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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 EB0EDC2F441 for ; Mon, 21 Jan 2019 15:53:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C40F820879 for ; Mon, 21 Jan 2019 15:53:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730597AbfAUPxc (ORCPT ); Mon, 21 Jan 2019 10:53:32 -0500 Received: from foss.arm.com ([217.140.101.70]:37738 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729712AbfAUPxa (ORCPT ); Mon, 21 Jan 2019 10:53:30 -0500 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 CF864EBD; Mon, 21 Jan 2019 07:53:29 -0800 (PST) Received: from [10.1.196.75] (e110467-lin.cambridge.arm.com [10.1.196.75]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C398E3F5C1; Mon, 21 Jan 2019 07:53:26 -0800 (PST) Subject: Re: kmemleak panic To: Rob Herring , Catalin Marinas , Mike Rapoport Cc: Marc Gonzalez , Frank Rowand , Marek Szyprowski , Bjorn Andersson , Mark Rutland , Arnd Bergmann , Ard Biesheuvel , Oscar Salvador , Wei Yang , Michal Hocko , Andrew Morton , Linus Torvalds , Sri Krishna chowdary , Qian Cai , LKML References: <20190118143434.GE118707@arrakis.emea.arm.com> <20190119132832.GA29881@MBP.local> <6579db26-10ac-3fbf-1998-5b937a38f202@free.fr> <20190121143704.GE29504@arrakis.emea.arm.com> From: Robin Murphy Message-ID: <0cecfda4-e2c3-9282-12b1-fbe300708c72@arm.com> Date: Mon, 21 Jan 2019 15:53:25 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 21/01/2019 15:42, Rob Herring wrote: > +Mike Rapoport > > On Mon, Jan 21, 2019 at 8:37 AM Catalin Marinas wrote: >> >> On Mon, Jan 21, 2019 at 07:35:11AM -0600, Rob Herring wrote: >>> On Mon, Jan 21, 2019 at 6:19 AM Robin Murphy wrote: >>>> >>>> On 21/01/2019 11:57, Marc Gonzalez wrote: >>>> [...] >>>>> # echo dump=0xffffffc021e00000 > /sys/kernel/debug/kmemleak >>>>> kmemleak: Object 0xffffffc021e00000 (size 2097152): >>>>> kmemleak: comm "swapper/0", pid 0, jiffies 4294892296 >>>>> kmemleak: min_count = 0 >>>>> kmemleak: count = 0 >>>>> kmemleak: flags = 0x1 >>>>> kmemleak: checksum = 0 >>>>> kmemleak: backtrace: >>>>> kmemleak_alloc_phys+0x48/0x60 >>>>> memblock_alloc_range_nid+0x8c/0xa4 >>>>> memblock_alloc_base_nid+0x4c/0x60 >>>>> __memblock_alloc_base+0x3c/0x4c >>>>> early_init_dt_alloc_reserved_memory_arch+0x54/0xa4 >>>>> fdt_init_reserved_mem+0x308/0x3ec >>>>> early_init_fdt_scan_reserved_mem+0x88/0xb0 >>>>> arm64_memblock_init+0x1dc/0x254 >>>>> setup_arch+0x1c8/0x4ec >>>>> start_kernel+0x84/0x44c >>>>> 0xffffffffffffffff >>>> >>>> OK, so via the __va(phys) call in kmemleak_alloc_phys(), you end up with >>>> the linear map address of a no-map reservation, which unsurprisingly >>>> turns out not to be mapped. Is there a way to tell kmemleak that it >>>> can't scan within a particular object? >>> >>> There was this patch posted[1]. I never got a reply, so it hasn't been applied. >>> >>> https://patchwork.ozlabs.org/patch/995367/ >> >> Thanks Rob, I wasn't aware of this patch (or I just missed it at the >> time). >> >> I wonder whether kmemleak should simply remove ranges passed to >> memblock_remove(), or at least mark them as no-scan. > > Seems reasonable to me, but of course that impacts a lot of other > cases. Maybe Mike R has some thoughts? In particular, might that risk crippling kmemleak on EFI arm64 EFI, where we memblock_remove() the entire physical address space (but then rebuild the memblock list from scratch)? FWIW, from the reserved-memory angle I think that patch looks reasonable as-is (modulo perhaps a kmemleak_no_scan_phys() wrapper for API symmetry). MEMBLOCK_NOMAP is already a massive pain in the bum and I'd really rather not introduce any more usage of it if at all possible. Robin.