Re: [PATCH -next 1/2] riscv: kdump: Implement crashkernel=X,[high,low]

chenjiahao (C)
2023-03-27T12:51:06Z

On 2023/3/20 22:36, Simon Horman wrote:
> On Tue, Mar 21, 2023 at 04:42:43AM +0800, Chen Jiahao wrote:
>> On riscv, the current crash kernel allocation logic is trying to
>> allocate within 32bit addressible memory region by default, if
>> failed, try to allocate without 4G restriction.
>>
>> In need of saving DMA zone memory while allocating a relatively large
>> crash kernel region, allocating the reserved memory top down in
>> high memory, without overlapping the DMA zone, is a mature solution.
>> Here introduce the parameter option crashkernel=X,[high,low].
>>
>> We can reserve the crash kernel from high memory above DMA zone range
>> by explicitly passing "crashkernel=X,high"; or reserve a memory range
>> below 4G with "crashkernel=X,low".
>>
>> Signed-off-by: Chen Jiahao <chenjiahao16@huawei.com>
> Some minor nits, but I don't think there is any need to respin for them.
>
> Reviewed-by: Simon Horman <horms@kernel.org>

I will send another version and clean up these by the way, thanks.

Chen, Jiahao

>
> ...
>
>> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
>> index 478d6763a01a..5def2174b243 100644
>> --- a/arch/riscv/mm/init.c
>> +++ b/arch/riscv/mm/init.c
> ...
>
>> @@ -1201,16 +1242,25 @@ static void __init reserve_crashkernel(void)
>> */
>> crash_base = memblock_phys_alloc_range(crash_size, PMD_SIZE,
>> search_start,
>> - min(search_end, (unsigned long) SZ_4G));
>> + min(search_end, (unsigned long) dma32_phys_limit));
> nit: While here, you could drop the space before 'ma32_phys_limit'.
> Or perhaps use min_t, which seems appropriate here.
>
>> if (crash_base == 0) {
>> /* Try again without restricting region to 32bit addressible memory */
>> crash_base = memblock_phys_alloc_range(crash_size, PMD_SIZE,
>> - search_start, search_end);
>> + search_start, search_end);
>> if (crash_base == 0) {
>> pr_warn("crashkernel: couldn't allocate %lldKB\n",
>> crash_size >> 10);
>> return;
>> }
>> +
>> + if (!crash_low_size)
>> + crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
>> + }
>> +
>> + if ((crash_base > dma32_phys_limit - crash_low_size) &&
>> + crash_low_size && reserve_crashkernel_low(crash_low_size)) {
> nit: The line above should be aligned one character to the left
> (remove one space in the indent).
>
>> + memblock_phys_free(crash_base, crash_size);
>> + return;
>> }
>>
>> pr_info("crashkernel: reserved 0x%016llx - 0x%016llx (%lld MB)\n",
> ...