Re: [PATCH] MIPS: Fix unable to reserve memory for Crash kernel

[Jiaxun Yang <jiaxun.yang@flygoat.com>]

在 2020/7/25 13:56, Jinyang He 写道:
> Use 0 as the align parameter in memblock_find_in_range() is
> incorrect when we reserve memory for Crash kernel.
>
> The environment as follows:
> [    0.000000] MIPS: machine is loongson,loongson64c-4core-rs780e
> ...
> [    1.951016]     crashkernel=64M@128M
>
> The warning as follows:
> [    0.000000] Invalid memory region reserved for crash kernel
>
> And the iomem as follows:
> 00200000-0effffff : System RAM
>    04000000-0484009f : Kernel code
>    048400a0-04ad7fff : Kernel data
>    04b40000-05c4c6bf : Kernel bss
> 1a000000-1bffffff : pci@1a000000
> ...
>
> The align parameter may be finally used by round_down() or round_up().
> Like the following call tree:
>
> mips-next: mm/memblock.c
>
> memblock_find_in_range
> └── memblock_find_in_range_node
>      ├── __memblock_find_range_bottom_up
>      │   └── round_up
>      └── __memblock_find_range_top_down
>          └── round_down
> \#define round_up(x, y) ((((x)-1) | __round_mask(x, y))+1)
> \#define round_down(x, y) ((x) & ~__round_mask(x, y))
> \#define __round_mask(x, y) ((__typeof__(x))((y)-1))
>
> The round_down(or round_up)'s second parameter must be a power of 2.
> If the second parameter is 0, it both will return 0.
>
> Use 1 as the parameter to fix the bug and the iomem as follows:
> 00200000-0effffff : System RAM
>    04000000-0484009f : Kernel code
>    048400a0-04ad7fff : Kernel data
>    04b40000-05c4c6bf : Kernel bss
>    08000000-0bffffff : Crash kernel
> 1a000000-1bffffff : pci@1a000000
> ...
>
> Signed-off-by: Jinyang He <hejinyang@loongson.cn>
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>

Oops, looks like my fault during switch boot_mem_map to memblock.

Thanks.

- Jiaxun

> ---
>   arch/mips/kernel/setup.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
> index 7b537fa..588b212 100644
> --- a/arch/mips/kernel/setup.c
> +++ b/arch/mips/kernel/setup.c
> @@ -497,7 +497,7 @@ static void __init mips_parse_crashkernel(void)
>   	if (ret != 0 || crash_size <= 0)
>   		return;
>   
> -	if (!memblock_find_in_range(crash_base, crash_base + crash_size, crash_size, 0)) {
> +	if (!memblock_find_in_range(crash_base, crash_base + crash_size, crash_size, 1)) {
>   		pr_warn("Invalid memory region reserved for crash kernel\n");
>   		return;
>   	}