Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753312AbaDFGmL (ORCPT ); Sun, 6 Apr 2014 02:42:11 -0400 Received: from mail-wg0-f52.google.com ([74.125.82.52]:48129 "EHLO mail-wg0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751379AbaDFGmJ (ORCPT ); Sun, 6 Apr 2014 02:42:09 -0400 Message-ID: <5340F73A.6090600@colorfullife.com> Date: Sun, 06 Apr 2014 08:42:02 +0200 From: Manfred Spraul User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.3.0 MIME-Version: 1.0 To: KOSAKI Motohiro , Davidlohr Bueso CC: Andrew Morton , aswin@hp.com, LKML , "linux-mm@kvack.org" , Greg Thelen , Kamezawa Hiroyuki Subject: Re: [PATCH] ipc,shm: disable shmmax and shmall by default References: <1396235199.2507.2.camel@buesod1.americas.hpqcorp.net> <1396386062.25314.24.camel@buesod1.americas.hpqcorp.net> <20140401142947.927642a408d84df27d581e36@linux-foundation.org> <20140401144801.603c288674ab8f417b42a043@linux-foundation.org> <1396394931.25314.34.camel@buesod1.americas.hpqcorp.net> <1396484447.2953.1.camel@buesod1.americas.hpqcorp.net> <533DB03D.7010308@colorfullife.com> <1396554637.2550.11.camel@buesod1.americas.hpqcorp.net> <1396587632.2499.5.camel@buesod1.americas.hpqcorp.net> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 04/05/2014 08:24 PM, KOSAKI Motohiro wrote: > On Fri, Apr 4, 2014 at 1:00 AM, Davidlohr Bueso wrote: >> I don't think it makes much sense to set unlimited for both 0 and >> ULONG_MAX, that would probably just create even more confusion. I agree. Unlimited was INT_MAX since 0.99.10 and ULONG_MAX since 2.3.39 (with proper backward compatibility for user space). Adding a second value for unlimited just creates confusion. >> But then again, we shouldn't even care about breaking things with shmmax >> or shmall with 0 value, it just makes no sense from a user PoV. shmmax >> cannot be 0 unless there's an overflow, which voids any valid cases, and >> thus shmall cannot be 0 either as it would go against any values set for >> shmmax. I think it's safe to ignore this. > Agreed. > IMHO, until you find out any incompatibility issue of this, we don't > need the switch > because we can't make good workaround for that. I'd suggest to merge your patch > and see what happen. I disagree: - "shmctl(,IPC_INFO,&buf); if (my_memory_size > buf.shmmax) perror("change shmmax");" worked correctly since 0.99.10. I don't think that merging the patch and seeing what happens is the right approach. - setting shmmax by default to ULONG_MAX is the perfect workaround. What reasons are there against the one-line patch? > > -#define SHMMAX 0x2000000 /* max shared seg size (bytes) */ > +#define SHMMAX ULONG_MAX /* max shared seg size (bytes) */ > -- Manfred -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/