirill A. Shutemov wrote: > > > I'm not sure what is the best way to fix this. > > Few options: > > - Drop the VM_BUG(); > > - Bump preempt count during __get_user_pages_fast(); > > - Use get_page() instead of page_cache_get_speculative() on x86. > > > > Any opinions? > > I think I'm in favour of the first; either remove or amend to include > irqs_disabled() or so. > > This in favour of keeping the variants of GUP down. Something like this? -------------------8<-----------------------