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=-10.6 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 50707C433E9 for ; Fri, 26 Feb 2021 10:44:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 08D1164ED2 for ; Fri, 26 Feb 2021 10:44:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230083AbhBZKo1 (ORCPT ); Fri, 26 Feb 2021 05:44:27 -0500 Received: from szxga06-in.huawei.com ([45.249.212.32]:12954 "EHLO szxga06-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231219AbhBZKoC (ORCPT ); Fri, 26 Feb 2021 05:44:02 -0500 Received: from DGGEMS403-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga06-in.huawei.com (SkyGuard) with ESMTP id 4Dn5nK5TKZzjRDC; Fri, 26 Feb 2021 18:41:57 +0800 (CST) Received: from [10.174.176.191] (10.174.176.191) by DGGEMS403-HUB.china.huawei.com (10.3.19.203) with Microsoft SMTP Server id 14.3.498.0; Fri, 26 Feb 2021 18:43:08 +0800 Subject: Re: [PATCH v14 08/11] arm64: kdump: reimplement crashkernel=X To: Catalin Marinas , References: <20210130071025.65258-1-chenzhou10@huawei.com> <20210130071025.65258-9-chenzhou10@huawei.com> <20210224160408.GC28965@arm.com> <94cc9191-4eff-355f-ff02-1c5da416960e@huawei.com> CC: , , , , , , , , , , , , , , , , , , , , , From: chenzhou Message-ID: <4722d365-154b-d3bb-3897-92f229e8e84f@huawei.com> Date: Fri, 26 Feb 2021 18:43:07 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 MIME-Version: 1.0 In-Reply-To: <94cc9191-4eff-355f-ff02-1c5da416960e@huawei.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.176.191] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/2/26 18:31, chenzhou wrote: > > On 2021/2/25 0:04, Catalin Marinas wrote: >> On Sat, Jan 30, 2021 at 03:10:22PM +0800, Chen Zhou wrote: >>> There are following issues in arm64 kdump: >>> 1. We use crashkernel=X to reserve crashkernel below 4G, which >>> will fail when there is no enough low memory. >>> 2. If reserving crashkernel above 4G, in this case, crash dump >>> kernel will boot failure because there is no low memory available >>> for allocation. >>> >>> To solve these issues, change the behavior of crashkernel=X and >>> introduce crashkernel=X,[high,low]. crashkernel=X tries low allocation >>> in DMA zone, and fall back to high allocation if it fails. >>> We can also use "crashkernel=X,high" to select a region above DMA zone, >>> which also tries to allocate at least 256M in DMA zone automatically. >>> "crashkernel=Y,low" can be used to allocate specified size low memory. >>> >>> Another minor change, there may be two regions reserved for crash >>> dump kernel, in order to distinct from the high region and make no >>> effect to the use of existing kexec-tools, rename the low region as >>> "Crash kernel (low)". >> I think we discussed this but I don't remember the conclusion. Is this >> only renamed conditionally so that we don't break current kexec-tools? > Yes. >> IOW, assuming that the full crashkernel region is reserved below 4GB, >> does the "(low)" suffix still appear or it's only if a high region is >> additionally reserved? > Suffix "low" only appear if a high region is additionally reserved. >>> diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h >>> index 3f6ecae0bc68..f0caed0cb5e1 100644 >>> --- a/arch/arm64/include/asm/kexec.h >>> +++ b/arch/arm64/include/asm/kexec.h >>> @@ -96,6 +96,10 @@ static inline void crash_prepare_suspend(void) {} >>> static inline void crash_post_resume(void) {} >>> #endif >>> >>> +#ifdef CONFIG_KEXEC_CORE >>> +extern void __init reserve_crashkernel(void); >>> +#endif >> Why not have this in some generic header? >> >>> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c >>> index c18aacde8bb0..69c592c546de 100644 >>> --- a/arch/arm64/kernel/setup.c >>> +++ b/arch/arm64/kernel/setup.c >>> @@ -238,7 +238,18 @@ static void __init request_standard_resources(void) >>> kernel_data.end <= res->end) >>> request_resource(res, &kernel_data); >>> #ifdef CONFIG_KEXEC_CORE >>> - /* Userspace will find "Crash kernel" region in /proc/iomem. */ >>> + /* >>> + * Userspace will find "Crash kernel" or "Crash kernel (low)" >>> + * region in /proc/iomem. >>> + * In order to distinct from the high region and make no effect >>> + * to the use of existing kexec-tools, rename the low region as >>> + * "Crash kernel (low)". >>> + */ >>> + if (crashk_low_res.end && crashk_low_res.start >= res->start && >>> + crashk_low_res.end <= res->end) { >>> + crashk_low_res.name = "Crash kernel (low)"; >>> + request_resource(res, &crashk_low_res); >>> + } >>> if (crashk_res.end && crashk_res.start >= res->start && >>> crashk_res.end <= res->end) >>> request_resource(res, &crashk_res); >> My reading of the new generic reserve_crashkernel() is that >> crashk_low_res will only be populated if crask_res is above 4GB. If >> that's correct, I'm fine with the renaming here since current systems >> would not get a renamed low reservation (as long as they don't change >> the kernel cmdline). >> >>> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c >>> index 912f64f505f7..d20f5c444ebf 100644 >>> --- a/arch/arm64/mm/init.c >>> +++ b/arch/arm64/mm/init.c >>> @@ -35,6 +35,7 @@ >>> #include >>> #include >>> #include >>> +#include >>> #include >>> #include >>> #include >>> @@ -61,66 +62,11 @@ EXPORT_SYMBOL(memstart_addr); >>> */ >>> phys_addr_t arm64_dma_phys_limit __ro_after_init; >>> >>> -#ifdef CONFIG_KEXEC_CORE >>> -/* >>> - * reserve_crashkernel() - reserves memory for crash kernel >>> - * >>> - * This function reserves memory area given in "crashkernel=" kernel command >>> - * line parameter. The memory reserved is used by dump capture kernel when >>> - * primary kernel is crashing. >>> - */ >>> +#ifndef CONFIG_KEXEC_CORE >>> static void __init reserve_crashkernel(void) >>> { >> [...] >>> } >>> +#endif >> Can we not have the dummy reserve_crashkernel() in the generic code as >> well and avoid the #ifndef here? > You mean put the dummy reserve_crashkernel() and the relate function declaration in some generic header? > > Baoquan also mentioned about this. > Now all the arch that support kdump have the dummy reserve_crashkernel() and > function declaration, such as arm/arm64/ppc/s390.. > > But currently different arch may have different CONFIG and different function declaration about this, > for example, > > for s390, > static void __init reserve_crashkernel(void) > { > #ifdef CONFIG_CRASH_DUMP > ... > #endif > } > > for ppc, > #ifdef CONFIG_KEXEC_CORE > extern void reserve_crashkernel(void); > #else > static inline void reserve_crashkernel(void) { ; } > #endif > > If we move these to generic header we need think about: > 1. the related config in different arch > 2. function declaration(static/non static) > > As Baoquan said in patch 9, how about leave with it for now and i try to solve this later? > >>> #ifdef CONFIG_CRASH_DUMP >>> static int __init early_init_dt_scan_elfcorehdr(unsigned long node, >>> @@ -446,6 +392,14 @@ void __init bootmem_init(void) >>> * reserved, so do it here. >>> */ >>> reserve_crashkernel(); >>> +#ifdef CONFIG_KEXEC_CORE >>> + /* >>> + * The low region is intended to be used for crash dump kernel devices, >>> + * just mark the low region as "nomap" simply. >>> + */ >>> + if (crashk_low_res.end) >>> + memblock_mark_nomap(crashk_low_res.start, resource_size(&crashk_low_res)); >>> +#endif >> Do we do something similar for crashk_res? > Not. In the primary kernel(production kernel), we need to use crashk_res memory for crash kernel > elf core header, initrd... Sorry, missed one comma after crash kernel. Not. In the primary kernel(production kernel), we need to use crashk_res memory for crash kernel, elf core header, initrd and so on. > > Different with this, the crashk_low_res is only for crash dump kernel devices. >> Also, I can see we call crash_exclude_mem_range() only for crashk_res. >> Do we need to do this for crashk_low_res as well? > You are right, i missed about this. Will do in next version. > > Thanks, > Chen Zhou