Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752129AbaB1Lw2 (ORCPT ); Fri, 28 Feb 2014 06:52:28 -0500 Received: from e06smtp15.uk.ibm.com ([195.75.94.111]:53076 "EHLO e06smtp15.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751570AbaB1LwZ (ORCPT ); Fri, 28 Feb 2014 06:52:25 -0500 Message-ID: <53107872.7030904@de.ibm.com> Date: Fri, 28 Feb 2014 12:52:18 +0100 From: Christian Borntraeger User-Agent: Mozilla/5.0 (X11; Linux i686; rv:24.0) Gecko/20100101 Thunderbird/24.3.0 MIME-Version: 1.0 To: Alex Thorlton , linux-kernel@vger.kernel.org CC: Gerald Schaefer , Martin Schwidefsky , Heiko Carstens , Andrew Morton , Paolo Bonzini , "Kirill A. Shutemov" , Mel Gorman , Rik van Riel , Ingo Molnar , Peter Zijlstra , Andrea Arcangeli , Oleg Nesterov , "Eric W. Biederman" , Alexander Viro , linux390@de.ibm.com, linux-s390@vger.kernel.org, linux-mm@kvack.org, linux-api@vger.kernel.org Subject: Re: [PATCH 2/4] mm, s390: Ignore MADV_HUGEPAGE on s390 to prevent SIGSEGV in qemu References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14022811-0342-0000-0000-000007F60384 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 27/02/14 18:23, Alex Thorlton wrote: > As Christian pointed out, the recent 'Revert "thp: make MADV_HUGEPAGE > check for mm->def_flags"' breaks qemu, it does QEMU_MADV_HUGEPAGE for > all kvm pages but this doesn't work after s390_enable_sie/thp_split_mm. > > Paolo suggested that instead of failing on the call to madvise, we > simply ignore the call (return 0). > > Reported-by: Christian Borntraeger > Suggested-by: Paolo Bonzini > Suggested-by: Oleg Nesterov > Signed-off-by: Alex Thorlton > Cc: Gerald Schaefer > Cc: Martin Schwidefsky > Cc: Heiko Carstens > Cc: Christian Borntraeger > Cc: Andrew Morton > Cc: Paolo Bonzini > Cc: "Kirill A. Shutemov" > Cc: Mel Gorman > Cc: Rik van Riel > Cc: Ingo Molnar > Cc: Peter Zijlstra > Cc: Andrea Arcangeli > Cc: Oleg Nesterov > Cc: "Eric W. Biederman" > Cc: Alexander Viro > Cc: linux390@de.ibm.com > Cc: linux-s390@vger.kernel.org > Cc: linux-kernel@vger.kernel.org > Cc: linux-mm@kvack.org > Cc: linux-api@vger.kernel.org > > --- > mm/huge_memory.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index a4310a5..61d234d 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -1970,6 +1970,15 @@ int hugepage_madvise(struct vm_area_struct *vma, > { > switch (advice) { > case MADV_HUGEPAGE: > +#ifdef CONFIG_S390 > + /* > + * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390 > + * can't handle this properly after s390_enable_sie, so we simply > + * ignore the madvise to prevent qemu from causing a SIGSEGV. > + */ > + if (mm_has_pgste(vma->vm_mm)) > + return 0; > +#endif > /* > * Be somewhat over-protective like KSM for now! > */ > Tested-by: Christian Borntraeger -- 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/