From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754208AbdBTQMD (ORCPT ); Mon, 20 Feb 2017 11:12:03 -0500 Received: from mx2.suse.de ([195.135.220.15]:35099 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753434AbdBTQMB (ORCPT ); Mon, 20 Feb 2017 11:12:01 -0500 Date: Mon, 20 Feb 2017 17:11:58 +0100 From: Michal Hocko To: Davidlohr Bueso Cc: akpm@linux-foundation.org, manfred@colorfullife.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Davidlohr Bueso Subject: Re: [PATCH 4/4] mm,hugetlb: compute page_size_log properly Message-ID: <20170220161157.GO2431@dhcp22.suse.cz> References: <1486673582-6979-1-git-send-email-dave@stgolabs.net> <1486673582-6979-5-git-send-email-dave@stgolabs.net> <20170210102044.GA10054@dhcp22.suse.cz> <20170210165111.GB2392@linux-80c1.suse> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170210165111.GB2392@linux-80c1.suse> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Sorry for a late reply, I wasn't online last week On Fri 10-02-17 08:51:11, Davidlohr Bueso wrote: > On Fri, 10 Feb 2017, Michal Hocko wrote: > > > On Thu 09-02-17 12:53:02, Davidlohr Bueso wrote: > > > The SHM_HUGE_* stuff was introduced in: > > > > > > 42d7395feb5 (mm: support more pagesizes for MAP_HUGETLB/SHM_HUGETLB) > > > > > > It unnecessarily adds another layer, specific to sysv shm, without > > > anything special about it: the macros are identical to the MAP_HUGE_* > > > stuff, which in turn does correctly describe the hugepage subsystem. > > > > > > One example of the problems with extra layers what this patch fixes: > > > mmap_pgoff() should never be using SHM_HUGE_* logic. It is obviously > > > harmless but it would still be grand to get rid of it -- although > > > now in the manpages I don't see that happening. > > > > Can we just drop SHM_HUGE_MASK altogether? It is not exported in uapi > > headers AFAICS. > > Yeah that was my original idea, however I noticed that shmget.2 mentions > kernel internals as part of SHM_HUGE_{2MB,1GB}, ie: SHM_HUGE_SHIFT. So > dropping _MASK doesn't make sense if we are going to keep _SHIFT. I am not sure I understand. $ git grep SHM_HUGE_ include/uapi/ $ So there doesn't seem to be any user visible constant. The man page mentiones is but I do not really see how is the userspace supposed to use it. -- Michal Hocko SUSE Labs