From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756663Ab3KFOSj (ORCPT ); Wed, 6 Nov 2013 09:18:39 -0500 Received: from [204.155.152.216] ([204.155.152.216]:45673 "EHLO shutemov.name" rhost-flags-FAIL-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1756588Ab3KFOSh (ORCPT ); Wed, 6 Nov 2013 09:18:37 -0500 Date: Wed, 6 Nov 2013 15:21:55 +0200 From: "Kirill A. Shutemov" To: Peter Zijlstra Cc: Andrew Morton , "Kirill A. Shutemov" , Ingo Molnar , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org Subject: Re: [PATCH] mm: create a separate slab for page->ptl allocation Message-ID: <20131106132155.GA22132@shutemov.name> References: <1382442839-7458-1-git-send-email-kirill.shutemov@linux.intel.com> <20131105150145.734a5dd5b5d455800ebfa0d3@linux-foundation.org> <20131105224217.GC20167@shutemov.name> <20131105155619.021f32eba1ca8f15a73ed4c9@linux-foundation.org> <20131105231310.GE20167@shutemov.name> <20131106093131.GU28601@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131106093131.GU28601@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 06, 2013 at 10:31:31AM +0100, Peter Zijlstra wrote: > On Wed, Nov 06, 2013 at 01:13:11AM +0200, Kirill A. Shutemov wrote: > > I would like to get rid of __ptlock_alloc()/__ptlock_free() too, but I > > don't see a way within C: we need to know sizeof(spinlock_t) on > > preprocessor stage. > > > > We can have a hack on kbuild level: write small helper program to find out > > sizeof(spinlock_t) before start building and turn it into define. > > But it's overkill from my POV. And cross-compilation will be a fun. > > Ah, I just remembered, we have such a thing! Great! > @@ -1354,7 +1356,7 @@ static inline bool ptlock_init(struct page *page) > * slab code uses page->slab_cache and page->first_page (for tail > * pages), which share storage with page->ptl. > */ > - VM_BUG_ON(page->ptl); > + VM_BUG_ON(*(unsigned long *)&page->ptl); Huh? Why not direct cast to unsigned long? VM_BUG_ON((unsigned long)page->ptl); Otherwise: Reviewed-by: Kirill A. Shutemov -- Kirill A. Shutemov