Re: [PATCH v4 3/3] riscv: kdump: Fix crash memory reserve exceed system memory bug

[Mike Rapoport <rppt@kernel.org>]

Hi,

On Mon, Jul 22, 2024 at 11:57:01AM +0800, Jinjie Ruan wrote:
> Similar with x86_32, on Riscv32 Qemu "virt" machine with 1GB memory, the
> crash kernel "crashkernel=4G" is ok as below:
> 	crashkernel reserved: 0x00000000bf400000 - 0x00000001bf400000 (4096 MB)
> 
> The cause is that the crash_size is parsed and printed with "unsigned long
> long" data type which is 8 bytes but allocated used with "phys_addr_t"
> which is 4 bytes in memblock_phys_alloc_range().
> 
> Fix it by checking if the crash_size is greater than system RAM size and
> warn out as parse_crashkernel_mem() do it if so.
> 
> After this patch, it fails and there is no above confusing reserve
> success info.
> 
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
> ---
>  arch/riscv/mm/init.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index bfa2dea95354..5d66a4937fcd 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -1381,6 +1381,11 @@ static void __init arch_reserve_crashkernel(void)
>  	if (ret)
>  		return;
>  
> +	if (crash_size >= memblock_phys_mem_size()) {
> +		pr_warn("Crashkernel: invalid size.");
> +		return;
> +	}
> +

What the point of adding three identical checks right after the call to
parse_crashkernel()?

This check should be there and parse_crashkernel() should return error in
this case.

>  	reserve_crashkernel_generic(cmdline, crash_size, crash_base,
>  				    low_size, high);
>  }
> -- 
> 2.34.1
> 

-- 
Sincerely yours,
Mike.