Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753302AbaBCROR (ORCPT ); Mon, 3 Feb 2014 12:14:17 -0500 Received: from relay3.sgi.com ([192.48.152.1]:49071 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752922AbaBCROP (ORCPT ); Mon, 3 Feb 2014 12:14:15 -0500 Date: Mon, 3 Feb 2014 11:14:12 -0600 From: Alex Thorlton To: Andrew Morton Cc: linux-kernel@vger.kernel.org, Oleg Nesterov , Gerald Schaefer , Martin Schwidefsky , Heiko Carstens , Christian Borntraeger , Paolo Bonzini , "Kirill A. Shutemov" , Mel Gorman , Rik van Riel , Ingo Molnar , Peter Zijlstra , Sasha Levin , linux390@de.ibm.com, linux-s390@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 1/3] Revert "thp: make MADV_HUGEPAGE check for mm->def_flags" Message-ID: <20140203171412.GA3034@sgi.com> References: <1391192628-113858-1-git-send-email-athorlton@sgi.com> <1391192628-113858-3-git-send-email-athorlton@sgi.com> <20140131145224.7f8efc67d882a2e1a89b0778@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140131145224.7f8efc67d882a2e1a89b0778@linux-foundation.org> 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 Fri, Jan 31, 2014 at 02:52:24PM -0800, Andrew Morton wrote: > On Fri, 31 Jan 2014 12:23:43 -0600 Alex Thorlton wrote: > > > This reverts commit 8e72033f2a489b6c98c4e3c7cc281b1afd6cb85cm, and adds > > 'm' is not a hex digit ;) My mistake! Sorry about that. > > in code to fix up any issues caused by the revert. > > > > The revert is necessary because hugepage_madvise would return -EINVAL > > when VM_NOHUGEPAGE is set, which will break subsequent chunks of this > > patch set. > > This is a bit skimpy. Why doesn't the patch re-break kvm-on-s390? > > it would be nice to have a lot more detail here, please. What was the > intent of 8e72033f2a48, how this patch retains 8e72033f2a48's behavior, > etc. I'm actually not too sure about this, off hand. I just know that we couldn't have it in there because of the check for VM_NOHUGEPAGE. The s390 guys approved the revert, as long as we added in the following piece: > > --- a/arch/s390/mm/pgtable.c > > +++ b/arch/s390/mm/pgtable.c > > @@ -504,6 +504,9 @@ static int gmap_connect_pgtable(unsigned long address, unsigned long segment, > > if (!pmd_present(*pmd) && > > __pte_alloc(mm, vma, pmd, vmaddr)) > > return -ENOMEM; > > + /* large pmds cannot yet be handled */ > > + if (pmd_large(*pmd)) > > + return -EFAULT; > > This bit wasn't in 8e72033f2a48. I added the fix-up code in with the revert, so that it would all be in one place; wasn't sure what the standard was for this sort of thing. If it's preferable to see this code in a separate patch, that's easy enough to do. I'll look into exactly what the original commit was intended to do, and get a better description of what's going on here. Let me know if I should split the two changes into separate patches. - Alex -- 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/