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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,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 370FDC28CC5 for ; Wed, 5 Jun 2019 16:29:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 13EB620866 for ; Wed, 5 Jun 2019 16:29:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728651AbfFEQ31 (ORCPT ); Wed, 5 Jun 2019 12:29:27 -0400 Received: from foss.arm.com ([217.140.101.70]:34516 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726421AbfFEQ30 (ORCPT ); Wed, 5 Jun 2019 12:29:26 -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 1DFE2374; Wed, 5 Jun 2019 09:29:26 -0700 (PDT) Received: from [10.1.196.105] (eglon.cambridge.arm.com [10.1.196.105]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0FBED3F5AF; Wed, 5 Jun 2019 09:29:22 -0700 (PDT) Subject: Re: [PATCH 1/4] x86: kdump: move reserve_crashkernel_low() into kexec_core.c To: Chen Zhou Cc: catalin.marinas@arm.com, will.deacon@arm.com, akpm@linux-foundation.org, ard.biesheuvel@linaro.org, rppt@linux.ibm.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, ebiederm@xmission.com, horms@verge.net.au, takahiro.akashi@linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-mm@kvack.org, wangkefeng.wang@huawei.com References: <20190507035058.63992-1-chenzhou10@huawei.com> <20190507035058.63992-2-chenzhou10@huawei.com> From: James Morse Message-ID: <6585f047-063c-6d6c-4967-1d8a472f30f4@arm.com> Date: Wed, 5 Jun 2019 17:29:21 +0100 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <20190507035058.63992-2-chenzhou10@huawei.com> Content-Type: text/plain; charset=utf-8 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 Hello, On 07/05/2019 04:50, Chen Zhou wrote: > In preparation for supporting reserving crashkernel above 4G > in arm64 as x86_64 does, move reserve_crashkernel_low() into > kexec/kexec_core.c. > diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c > index 905dae8..9ee33b6 100644 > --- a/arch/x86/kernel/setup.c > +++ b/arch/x86/kernel/setup.c > @@ -463,59 +460,6 @@ static void __init memblock_x86_reserve_range_setup_data(void) > # define CRASH_ADDR_HIGH_MAX MAXMEM > #endif > > -static int __init reserve_crashkernel_low(void) > -{ > -#ifdef CONFIG_X86_64 The behaviour of this #ifdef has disappeared, won't 32bit x86 now try and reserve a chunk of unnecessary 'low' memory? [...] > @@ -579,9 +523,13 @@ static void __init reserve_crashkernel(void) > return; > } > > - if (crash_base >= (1ULL << 32) && reserve_crashkernel_low()) { > - memblock_free(crash_base, crash_size); > - return; > + if (crash_base >= (1ULL << 32)) { > + if (reserve_crashkernel_low()) { > + memblock_free(crash_base, crash_size); > + return; > + } > + > + insert_resource(&iomem_resource, &crashk_low_res); Previously reserve_crashkernel_low() was #ifdefed to do nothing if !CONFIG_X86_64, I don't see how 32bit is skipping this reservation... > } > > pr_info("Reserving %ldMB of memory at %ldMB for crashkernel (System RAM: %ldMB)\n", > diff --git a/include/linux/kexec.h b/include/linux/kexec.h > index b9b1bc5..096ad63 100644 > --- a/include/linux/kexec.h > +++ b/include/linux/kexec.h > @@ -63,6 +63,10 @@ > > #define KEXEC_CORE_NOTE_NAME CRASH_CORE_NOTE_NAME > > +#ifndef CRASH_ALIGN > +#define CRASH_ALIGN SZ_128M > +#endif Why 128M? Wouldn't we rather each architecture tells us its minimum alignment? > diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c > index d714044..3492abd 100644 > --- a/kernel/kexec_core.c > +++ b/kernel/kexec_core.c > @@ -39,6 +39,8 @@ > #include > #include > #include > +#include > +#include > > #include > #include > @@ -96,6 +98,60 @@ int kexec_crash_loaded(void) > } > EXPORT_SYMBOL_GPL(kexec_crash_loaded); > > +int __init reserve_crashkernel_low(void) > +{ > + unsigned long long base, low_base = 0, low_size = 0; > + unsigned long total_low_mem; > + int ret; > + > + total_low_mem = memblock_mem_size(1UL << (32 - PAGE_SHIFT)); > + > + /* crashkernel=Y,low */ > + ret = parse_crashkernel_low(boot_command_line, total_low_mem, > + &low_size, &base); > + if (ret) { > + /* > + * two parts from lib/swiotlb.c: > + * -swiotlb size: user-specified with swiotlb= or default. > + * > + * -swiotlb overflow buffer: now hardcoded to 32k. We round it > + * to 8M for other buffers that may need to stay low too. Also > + * make sure we allocate enough extra low memory so that we > + * don't run out of DMA buffers for 32-bit devices. > + */ > + low_size = max(swiotlb_size_or_default() + (8UL << 20), SZ_8M? > + 256UL << 20); SZ_256M? > + } else { > + /* passed with crashkernel=0,low ? */ > + if (!low_size) > + return 0; > + } > + > + low_base = memblock_find_in_range(0, 1ULL << 32, low_size, CRASH_ALIGN); > + if (!low_base) { > + pr_err("Cannot reserve %ldMB crashkernel low memory, please try smaller size.\n", > + (unsigned long)(low_size >> 20)); > + return -ENOMEM; > + } > + > + ret = memblock_reserve(low_base, low_size); > + if (ret) { > + pr_err("%s: Error reserving crashkernel low memblock.\n", > + __func__); > + return ret; > + } > + > + pr_info("Reserving %ldMB of low memory at %ldMB for crashkernel (System low RAM: %ldMB)\n", > + (unsigned long)(low_size >> 20), > + (unsigned long)(low_base >> 20), > + (unsigned long)(total_low_mem >> 20)); > + > + crashk_low_res.start = low_base; > + crashk_low_res.end = low_base + low_size - 1; > + > + return 0; > +} Thanks, James