From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753878AbbKLIzd (ORCPT ); Thu, 12 Nov 2015 03:55:33 -0500 Received: from mail-wm0-f48.google.com ([74.125.82.48]:35202 "EHLO mail-wm0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753494AbbKLIzb (ORCPT ); Thu, 12 Nov 2015 03:55:31 -0500 Date: Thu, 12 Nov 2015 09:55:27 +0100 From: Ingo Molnar To: "Kirill A. Shutemov" Cc: "Kirill A. Shutemov" , Borislav Petkov , hpa@zytor.com, tglx@linutronix.de, mingo@redhat.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, x86@kernel.org, jgross@suse.com, konrad.wilk@oracle.com, elliott@hpe.com, boris.ostrovsky@oracle.com, Toshi Kani , Linus Torvalds Subject: Re: [PATCH] x86/mm: fix regression with huge pages on PAE Message-ID: <20151112085527.GB18963@gmail.com> References: <20151110123429.GE19187@pd.tnic> <20151110135303.GA11246@node.shutemov.name> <20151110144648.GG19187@pd.tnic> <20151110150713.GA11956@node.shutemov.name> <20151110170447.GH19187@pd.tnic> <20151111095101.GA22512@pd.tnic> <20151112074854.GA5376@gmail.com> <20151112075758.GA20702@node.shutemov.name> <20151112080059.GA6835@gmail.com> <20151112084616.EABFE19B@black.fi.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151112084616.EABFE19B@black.fi.intel.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Kirill A. Shutemov wrote: > > But, what problems do you expect with having a wider mask than its primary usage? > > If it's used for 32-bit values it will be truncated down safely. (But I have not > > tested it, so I might be missing some complication.) > > Yeah, I basically worry about non realized side effect. Such a worry is prudent, the best way would be to double check a disassembly of a before/after vmlinux and see in which functions they differ and why. We might have similar bugs elsewhere - silently fixed by such a change. Thanks, Ingo From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f44.google.com (mail-wm0-f44.google.com [74.125.82.44]) by kanga.kvack.org (Postfix) with ESMTP id 07BB86B0253 for ; Thu, 12 Nov 2015 03:55:32 -0500 (EST) Received: by wmww144 with SMTP id w144so190886824wmw.1 for ; Thu, 12 Nov 2015 00:55:31 -0800 (PST) Received: from mail-wm0-x22e.google.com (mail-wm0-x22e.google.com. [2a00:1450:400c:c09::22e]) by mx.google.com with ESMTPS id t19si18230504wme.67.2015.11.12.00.55.30 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 12 Nov 2015 00:55:31 -0800 (PST) Received: by wmec201 with SMTP id c201so81076591wme.1 for ; Thu, 12 Nov 2015 00:55:30 -0800 (PST) Date: Thu, 12 Nov 2015 09:55:27 +0100 From: Ingo Molnar Subject: Re: [PATCH] x86/mm: fix regression with huge pages on PAE Message-ID: <20151112085527.GB18963@gmail.com> References: <20151110123429.GE19187@pd.tnic> <20151110135303.GA11246@node.shutemov.name> <20151110144648.GG19187@pd.tnic> <20151110150713.GA11956@node.shutemov.name> <20151110170447.GH19187@pd.tnic> <20151111095101.GA22512@pd.tnic> <20151112074854.GA5376@gmail.com> <20151112075758.GA20702@node.shutemov.name> <20151112080059.GA6835@gmail.com> <20151112084616.EABFE19B@black.fi.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151112084616.EABFE19B@black.fi.intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: "Kirill A. Shutemov" Cc: "Kirill A. Shutemov" , Borislav Petkov , hpa@zytor.com, tglx@linutronix.de, mingo@redhat.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, x86@kernel.org, jgross@suse.com, konrad.wilk@oracle.com, elliott@hpe.com, boris.ostrovsky@oracle.com, Toshi Kani , Linus Torvalds * Kirill A. Shutemov wrote: > > But, what problems do you expect with having a wider mask than its primary usage? > > If it's used for 32-bit values it will be truncated down safely. (But I have not > > tested it, so I might be missing some complication.) > > Yeah, I basically worry about non realized side effect. Such a worry is prudent, the best way would be to double check a disassembly of a before/after vmlinux and see in which functions they differ and why. We might have similar bugs elsewhere - silently fixed by such a change. Thanks, Ingo -- 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