Re: [PATCH 1/2] Remove the "mem=" parameter when using the --reuse-cmdline option in kdump operation

[Youling Tang <youling.tang@linux.dev>]

Hi, Dave

On 9/25/25 17:11, Dave Young wrote:
> Hi Youling,
>
> On Thu, 25 Sept 2025 at 14:33, Youling Tang <youling.tang@linux.dev> wrote:
>> From: Youling Tang <tangyouling@kylinos.cn>
>>
>> During kdump operations, the capture kernel cannot reuse the "mem="
>> parameter from the production kernel. The "mem=" parameter is used
>> to specify the available memory range for the kernel. Reusing the
>> "mem=" memory range may destroy the production environment.
>>
>> Signed-off-by: Youling Tang <tangyouling@kylinos.cn>
>> ---
>>   kexec/kexec.c | 4 +++-
>>   1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/kexec/kexec.c b/kexec/kexec.c
>> index c9e4bcb..fadf986 100644
>> --- a/kexec/kexec.c
>> +++ b/kexec/kexec.c
>> @@ -1256,8 +1256,10 @@ char *get_command_line(void)
>>                  *p = '\0';
>>
>>          remove_parameter(line, "BOOT_IMAGE");
>> -       if (kexec_flags & KEXEC_ON_CRASH)
>> +       if (kexec_flags & KEXEC_ON_CRASH) {
>>                  remove_parameter(line, "crashkernel");
>> +               remove_parameter(line, "mem=");
>> +       }
> People can remove it from the kdump load scripts instead if it is not
> useful. I do not suggest removing other cmdline in c code.  The
> crashkernel is a special one which is fine.
Removing it in scripts is also acceptable. However, reusing the 
production kernel's
"mem=" parameter will inevitably damage the production environment. In 
my view,
modifying it in C code can achieve a permanent solution (avoiding the 
need to
modify kdump services for each distribution, and also applicable to 
non-kdump
services scenarios where commands are executed directly).

Thanks,
Youling.
>>          return line;
>>   }
>> --
>> 2.48.1
>>
>>
> Thanks
> Dave
>