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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5DFB5C433F5 for ; Fri, 11 Feb 2022 10:45:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date: Message-ID:From:References:CC:To:Subject:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=kz530DpCpMgg8FjWGlAz3Xi8dAvRs7B3UFQr2OnC2ts=; b=bqk2D6aG96gu8BqhcOdXAo1EqI 2W1M2/qk4r2VLKzvBj/Qdj3kqnKJlbSBRucCY4NoK2LnVRWZtJh0aU7FLlgpp/yrnEd/zhjupRDt4 oOrdM5iB9MAwyaNQVe3hifAf5wpmb8nqUdXFZAdGotmwiboFgXUX1wLwntVvgz0xZYN4mZy2idMF8 1rJPRtJQHxC96uCuDJaYmkutg9UybeDxRreH9chwGK4bLSaRnJmmGi/zYWugNwTOzwBMwpRlDAAEh Fe05s8tqNq39e9YsO27L+uqxcFK9Wu/cKtoPbxpbh9Jq/rTp9mrVmk9fLTBq2XN2BvLFtIpeTo0Ke FKwjLqTA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nITOy-006eGf-3W; Fri, 11 Feb 2022 10:43:44 +0000 Received: from szxga02-in.huawei.com ([45.249.212.188]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nITNS-006dPM-FP; Fri, 11 Feb 2022 10:42:13 +0000 Received: from dggpemm500023.china.huawei.com (unknown [172.30.72.54]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4Jw9Bj5QMdzbkGg; Fri, 11 Feb 2022 18:41:01 +0800 (CST) Received: from dggpemm500006.china.huawei.com (7.185.36.236) by dggpemm500023.china.huawei.com (7.185.36.83) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Fri, 11 Feb 2022 18:42:04 +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; Fri, 11 Feb 2022 18:42:03 +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> From: "Leizhen (ThunderTown)" Message-ID: <6ac0c60c-78bc-9789-9f5c-659fb5fa3e9a@huawei.com> Date: Fri, 11 Feb 2022 18:41:51 +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-Language: en-US X-Originating-IP: [10.174.178.55] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpemm500006.china.huawei.com (7.185.36.236) X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220211_024210_922304_07E63590 X-CRM114-Status: GOOD ( 20.77 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 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. <--------- > >> + >> + 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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel