Re: [PATCH v7 2/4] arm64: kdump: reserve crashkenel above 4G for crash dump kernel

From: chenzhou
Date: Mon Mar 09 2020 - 21:30:55 EST


Hi,

On 2020/3/9 23:51, Prabhakar Kushwaha wrote:
> On 3/9/2020 10:18 AM, Prabhakar Kushwaha wrote:
>> Hi Chen,
>>
>> On Sat, Mar 7, 2020 at 4:36 PM Chen Zhou <chenzhou10@xxxxxxxxxx> wrote:
>>>
>>>
>>>
>>> On 2020/3/5 18:13, Prabhakar Kushwaha wrote:
>>>> On Mon, Dec 23, 2019 at 8:57 PM Chen Zhou <chenzhou10@xxxxxxxxxx> wrote:
>>>>>
>>>>> Crashkernel=X tries to reserve memory for the crash dump kernel under
>>>>> 4G. If crashkernel=X,low is specified simultaneously, reserve spcified
>>>>> size low memory for crash kdump kernel devices firstly and then reserve
>>>>> memory above 4G.
>>>>>
>>>>> Signed-off-by: Chen Zhou <chenzhou10@xxxxxxxxxx>
>>>>> ---
>>>>> arch/arm64/kernel/setup.c | 8 +++++++-
>>>>> arch/arm64/mm/init.c | 31 +++++++++++++++++++++++++++++--
>>>>> 2 files changed, 36 insertions(+), 3 deletions(-)
>>>>>
>>>>> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
>>>>> index 56f6645..04d1c87 100644
>>>>> --- a/arch/arm64/kernel/setup.c
>>>>> +++ b/arch/arm64/kernel/setup.c
>>>>> @@ -238,7 +238,13 @@ 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" region in /proc/iomem.
>>>>> + * Note: the low region is renamed as Crash kernel (low).
>>>>> + */
>>>>> + if (crashk_low_res.end && crashk_low_res.start >= res->start &&
>>>>> + crashk_low_res.end <= res->end)
>>>>> + 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);
>>>>> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
>>>>> index b65dffd..0d7afd5 100644
>>>>> --- a/arch/arm64/mm/init.c
>>>>> +++ b/arch/arm64/mm/init.c
>>>>> @@ -80,6 +80,7 @@ static void __init reserve_crashkernel(void)
>>>>> {
>>>>> unsigned long long crash_base, crash_size;
>>>>> int ret;
>>>>> + phys_addr_t crash_max = arm64_dma32_phys_limit;
>>>>>
>>>>> ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
>>>>> &crash_size, &crash_base);
>>>>> @@ -87,12 +88,38 @@ static void __init reserve_crashkernel(void)
>>>>> if (ret || !crash_size)
>>>>> return;
>>>>>
>>>>> + ret = reserve_crashkernel_low();
>>>>> + if (!ret && crashk_low_res.end) {
>>>>> + /*
>>>>> + * If crashkernel=X,low specified, there may be two regions,
>>>>> + * we need to make some changes as follows:
>>>>> + *
>>>>> + * 1. rename the low region as "Crash kernel (low)"
>>>>> + * 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)".
>>>>> + *
>>>>> + * 2. change the upper bound for crash memory
>>>>> + * Set MEMBLOCK_ALLOC_ACCESSIBLE upper bound for crash memory.
>>>>> + *
>>>>> + * 3. mark the low region as "nomap"
>>>>> + * The low region is intended to be used for crash dump kernel
>>>>> + * devices, just mark the low region as "nomap" simply.
>>>>> + */
>>>>> + const char *rename = "Crash kernel (low)";
>>>>> +
>>>>> + crashk_low_res.name = rename;
>>>>> + crash_max = MEMBLOCK_ALLOC_ACCESSIBLE;
>>>>> + memblock_mark_nomap(crashk_low_res.start,
>>>>> + resource_size(&crashk_low_res));
>>>>> + }
>>>>> +
>>>>> crash_size = PAGE_ALIGN(crash_size);
>>>>>
>>>>> if (crash_base == 0) {
>>>>> /* Current arm64 boot protocol requires 2MB alignment */
>>>>> - crash_base = memblock_find_in_range(0, arm64_dma32_phys_limit,
>>>>> - crash_size, SZ_2M);
>>>>> + crash_base = memblock_find_in_range(0, crash_max, crash_size,
>>>>> + SZ_2M);
>>>>> if (crash_base == 0) {
>>>>> pr_warn("cannot allocate crashkernel (size:0x%llx)\n",
>>>>> crash_size);
>>>>> --
>>>>
>>>> I tested this patch series on ARM64-ThunderX2 with no issue with
>>>> bootargs crashkenel=X@Y crashkernel=250M,low
>>>>
>>>> $ dmesg | grep crash
>>>> [ 0.000000] crashkernel reserved: 0x0000000b81200000 -
>>>> 0x0000000c81200000 (4096 MB)
>>>> [ 0.000000] Kernel command line:
>>>> BOOT_IMAGE=/boot/vmlinuz-5.6.0-rc4+
>>>> root=UUID=866b8df3-14f4-4e11-95a1-74a90ee9b694 ro
>>>> crashkernel=4G@0xb81200000 crashkernel=250M,low nowatchdog earlycon
>>>> [ 29.310209] crashkernel=250M,low
>>>>
>>>> $ kexec -p -i /boot/vmlinuz-`uname -r`
>>>> --initrd=/boot/initrd.img-`uname -r` --reuse-cmdline
>>>> $ echo 1 > /proc/sys/kernel/sysrq ; echo c > /proc/sysrq-trigger
>>>>
>>>> But when i tried with crashkernel=4G crashkernel=250M,low as bootargs.
>>>> Kernel is not able to allocate memory.
>>>> [ 0.000000] cannot allocate crashkernel (size:0x100000000)
>>>> [ 0.000000] Kernel command line:
>>>> BOOT_IMAGE=/boot/vmlinuz-5.6.0-rc4+
>>>> root=UUID=866b8df3-14f4-4e11-95a1-74a90ee9b694 ro crashkernel=4G
>>>> crashkernel=250M,low nowatchdog
>>>> [ 29.332081] crashkernel=250M,low
>>>>
>>>> does crashkernel=X@Y mandatory to get allocated beyond 4G?
>>>> am I missing something?
>>>
>>> I can't reproduce the problem in my environment, can you test with other size,
>>> such as "crashkernel=1G crashkernel=250M,low", see if there is the same issue.
>>>
>> I tried 1G also. Same error, please find the logs
>>
>> $ dmesg | grep crash
>> [ 0.000000] cannot allocate crashkernel (size:0x40000000)
>> [ 0.000000] Kernel command line:
>> BOOT_IMAGE=/boot/vmlinuz-5.6.0-rc4+
>> root=UUID=866b8df3-14f4-4e11-95a1-74a90ee9b694 ro nowatchdog earlycon
>> crashkernel=1G crashkernel=250M,low
>> [ 29.326916] crashkernel=250M,low
>>
>>
>>> Besides, crashkernel=X@Y isn't mandatory to get allocated beyond 4G,
>>
>> this was my understanding also.
>>
>>> can you show the whole file /proc/iomem.
>>>
>>
>> $ cat /proc/iomem
>> 00000000-00000000 : PCI ECAM
>> 00000000-00000000 : PCI ECAM
>> 00000000-00000000 : PCI Bus 0000:00
>> 00000000-00000000 : PCI Bus 0000:0f
>> 00000000-00000000 : PCI Bus 0000:10
>> 00000000-00000000 : 0000:10:00.0
>> 00000000-00000000 : 0000:10:00.0
>> 00000000-00000000 : PCI Bus 0000:01
>> 00000000-00000000 : 0000:01:00.0
>> 00000000-00000000 : 0000:01:00.1
>> 00000000-00000000 : PCI Bus 0000:05
>> 00000000-00000000 : 0000:05:00.0
>> 00000000-00000000 : 0000:05:00.1
>> 00000000-00000000 : PCI Bus 0000:09
>> 00000000-00000000 : 0000:09:00.0
>> 00000000-00000000 : 0000:09:00.1
>> 00000000-00000000 : 0000:00:10.0
>> 00000000-00000000 : ahci
>> 00000000-00000000 : 0000:00:10.1
>> 00000000-00000000 : ahci
>> 00000000-00000000 : PCI Bus 0000:80
>> 00000000-00000000 : PCI Bus 0000:83
>> 00000000-00000000 : 0000:83:00.0
>> 00000000-00000000 : 0000:83:00.0
>> 00000000-00000000 : nvme
>> 00000000-00000000 : PCI Bus 0000:89
>> 00000000-00000000 : 0000:89:00.0
>> 00000000-00000000 : e1000e
>> 00000000-00000000 : 0000:89:00.0
>> 00000000-00000000 : 0000:89:00.0
>> 00000000-00000000 : e1000e
>> 00000000-00000000 : 0000:89:00.0
>> 00000000-00000000 : e1000e
>> 00000000-00000000 : PCI Bus 0000:8d
>> 00000000-00000000 : 0000:8d:00.0
>> 00000000-00000000 : 0000:8d:00.0
>> 00000000-00000000 : mpt3sas
>> 00000000-00000000 : reserved
>> 00000000-00000000 : System RAM
>> 00000000-00000000 : Kernel code
>> 00000000-00000000 : reserved
>> 00000000-00000000 : Kernel data
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : System RAM
>> 00000000-00000000 : reserved
>> 00000000-00000000 : System RAM
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : System RAM
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : System RAM
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : System RAM
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : System RAM
>> 00000000-00000000 : reserved
>> 00000000-00000000 : CAV901C:00
>> 00000000-00000000 : CAV901D:00
>> 00000000-00000000 : CAV901C:00
>> 00000000-00000000 : CAV901E:00
>> 00000000-00000000 : CAV901C:00
>> 00000000-00000000 : CAV901F:00
>> 00000000-00000000 : CAV901C:00
>> 00000000-00000000 : CAV9006:00
>> 00000000-00000000 : CAV9006:00
>> 00000000-00000000 : ARMH0011:00
>> 00000000-00000000 : ARMH0011:00
>> 00000000-00000000 : arm-smmu-v3.0.auto
>> 00000000-00000000 : arm-smmu-v3.0.auto
>> 00000000-00000000 : arm-smmu-v3.1.auto
>> 00000000-00000000 : arm-smmu-v3.1.auto
>> 00000000-00000000 : arm-smmu-v3.2.auto
>> 00000000-00000000 : arm-smmu-v3.2.auto
>> 00000000-00000000 : CAV901C:01
>> 00000000-00000000 : CAV901D:01
>> 00000000-00000000 : CAV901C:01
>> 00000000-00000000 : CAV901E:01
>> 00000000-00000000 : CAV901C:01
>> 00000000-00000000 : CAV901F:01
>> 00000000-00000000 : CAV901C:01
>> 00000000-00000000 : CAV9007:06
>> 00000000-00000000 : CAV9007:06
>> 00000000-00000000 : arm-smmu-v3.3.auto
>> 00000000-00000000 : arm-smmu-v3.3.auto
>> 00000000-00000000 : arm-smmu-v3.4.auto
>> 00000000-00000000 : arm-smmu-v3.4.auto
>> 00000000-00000000 : arm-smmu-v3.5.auto
>> 00000000-00000000 : arm-smmu-v3.5.auto
>> 00000000-00000000 : System RAM
>> 00000000-00000000 : System RAM
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : System RAM
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : reserved
>> 00000000-00000000 : PCI Bus 0000:00
>> 00000000-00000000 : PCI Bus 0000:01
>> 00000000-00000000 : 0000:01:00.0
>> 00000000-00000000 : 0000:01:00.1
>> 00000000-00000000 : 0000:01:00.0
>> 00000000-00000000 : 0000:01:00.1
>> 00000000-00000000 : 0000:01:00.0
>> 00000000-00000000 : 0000:01:00.1
>> 00000000-00000000 : PCI Bus 0000:05
>> 00000000-00000000 : 0000:05:00.0
>> 00000000-00000000 : bnx2x
>> 00000000-00000000 : 0000:05:00.1
>> 00000000-00000000 : bnx2x
>> 00000000-00000000 : 0000:05:00.0
>> 00000000-00000000 : bnx2x
>> 00000000-00000000 : 0000:05:00.0
>> 00000000-00000000 : bnx2x
>> 00000000-00000000 : 0000:05:00.1
>> 00000000-00000000 : bnx2x
>> 00000000-00000000 : 0000:05:00.1
>> 00000000-00000000 : bnx2x
>> 00000000-00000000 : PCI Bus 0000:09
>> 00000000-00000000 : 0000:09:00.0
>> 00000000-00000000 : i40e
>> 00000000-00000000 : 0000:09:00.1
>> 00000000-00000000 : i40e
>> 00000000-00000000 : 0000:09:00.0
>> 00000000-00000000 : 0000:09:00.1
>> 00000000-00000000 : 0000:09:00.0
>> 00000000-00000000 : i40e
>> 00000000-00000000 : 0000:09:00.1
>> 00000000-00000000 : i40e
>> 00000000-00000000 : 0000:09:00.0
>> 00000000-00000000 : 0000:09:00.1
>> 00000000-00000000 : 0000:00:0f.0
>> 00000000-00000000 : xhci-hcd
>> 00000000-00000000 : 0000:00:0f.0
>> 00000000-00000000 : 0000:00:0f.1
>> 00000000-00000000 : xhci-hcd
>> 00000000-00000000 : 0000:00:0f.1
>> 00000000-00000000 : 0000:00:10.0
>> 00000000-00000000 : ahci
>> 00000000-00000000 : 0000:00:10.1
>> 00000000-00000000 : ahci
>> 00000000-00000000 : PCI Bus 0000:80
>>
>
> resending with correct logs (after login as root)
>
> $ cat /proc/iomem
> 30000000-37ffffff : PCI ECAM
> 38000000-3fffffff : PCI ECAM
> 40000000-5fffffff : PCI Bus 0000:00
> 40000000-417fffff : PCI Bus 0000:0f
> 40000000-417fffff : PCI Bus 0000:10
> 40000000-40ffffff : 0000:10:00.0
> 41000000-4101ffff : 0000:10:00.0
> 41800000-418fffff : PCI Bus 0000:01
> 41800000-4183ffff : 0000:01:00.0
> 41840000-4187ffff : 0000:01:00.1
> 41900000-419fffff : PCI Bus 0000:05
> 41900000-4197ffff : 0000:05:00.0
> 41980000-419fffff : 0000:05:00.1
> 41a00000-41afffff : PCI Bus 0000:09
> 41a00000-41a7ffff : 0000:09:00.0
> 41a80000-41afffff : 0000:09:00.1
> 41b00000-41b0ffff : 0000:00:10.0
> 41b00000-41b0ffff : ahci
> 41b10000-41b1ffff : 0000:00:10.1
> 41b10000-41b1ffff : ahci
> 60000000-7fffffff : PCI Bus 0000:80
> 60000000-600fffff : PCI Bus 0000:83
> 60000000-6001ffff : 0000:83:00.0
> 60020000-60023fff : 0000:83:00.0
> 60020000-60023fff : nvme
> 60100000-601fffff : PCI Bus 0000:89
> 60100000-6017ffff : 0000:89:00.0
> 60100000-6017ffff : e1000e
> 60180000-601bffff : 0000:89:00.0
> 601c0000-601dffff : 0000:89:00.0
> 601c0000-601dffff : e1000e
> 601e0000-601e3fff : 0000:89:00.0
> 601e0000-601e3fff : e1000e
> 60200000-603fffff : PCI Bus 0000:8d
> 60200000-602fffff : 0000:8d:00.0
> 60300000-6030ffff : 0000:8d:00.0
> 60300000-6030ffff : mpt3sas
> 802f0000-8030ffff : reserved
> e6247000-e6247fff : reserved
> e6720000-e690ffff : reserved
> e6a90000-e6a9ffff : reserved
> e6ab0000-e721ffff : reserved
> e7240000-e7240fff : reserved
> fac00000-fafdffff : reserved
> 400040400-40004041f : CAV901C:00
> 400040480-400040567 : CAV901D:00
> 400040480-400040567 : CAV901C:00
> 400040600-40004073b : CAV901E:00
> 400040600-40004073b : CAV901C:00
> 400041400-40004177f : CAV901F:00
> 400041400-40004177f : CAV901C:00
> 402000100-402000fff : CAV9006:00
> 402000100-402000fff : CAV9006:00
> 402020000-40202ffff : ARMH0011:00
> 402020000-40202ffff : ARMH0011:00
> 402300000-40230ffff : arm-smmu-v3.0.auto
> 402300000-40230ffff : arm-smmu-v3.0.auto
> 402320000-40232ffff : arm-smmu-v3.1.auto
> 402320000-40232ffff : arm-smmu-v3.1.auto
> 402340000-40234ffff : arm-smmu-v3.2.auto
> 402340000-40234ffff : arm-smmu-v3.2.auto
> 440040400-44004041f : CAV901C:01
> 440040480-440040567 : CAV901D:01
> 440040480-440040567 : CAV901C:01
> 440040600-44004073b : CAV901E:01
> 440040600-44004073b : CAV901C:01
> 440041400-44004177f : CAV901F:01
> 440041400-44004177f : CAV901C:01
> 4421a0000-4421affff : CAV9007:06
> 4421a0000-4421affff : CAV9007:06
> 442300000-44230ffff : arm-smmu-v3.3.auto
> 442300000-44230ffff : arm-smmu-v3.3.auto
> 442320000-44232ffff : arm-smmu-v3.4.auto
> 442320000-44232ffff : arm-smmu-v3.4.auto
> 442340000-44234ffff : arm-smmu-v3.5.auto
> 442340000-44234ffff : arm-smmu-v3.5.auto
> b81200000-c811fffff : System RAM
> b81280000-b8270ffff : Kernel code
> b82710000-b82dfffff : reserved
> b82e00000-b83168fff : Kernel data
> b83169000-baccd7fff : reserved
> c78a00000-c7fffffff : reserved
> c80129000-c801a9fff : reserved
> c801aa000-c809e9fff : reserved
> c809ec000-c809eefff : reserved
> c809ef000-c811fffff : reserved
> 10000000000-13fffffffff : PCI Bus 0000:00
> 10000000000-100013fffff : PCI Bus 0000:01
> 10000000000-100007fffff : 0000:01:00.0
> 10000800000-10000ffffff : 0000:01:00.1
> 10001000000-1000101ffff : 0000:01:00.0
> 10001020000-1000103ffff : 0000:01:00.1
> 10001040000-1000104ffff : 0000:01:00.0
> 10001050000-1000105ffff : 0000:01:00.1
> 10001400000-100037fffff : PCI Bus 0000:05
> 10001400000-1000140ffff : 0000:05:00.0
> 10001400000-1000140ffff : bnx2x
> 10001410000-1000141ffff : 0000:05:00.1
> 10001410000-1000141ffff : bnx2x
> 10001800000-10001ffffff : 0000:05:00.0
> 10001800000-10001ffffff : bnx2x
> 10002000000-100027fffff : 0000:05:00.0
> 10002000000-100027fffff : bnx2x
> 10002800000-10002ffffff : 0000:05:00.1
> 10002800000-10002ffffff : bnx2x
> 10003000000-100037fffff : 0000:05:00.1
> 10003000000-100037fffff : bnx2x
> 10003800000-100053fffff : PCI Bus 0000:09
> 10003800000-10003ffffff : 0000:09:00.0
> 10003800000-10003ffffff : i40e
> 10004000000-100047fffff : 0000:09:00.1
> 10004000000-100047fffff : i40e
> 10004800000-10004bfffff : 0000:09:00.0
> 10004c00000-10004ffffff : 0000:09:00.1
> 10005000000-10005007fff : 0000:09:00.0
> 10005000000-10005007fff : i40e
> 10005008000-1000500ffff : 0000:09:00.1
> 10005008000-1000500ffff : i40e
> 10005010000-1000510ffff : 0000:09:00.0
> 10005110000-1000520ffff : 0000:09:00.1
> 10005400000-1000540ffff : 0000:00:0f.0
> 10005400000-1000540ffff : xhci-hcd
> 10005410000-1000541ffff : 0000:00:0f.0
> 10005420000-1000542ffff : 0000:00:0f.1
> 10005420000-1000542ffff : xhci-hcd
> 10005430000-1000543ffff : 0000:00:0f.1
> 10005440000-1000544ffff : 0000:00:10.0
> 10005440000-1000544ffff : ahci
> 10005450000-1000545ffff : 0000:00:10.1
> 10005450000-1000545ffff : ahci
> 14000000000-17fffffffff : PCI Bus 0000:80
>
>
> failure with crashkernel=1G
>
> :~$ dmesg | grep crash
> [ 0.000000] cannot allocate crashkernel (size:0x40000000)
> [ 0.000000] Kernel command line: BOOT_IMAGE=/boot/vmlinuz-5.6.0-rc4+
> root=UUID=866b8df3-14f4-4e11-95a1-74a90ee9b694 ro nowatchdog earlycon
> crashkernel=1G crashkernel=250M,low
> [ 29.326916] crashkernel=250M,low
>

I read these clearly, found that your all testcases failed including
"crashkernel=4G@0xb81200000 crashkernel=250M,low".

There is no "Crash kernel (low)" in all your tests, that is there is no enough
low memory, in these cases, parameters equal to 4G@0xb81200000, crashkernel=4G
and crashkernel=1G.

crashkernel=4G and crashkernel=1G all failed because there is no low memory.

Thanks,
Chen Zhou

> --pk
>
> .
>