From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752643AbdDCK4v (ORCPT ); Mon, 3 Apr 2017 06:56:51 -0400 Received: from foss.arm.com ([217.140.101.70]:57494 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751515AbdDCK4u (ORCPT ); Mon, 3 Apr 2017 06:56:50 -0400 Date: Mon, 3 Apr 2017 11:56:29 +0100 From: Mark Rutland To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, will.deacon@arm.com, catalin.marinas@arm.com, punit.agrawal@arm.com Subject: Re: Bad page state splats on arm64, v4.11-rc{3,4} Message-ID: <20170403105629.GB18905@leverpostej> References: <20170331175845.GE6488@leverpostej> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170331175845.GE6488@leverpostej> 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, Mar 31, 2017 at 06:58:45PM +0100, Mark Rutland wrote: > Hi, > > I'm seeing intermittent bad page state splats on arm64 with 4.11-rc3 and > v4.11-rc4. I have not tested earlier kernels, or other architectures. > > So far, it looks like the flags are always bad in the same > way: > > bad because of flags: 0x80(waiters) > > ... though I don't know if that's definitely the case for splat 4, the > BUG at mm/page_alloc.c:800. > > I see this in QEMU VMs launched by Syzkaller, triggering once every few > hours. So far, I have not been able to reproduce the issue in any other > way (including using syz-repro). It looks like this may be an issue with the arm64 HUGETLB code. I wasn't able to trigger the issue over the weekend on a kernel with HUGETLBFS disabled. There are known issues with our handling of contiguous entries, and this might be an artefact of that. I'll see if I can narrow this down any further. Thanks, Mark.