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

Baoquan He
2022-05-06T23:10:45Z

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.

> + 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
>