Re: [PATCH v24 3/6] arm64: kdump: Reimplement crashkernel=X

John Donnelly
2022-05-07T17:33:09Z

On 5/6/22 6:10 PM, Baoquan He wrote:
> On 05/06/22 at 07:43pm, Zhen Lei wrote:
> ......
>> @@ -118,8 +162,7 @@ static void __init reserve_crashkernel(void)
>> if (crash_base)
>> crash_max = crash_base + crash_size;
>>
>> - /* Current arm64 boot protocol requires 2MB alignment */
>> - crash_base = memblock_phys_alloc_range(crash_size, SZ_2M,
>> + crash_base = memblock_phys_alloc_range(crash_size, CRASH_ALIGN,
>> crash_base, crash_max);
>> if (!crash_base) {
>> pr_warn("cannot allocate crashkernel (size:0x%llx)\n",
>> @@ -127,6 +170,11 @@ static void __init reserve_crashkernel(void)
>> return;
>> }
>>
>
> There's corner case missed, e.g
> 1) ,high and ,low are specified, CONFIG_ZONE_DMA|DMA32 is not enabled;
> 2) ,high and ,low are specified, the whole system memory is under 4G.
>
> Below judgement can filter them away:
>
> if (crash_base > arm64_dma_phys_limit && crash_low_size &&
> reserve_crashkernel_low(crash_low_size)) {
>
> What's your opinion? Leave it and add document to notice user, or fix it
> with code change >
> I would suggest merging this series, Lei can add this corner case
> handling on top. Since this is a newly added support, we don't have
> to make it one step. Doing step by step can make reviewing easier.

Lets get this added and tested with a broader audience. It has been in
review since March, 4th 2019 - 3+ years. I applaud Zhen for his
endurance and patience in carrying this for so long.

>
>> + if (crash_low_size && 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);
>>
>> @@ -135,6 +183,9 @@ 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
>>
>