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=-17.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=unavailable 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 D4FF7C433ED for ; Fri, 9 Apr 2021 12:45:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A4B00610E7 for ; Fri, 9 Apr 2021 12:45:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233470AbhDIMpO (ORCPT ); Fri, 9 Apr 2021 08:45:14 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:45492 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231402AbhDIMpN (ORCPT ); Fri, 9 Apr 2021 08:45:13 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1617972300; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=uvnPWZA5WYAbjq6DAmDLsT765wKi9L7F6ktZ4467iS8=; b=Nwd0ZamUCMirrinLrQO0eN3gULzqLnLIGWx06wGxC3IuElBCrYFmQCszk7KTvtdcBOUsbB BaXoUMcws2+G9AVgMYdjmIjZPRFy5Z8Lwn/IUHHMLFMutBo9QPKKgYIpfY9fcKE0NKio2n 0yc/GBadvgxJAlPjR4Yo4ZhnTx8xAaM= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-151-xe4MRLsANf-LYo9N6WjUpQ-1; Fri, 09 Apr 2021 08:44:53 -0400 X-MC-Unique: xe4MRLsANf-LYo9N6WjUpQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 81DA7107ACCD; Fri, 9 Apr 2021 12:44:51 +0000 (UTC) Received: from localhost (ovpn-12-59.pek2.redhat.com [10.72.12.59]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3A66660BE5; Fri, 9 Apr 2021 12:44:46 +0000 (UTC) Date: Fri, 9 Apr 2021 20:44:43 +0800 From: Baoquan He To: Lianbo Jiang Cc: linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org, platform-driver-x86@vger.kernel.org, x86@kernel.org, ardb@kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dvhart@infradead.org, andy@infradead.org, hpa@zytor.com, kexec@lists.infradead.org, dyoung@redhat.com Subject: Re: [PATCH] x86/efi: Do not release sub-1MB memory regions when the crashkernel option is specified Message-ID: <20210409124443.GA20513@MiWiFi-R3L-srv> References: <20210407140316.30210-1-lijiang@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210407140316.30210-1-lijiang@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: platform-driver-x86@vger.kernel.org On 04/07/21 at 10:03pm, Lianbo Jiang wrote: > Some sub-1MB memory regions may be reserved by EFI boot services, and the > memory regions will be released later in the efi_free_boot_services(). > > Currently, always reserve all sub-1MB memory regions when the crashkernel > option is specified, but unfortunately EFI boot services may have already > reserved some sub-1MB memory regions before the crash_reserve_low_1M() is > called, which makes that the crash_reserve_low_1M() only own the > remaining sub-1MB memory regions, not all sub-1MB memory regions, because, > subsequently EFI boot services will free its own sub-1MB memory regions. > Eventually, DMA will be able to allocate memory from the sub-1MB area and > cause the following error: > So this patch is fixing a problem found in crash utility. We ever met the similar issue, later fixed by always reserving low 1M in commit 6f599d84231fd27 ("x86/kdump: Always reserve the low 1M when the crashkernel option is specified"). Seems the commit is not fixing it completely. > crash> kmem -s |grep invalid > kmem: dma-kmalloc-512: slab: ffffd52c40001900 invalid freepointer: ffff9403c0067300 > kmem: dma-kmalloc-512: slab: ffffd52c40001900 invalid freepointer: ffff9403c0067300 > crash> vtop ffff9403c0067300 > VIRTUAL PHYSICAL > ffff9403c0067300 67300 --->The physical address falls into this range [0x0000000000063000-0x000000000008efff] > > kernel debugging log: > ... > [ 0.008927] memblock_reserve: [0x0000000000010000-0x0000000000013fff] efi_reserve_boot_services+0x85/0xd0 > [ 0.008930] memblock_reserve: [0x0000000000063000-0x000000000008efff] efi_reserve_boot_services+0x85/0xd0 > ... > [ 0.009425] memblock_reserve: [0x0000000000000000-0x00000000000fffff] crash_reserve_low_1M+0x2c/0x49 > ... > [ 0.010586] Zone ranges: > [ 0.010587] DMA [mem 0x0000000000001000-0x0000000000ffffff] > [ 0.010589] DMA32 [mem 0x0000000001000000-0x00000000ffffffff] > [ 0.010591] Normal [mem 0x0000000100000000-0x0000000c7fffffff] > [ 0.010593] Device empty > ... > [ 8.814894] __memblock_free_late: [0x0000000000063000-0x000000000008efff] efi_free_boot_services+0x14b/0x23b > [ 8.815793] __memblock_free_late: [0x0000000000010000-0x0000000000013fff] efi_free_boot_services+0x14b/0x23b In commit 6f599d84231fd27, we call crash_reserve_low_1M() to lock the whole low 1M area if crashkernel is specified in kernel cmdline. But earlier efi_reserve_boot_services() invokation will break the intention of the whole low 1M reserving. In efi_reserve_boot_services(), if any memory under low 1M hasn't been reserved, it will call memblock_reserve() to reserve it and leave it to efi_free_boot_services() to free. Hi Lianbo, Please correct me if I am wrong or anything is missed. IIUC, can we move efi_reserve_boot_services() after reserve_real_mode() to fix this bug? Or move reserve_real_mode() before efi_reserve_boot_services() since those real mode regions are all under 1M? Assume efi boot code/data won't rely on low 1M area any more at this moment. Thanks Baoquan > > Do not release sub-1MB memory regions even though they are reserved by > EFI boot services, so that always reserve all sub-1MB memory regions when > the crashkernel option is specified. > > Signed-off-by: Lianbo Jiang > --- > arch/x86/platform/efi/quirks.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c > index 67d93a243c35..637f932c4fd4 100644 > --- a/arch/x86/platform/efi/quirks.c > +++ b/arch/x86/platform/efi/quirks.c > @@ -18,6 +18,7 @@ > #include > #include > #include > +#include > > #define EFI_MIN_RESERVE 5120 > > @@ -303,6 +304,19 @@ void __init efi_arch_mem_reserve(phys_addr_t addr, u64 size) > */ > static __init bool can_free_region(u64 start, u64 size) > { > + /* > + * Some sub-1MB memory regions may be reserved by EFI boot > + * services, and these memory regions will be released later > + * in the efi_free_boot_services(). > + * > + * Do not release sub-1MB memory regions even though they are > + * reserved by EFI boot services, because, always reserve all > + * sub-1MB memory when the crashkernel option is specified. > + */ > + if (cmdline_find_option(boot_command_line, "crashkernel", NULL, 0) > 0 > + && (start + size < (1<<20))) > + return false; > + > if (start + size > __pa_symbol(_text) && start <= __pa_symbol(_end)) > return false; > > -- > 2.17.1 >