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,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,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 A3C42C433DB for ; Fri, 26 Feb 2021 10:32:39 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 3ACAB64EED for ; Fri, 26 Feb 2021 10:32:39 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3ACAB64EED Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=RNLOJSn3HlkBK/leLxxJQoMMdEWtqdzHBQdVf+IepLc=; b=Zu8aXocCeCpQiBj3anA0pwHQk NzZ9OyCl+93M+JEEm6wmg2M86txlAl3r2jnZyk2MUaoiaqkArIZRKHvYGZTY3Wx4ap1WFk1bGPfoB 0d8YYj0zPcHpum2BNKE9Zh3r0AyfKhz8uBoys9tD4/ZnAsZcTX0uMtZRqgF8EVK+YJ9DYe140nYwL HzATFQ8Pa9XOp9oR/+z3cKz1KQFRpkOMBBXCpuihhQ7QxE2ukaTAmC9YtWyGyeuak/b/s57Uk40bx F/NTIlm6TOAO3ijBy0QdauDfQoO0+CS5MzdnkbFB6XGYWuLzxCQCPjpGvDIJmA4a4HthhztIlIqds f1KM9E2zA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1lFaPB-0002Nv-Er; Fri, 26 Feb 2021 10:31:29 +0000 Received: from szxga05-in.huawei.com ([45.249.212.191]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1lFaP5-0002Jj-EA; Fri, 26 Feb 2021 10:31:24 +0000 Received: from DGGEMS402-HUB.china.huawei.com (unknown [172.30.72.58]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4Dn5Vb42nhzMfKd; Fri, 26 Feb 2021 18:29:11 +0800 (CST) Received: from [10.174.176.191] (10.174.176.191) by DGGEMS402-HUB.china.huawei.com (10.3.19.202) with Microsoft SMTP Server id 14.3.498.0; Fri, 26 Feb 2021 18:31:07 +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> From: chenzhou Message-ID: <94cc9191-4eff-355f-ff02-1c5da416960e@huawei.com> Date: Fri, 26 Feb 2021 18:31:06 +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: <20210224160408.GC28965@arm.com> X-Originating-IP: [10.174.176.191] X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210226_053123_980024_609F2394 X-CRM114-Status: GOOD ( 28.91 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: wangkefeng.wang@huawei.com, linux-doc@vger.kernel.org, bhsharma@redhat.com, huawei.libin@huawei.com, guohanjun@huawei.com, will@kernel.org, corbet@lwn.net, mingo@redhat.com, dyoung@redhat.com, John.P.donnelly@oracle.com, arnd@arndb.de, xiexiuqi@huawei.com, horms@verge.net.au, tglx@linutronix.de, linux-arm-kernel@lists.infradead.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, robh+dt@kernel.org, james.morse@arm.com, nsaenzjulienne@suse.de, prabhakar.pkin@gmail.com, rppt@kernel.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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... 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 > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel