Re: [PATCH v21 3/5] arm64: kdump: reimplement crashkernel=X

Leizhen (ThunderTown)
2022-03-17T07:30:14Z

On 2022/3/17 11:47, Baoquan He wrote:
> On 03/17/22 at 11:19am, Leizhen (ThunderTown) wrote:
>>
>>
>> On 2022/3/17 10:36, Baoquan He wrote:
>>> On 03/16/22 at 09:11pm, Leizhen (ThunderTown) wrote:
>>>>
>>>>
>>>> On 2022/3/16 20:11, Baoquan He wrote:
>>>>> On 02/27/22 at 11:07am, Zhen Lei wrote:
>>> ......
>>>
>>>>> 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:
>>>
>>> Considering to update the 3rd line as below:
>>>
>>> * NOTE: Reservation of crashkernel,low is special since its existence
>>> * is not independent, need rely on the existence of crashkernel,high.
>>> * Here, four cases of crashkernel,low reservation are summarized:
>>
>> OK. How about change "crashkernel,low" to "crashkernel low memory"?
>> "crashkernel=Y,low", "crashkernel=,low" and "crashkernel,low" are very similar,
>> may dazzle the reader.
>
> Fine by me. 'crashkernel low memory' is formal, just make sentence a
> little longer. Please take what you think fitter.

OK, I will send v22 after v5.18-rc1.

>
>>
>>>
>>>>> + * 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
>>>>
>>>
>>> .
>>>
>>
>> --
>> Regards,
>> Zhen Lei
>>
>
> .
>

--
Regards,
Zhen Lei