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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 835DFC433F5 for ; Mon, 14 Feb 2022 06:44:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231370AbiBNGoZ (ORCPT ); Mon, 14 Feb 2022 01:44:25 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:45830 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235037AbiBNGoY (ORCPT ); Mon, 14 Feb 2022 01:44:24 -0500 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 89C154D62F; Sun, 13 Feb 2022 22:44:16 -0800 (PST) Received: from dggpemm500021.china.huawei.com (unknown [172.30.72.53]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4JxvmG165qz9sdJ; Mon, 14 Feb 2022 14:42:38 +0800 (CST) Received: from dggpemm500006.china.huawei.com (7.185.36.236) by dggpemm500021.china.huawei.com (7.185.36.109) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Mon, 14 Feb 2022 14:44:13 +0800 Received: from [10.174.178.55] (10.174.178.55) by dggpemm500006.china.huawei.com (7.185.36.236) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Mon, 14 Feb 2022 14:44:12 +0800 Subject: Re: [PATCH v20 3/5] arm64: kdump: reimplement crashkernel=X To: Baoquan He CC: Thomas Gleixner , Ingo Molnar , Borislav Petkov , , "H . Peter Anvin" , , Dave Young , Vivek Goyal , Eric Biederman , , Catalin Marinas , Will Deacon , , Rob Herring , Frank Rowand , , "Jonathan Corbet" , , Randy Dunlap , Feng Zhou , Kefeng Wang , Chen Zhou , "John Donnelly" , Dave Kleikamp References: <20220124084708.683-1-thunder.leizhen@huawei.com> <20220124084708.683-4-thunder.leizhen@huawei.com> <6ac0c60c-78bc-9789-9f5c-659fb5fa3e9a@huawei.com> From: "Leizhen (ThunderTown)" Message-ID: <441c2917-bd86-da71-22d2-f526baf1457f@huawei.com> Date: Mon, 14 Feb 2022 14:44:01 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.178.55] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To dggpemm500006.china.huawei.com (7.185.36.236) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On 2022/2/11 18:51, Baoquan He wrote: > On 02/11/22 at 06:41pm, Leizhen (ThunderTown) wrote: >> >> >> On 2022/2/11 18:30, Baoquan He wrote: >>> On 01/24/22 at 04:47pm, Zhen Lei wrote: >>>> From: Chen Zhou >>> ...... >>>> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c >>>> index 6c653a2c7cff052..a5d43feac0d7d96 100644 >>>> --- a/arch/arm64/mm/init.c >>>> +++ b/arch/arm64/mm/init.c >>>> @@ -71,6 +71,30 @@ phys_addr_t arm64_dma_phys_limit __ro_after_init; >>>> #define CRASH_ADDR_LOW_MAX arm64_dma_phys_limit >>>> #define CRASH_ADDR_HIGH_MAX MEMBLOCK_ALLOC_ACCESSIBLE >>>> >>>> +static int __init reserve_crashkernel_low(unsigned long long low_size) >>>> +{ >>>> + unsigned long long low_base; >>>> + >>>> + /* passed with crashkernel=0,low ? */ >>>> + if (!low_size) >>>> + return 0; >>>> + >>>> + low_base = memblock_phys_alloc_range(low_size, CRASH_ALIGN, 0, CRASH_ADDR_LOW_MAX); >>>> + if (!low_base) { >>>> + pr_err("cannot allocate crashkernel low memory (size:0x%llx).\n", low_size); >>>> + return -ENOMEM; >>>> + } >>>> + >>>> + pr_info("crashkernel low memory reserved: 0x%llx - 0x%llx (%lld MB)\n", >>>> + low_base, low_base + low_size, low_size >> 20); >>>> + >>>> + crashk_low_res.start = low_base; >>>> + crashk_low_res.end = low_base + low_size - 1; >>>> + insert_resource(&iomem_resource, &crashk_low_res); >>>> + >>>> + return 0; >>>> +} >>>> + >>>> /* >>>> * reserve_crashkernel() - reserves memory for crash kernel >>>> * >>>> @@ -81,29 +105,62 @@ phys_addr_t arm64_dma_phys_limit __ro_after_init; >>>> static void __init reserve_crashkernel(void) >>>> { >>>> unsigned long long crash_base, crash_size; >>>> + unsigned long long crash_low_size = SZ_256M; >>>> unsigned long long crash_max = CRASH_ADDR_LOW_MAX; >>>> int ret; >>>> + bool fixed_base; >>>> + char *cmdline = boot_command_line; >>>> >>>> - ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(), >>>> + /* crashkernel=X[@offset] */ >>>> + ret = parse_crashkernel(cmdline, memblock_phys_mem_size(), >>>> &crash_size, &crash_base); >>>> - /* no crashkernel= or invalid value specified */ >>>> - if (ret || !crash_size) >>>> - return; >>>> + if (ret || !crash_size) { >>>> + unsigned long long low_size; >>>> >>>> + /* crashkernel=X,high */ >>>> + ret = parse_crashkernel_high(cmdline, 0, &crash_size, &crash_base); >>>> + if (ret || !crash_size) >>>> + return; >>>> + >>>> + /* crashkernel=X,low */ >>>> + ret = parse_crashkernel_low(cmdline, 0, &low_size, &crash_base); >>>> + if (!ret) >>>> + crash_low_size = low_size; >>> >>> Here, the error case is not checked and handled. But it still gets >>> expeced result which is the default SZ_256M. Is this designed on >>> purpose? >> >> Yes, we can specify only "crashkernel=X,high". >> >> This is mentioned in Documentation/admin-guide/kernel-parameters.txt >> >> crashkernel=size[KMG],low >> [KNL, X86-64] range under 4G. When crashkernel=X,high >> is passed, kernel could allocate physical memory region >> above 4G, that cause second kernel crash on system >> that require some amount of low memory, e.g. swiotlb >> requires at least 64M+32K low memory, also enough extra >> low memory is needed to make sure DMA buffers for 32-bit >> devices won't run out. Kernel would try to allocate at <--------- >> least 256M below 4G automatically. <--------- > > Yeah, that is expected becasue no crahskernel=,low is a right usage. The > 'ret' is 0 in the case. If I gave below string, it works too. > "crashkernel=256M,high crashkernel=aaabbadfadfd,low" Yes, so maybe we should change the error code in __parse_crashkernel() from "-EINVAL" to "-ENOENT" when the specified option does not exist. diff --git a/kernel/crash_core.c b/kernel/crash_core.c index 256cf6db573cd09..395f4fac1773f28 100644 --- a/kernel/crash_core.c +++ b/kernel/crash_core.c @@ -243,9 +243,8 @@ static int __init __parse_crashkernel(char *cmdline, *crash_base = 0; ck_cmdline = get_last_crashkernel(cmdline, name, suffix); - if (!ck_cmdline) - return -EINVAL; + return -ENOENT; ck_cmdline += strlen(name); > >> >>> >>>> + >>>> + crash_max = CRASH_ADDR_HIGH_MAX; >>>> + } >>>> + >>>> + fixed_base = !!crash_base; >>>> crash_size = PAGE_ALIGN(crash_size); >>>> >>>> /* User specifies base address explicitly. */ >>>> if (crash_base) >>>> crash_max = crash_base + crash_size; >>>> >>>> +retry: >>>> crash_base = memblock_phys_alloc_range(crash_size, CRASH_ALIGN, >>>> crash_base, crash_max); >>>> if (!crash_base) { >>>> + /* >>>> + * Attempt to fully allocate low memory failed, fall back >>>> + * to high memory, the minimum required low memory will be >>>> + * reserved later. >>>> + */ >>>> + if (!fixed_base && (crash_max == CRASH_ADDR_LOW_MAX)) { >>>> + crash_max = CRASH_ADDR_HIGH_MAX; >>>> + goto retry; >>>> + } >>>> + >>>> pr_warn("cannot allocate crashkernel (size:0x%llx)\n", >>>> crash_size); >>>> return; >>>> } >>>> >>>> + if (crash_base >= SZ_4G && reserve_crashkernel_low(crash_low_size)) { >>>> + memblock_phys_free(crash_base, crash_size); >>>> + return; >>>> + } >>>> + >>>> pr_info("crashkernel reserved: 0x%016llx - 0x%016llx (%lld MB)\n", >>>> crash_base, crash_base + crash_size, crash_size >> 20); >>>> >>>> @@ -112,6 +169,9 @@ static void __init reserve_crashkernel(void) >>>> * map. Inform kmemleak so that it won't try to access it. >>>> */ >>>> kmemleak_ignore_phys(crash_base); >>>> + if (crashk_low_res.end) >>>> + kmemleak_ignore_phys(crashk_low_res.start); >>>> + >>>> crashk_res.start = crash_base; >>>> crashk_res.end = crash_base + crash_size - 1; >>>> insert_resource(&iomem_resource, &crashk_res); >>>> -- >>>> 2.25.1 >>>> >>> >>> . >>> >> >> -- >> Regards, >> Zhen Lei >> > > . > -- Regards, Zhen Lei