From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 93505C04AAF for ; Thu, 16 May 2019 14:21:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6A2102082E for ; Thu, 16 May 2019 14:21:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727109AbfEPOVY (ORCPT ); Thu, 16 May 2019 10:21:24 -0400 Received: from foss.arm.com ([217.140.101.70]:47414 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726687AbfEPOVY (ORCPT ); Thu, 16 May 2019 10:21:24 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 8268E1715; Thu, 16 May 2019 07:21:23 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2C1413F71E; Thu, 16 May 2019 07:21:22 -0700 (PDT) Date: Thu, 16 May 2019 15:21:19 +0100 From: Mark Rutland To: Mike Rapoport Cc: Christoph Hellwig , linux-kernel@vger.kernel.org, Steven Price , Andrew Morton , Will Deacon , Catalin Marinas Subject: Re: Bad virt_to_phys since commit 54c7a8916a887f35 Message-ID: <20190516142119.GD43059@lakrids.cambridge.arm.com> References: <20190516133820.GA43059@lakrids.cambridge.arm.com> <20190516134105.GB43059@lakrids.cambridge.arm.com> <20190516141314.GF19122@rapoport-lnx> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190516141314.GF19122@rapoport-lnx> User-Agent: Mutt/1.11.1+11 (2f07cb52) (2018-12-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 16, 2019 at 05:13:14PM +0300, Mike Rapoport wrote: > On Thu, May 16, 2019 at 02:41:06PM +0100, Mark Rutland wrote: > > On Thu, May 16, 2019 at 02:38:20PM +0100, Mark Rutland wrote: > > > Hi, > > > > > > Since commit: > > > > > > 54c7a8916a887f35 ("initramfs: free initrd memory if opening /initrd.image fails") > > > > Ugh, I dropped a paragarph here. > > > > Since that commit, I'm seeing a boot-time splat on arm64 when using > > CONFIG_DEBUG_VIRTUAL. I'm running an arm64 syzkaller instance, and this > > kills the VM, preventing further testing, which is unfortunate. > > > > Mark. > > > > > IIUC prior to that commit, we'd only attempt to free an intird if we had > > > one, whereas now we do so unconditionally. AFAICT, in this case > > > initrd_start has not been initialized (I'm not using an initrd or > > > initramfs on my system), so we end up trying virt_to_phys() on a bogus > > > VA in free_initrd_mem(). > > > > > > Any ideas on the right way to fix this? > > If I remember correctly, initrd_start would be 0 unless explicitly set by > the arch setup code, so something like this could work: > > diff --git a/init/initramfs.c b/init/initramfs.c > index 435a428c2af1..05fe60437796 100644 > --- a/init/initramfs.c > +++ b/init/initramfs.c > @@ -529,6 +529,9 @@ extern unsigned long __initramfs_size; > > void __weak free_initrd_mem(unsigned long start, unsigned long end) > { > + if (!start) > + return; > + > free_reserved_area((void *)start, (void *)end, POISON_FREE_INITMEM, > "initrd"); > } I think this should work, given Steven's patch checks the same thing. I don't have a preference as to which patch should be taken, so I'll leave that to Christoph. Thanks, Mark.