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 99228C433F5 for ; Wed, 16 Mar 2022 13:19:13 +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=VtguWu4mfyMmdOqLdcjI8r6tD7MLJzjG9CwbpIOhsOQ=; b=1FQ+RbjlUKix5pfT68U01MYmcC TQTqrdrLNQn4gAjUR3uYrlJ2f66w7Ze7WbLqsZHnaAc7lx9vXGK2qqt6T4OUmTzGMaN71BW6qAxwY 07RXT6GWchdnCyyhIUOIW0Xejx4TzU6tMPp8MoaAx8tdKFYJXvbmqcKkFULkYISYeiOYZpeymyZL/ MHhwpDRmCBcZVHz4FRRsk5mm87P+Ca629DdxvKfFAbhbTXhJBmTaKHv47r4PSqTeZrjrH7nB4qQu0 L8TP43yt1nbXX9bJO//e7OIM1K3dFgJdMiWFqy38TnAOYXT09jP2mB/D0hYilQaJvQorb3BNs4dpo PdQXgv+w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nUTWo-00CxDG-48; Wed, 16 Mar 2022 13:17:26 +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 1nUTRB-00Cuio-NQ; Wed, 16 Mar 2022 13:11:48 +0000 Received: from dggpemm500020.china.huawei.com (unknown [172.30.72.57]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4KJVwp6H64zCqk1; Wed, 16 Mar 2022 21:09:30 +0800 (CST) Received: from dggpemm500006.china.huawei.com (7.185.36.236) by dggpemm500020.china.huawei.com (7.185.36.49) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Wed, 16 Mar 2022 21:11:32 +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; Wed, 16 Mar 2022 21:11:31 +0800 Subject: Re: [PATCH v21 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: <20220227030717.1464-1-thunder.leizhen@huawei.com> <20220227030717.1464-4-thunder.leizhen@huawei.com> From: "Leizhen (ThunderTown)" Message-ID: <7d7a3e70-6a46-b722-ef48-7206a47185dd@huawei.com> Date: Wed, 16 Mar 2022 21:11:30 +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-20220316_061138_269076_A4F6709B X-CRM114-Status: GOOD ( 40.67 ) 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 2022/3/16 20:11, Baoquan He wrote: > On 02/27/22 at 11:07am, Zhen Lei wrote: >> From: Chen Zhou >> >> 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. >> >> Signed-off-by: Chen Zhou >> Co-developed-by: Zhen Lei >> Signed-off-by: Zhen Lei >> --- >> arch/arm64/kernel/machine_kexec.c | 9 ++- >> arch/arm64/kernel/machine_kexec_file.c | 12 ++- >> arch/arm64/mm/init.c | 106 +++++++++++++++++++++++-- >> 3 files changed, 115 insertions(+), 12 deletions(-) >> >> diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c >> index e16b248699d5c3c..19c2d487cb08feb 100644 >> --- a/arch/arm64/kernel/machine_kexec.c >> +++ b/arch/arm64/kernel/machine_kexec.c >> @@ -329,8 +329,13 @@ bool crash_is_nosave(unsigned long pfn) >> >> /* in reserved memory? */ >> addr = __pfn_to_phys(pfn); >> - if ((addr < crashk_res.start) || (crashk_res.end < addr)) >> - return false; >> + if ((addr < crashk_res.start) || (crashk_res.end < addr)) { >> + if (!crashk_low_res.end) >> + return false; >> + >> + if ((addr < crashk_low_res.start) || (crashk_low_res.end < addr)) >> + return false; >> + } >> >> if (!kexec_crash_image) >> return true; >> diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c >> index 59c648d51848886..889951291cc0f9c 100644 >> --- a/arch/arm64/kernel/machine_kexec_file.c >> +++ b/arch/arm64/kernel/machine_kexec_file.c >> @@ -65,10 +65,18 @@ static int prepare_elf_headers(void **addr, unsigned long *sz) >> >> /* Exclude crashkernel region */ >> ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end); >> + if (ret) >> + goto out; >> + >> + if (crashk_low_res.end) { >> + ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end); >> + if (ret) >> + goto out; >> + } >> >> - if (!ret) >> - ret = crash_prepare_elf64_headers(cmem, true, addr, sz); >> + ret = crash_prepare_elf64_headers(cmem, true, addr, sz); >> >> +out: >> kfree(cmem); >> return ret; >> } >> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c >> index 90f276d46b93bc6..30ae6638ff54c47 100644 >> --- a/arch/arm64/mm/init.c >> +++ b/arch/arm64/mm/init.c >> @@ -65,6 +65,44 @@ EXPORT_SYMBOL(memstart_addr); >> phys_addr_t arm64_dma_phys_limit __ro_after_init; >> >> #ifdef CONFIG_KEXEC_CORE >> +/* Current arm64 boot protocol requires 2MB alignment */ >> +#define CRASH_ALIGN SZ_2M >> + >> +#define CRASH_ADDR_LOW_MAX arm64_dma_phys_limit >> +#define CRASH_ADDR_HIGH_MAX memblock.current_limit >> + >> +/* >> + * This is an empirical value in x86_64 and taken here directly. Please >> + * refer to the code comment in reserve_crashkernel_low() of x86_64 for more >> + * details. >> + */ >> +#define DEFAULT_CRASH_KERNEL_LOW_SIZE \ >> + max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20) >> + >> +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%08llx - 0x%08llx (%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 >> * >> @@ -75,30 +113,79 @@ 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_max = arm64_dma_phys_limit; >> + unsigned long long crash_low_size; >> + unsigned long long crash_max = CRASH_ADDR_LOW_MAX; >> int ret; > > Even though reverse xmas tree style is not enforced, this 'int ret;' is > really annoying to look at. Maybe move it down two lines. > >> + bool fixed_base, high = false; >> + 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) { >> + /* crashkernel=X,high */ >> + ret = parse_crashkernel_high(cmdline, 0, &crash_size, &crash_base); >> + if (ret || !crash_size) >> + return; >> + >> + /* crashkernel=Y,low */ >> + ret = parse_crashkernel_low(cmdline, 0, &crash_low_size, &crash_base); >> + if (ret == -ENOENT) >> + /* >> + * crashkernel=Y,low is not specified explicitly, use >> + * default size automatically. >> + */ >> + crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE; >> + else if (ret) >> + /* crashkernel=Y,low is specified but Y is invalid */ >> + return; >> + >> + /* Mark crashkernel=X,high is specified */ >> + high = true; >> + crash_max = CRASH_ADDR_HIGH_MAX; >> + } >> >> + fixed_base = !!crash_base; >> crash_size = PAGE_ALIGN(crash_size); >> >> /* User specifies base address explicitly. */ > This is over commenting, can't see why it's needed. >> - if (crash_base) >> + if (fixed_base) >> crash_max = crash_base + crash_size; > > Hi leizhen, > > I made change on reserve_crashkenrel(), inline comment may be slow. > Please check and consider if they can be taken. That's great. Thank you very much. > > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > index 30ae6638ff54..f96351da1e3e 100644 > --- a/arch/arm64/mm/init.c > +++ b/arch/arm64/mm/init.c > @@ -109,38 +109,43 @@ static int __init reserve_crashkernel_low(unsigned long long low_size) > * 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. > + * > + * NOTE: Reservation of crashkernel,low is special since its existence > + * is not independent, need rely on the existence of crashkernel,high. > + * Hence there are different cases for crashkernel,low reservation: > + * 1) crashkernel=Y,low is specified explicitly, crashkernel,low takes Y; > + * 2) crashkernel=,low is not given, while crashkernel=,high is specified, > + * take the default crashkernel,low value; > + * 3) crashkernel=X is specified, while fallback to get a memory region > + * in high memory, take the default crashkernel,low value; > + * 4) crashkernel='invalid value',low is specified, failed the whole > + * crashkernel reservation and bail out. > */ > static void __init reserve_crashkernel(void) > { > unsigned long long crash_base, crash_size; > unsigned long long crash_low_size; > unsigned long long crash_max = CRASH_ADDR_LOW_MAX; > - int ret; > bool fixed_base, high = false; > char *cmdline = boot_command_line; > + int ret; > > /* crashkernel=X[@offset] */ > ret = parse_crashkernel(cmdline, memblock_phys_mem_size(), > &crash_size, &crash_base); > if (ret || !crash_size) { > - /* crashkernel=X,high */ > ret = parse_crashkernel_high(cmdline, 0, &crash_size, &crash_base); > if (ret || !crash_size) > return; > > - /* crashkernel=Y,low */ > ret = parse_crashkernel_low(cmdline, 0, &crash_low_size, &crash_base); > if (ret == -ENOENT) > - /* > - * crashkernel=Y,low is not specified explicitly, use > - * default size automatically. > - */ > + /* case #2 of crashkernel,low reservation */ > crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE; > else if (ret) > - /* crashkernel=Y,low is specified but Y is invalid */ > + /* case #4 of crashkernel,low reservation */ > return; > > - /* Mark crashkernel=X,high is specified */ > high = true; > crash_max = CRASH_ADDR_HIGH_MAX; > } > @@ -148,7 +153,6 @@ static void __init reserve_crashkernel(void) > fixed_base = !!crash_base; > crash_size = PAGE_ALIGN(crash_size); > > - /* User specifies base address explicitly. */ > if (fixed_base) > crash_max = crash_base + crash_size; > > @@ -172,11 +176,7 @@ static void __init reserve_crashkernel(void) > } > > if (crash_base >= SZ_4G) { > - /* > - * For case crashkernel=X, low memory is not enough and fall > - * back to reserve specified size of memory above 4G, try to > - * allocate minimum required memory below 4G again. > - */ > + /* case #3 of crashkernel,low reservation */ > if (!high) > crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE; > > >> >> - /* Current arm64 boot protocol requires 2MB alignment */ >> - crash_base = memblock_phys_alloc_range(crash_size, SZ_2M, >> +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) { >> + /* >> + * For case crashkernel=X, low memory is not enough and fall >> + * back to reserve specified size of memory above 4G, try to >> + * allocate minimum required memory below 4G again. >> + */ >> + if (!high) >> + crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE; >> + >> + if (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); >> >> @@ -107,6 +194,9 @@ 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