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 <chenzhou10@xxxxxxxxxx> >>> ...... >>>> 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 _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec