[Makedumpfile Patch v2 7/7] mem-usage: allow to work only with -f for kernel version < 4.11

[Atsushi Kumagai]

>Hi Atsushi,
>
>On Thursday 02 March 2017 10:19 AM, Atsushi Kumagai wrote:
>> Hello Pratyush,
>>
>>> PT_LOAD of kcore does not have valid p_paddr values for kernel version
>>> less that v4.11. Therefore, older kernel will no long work for mem-usage
>>> with current makedumpfile code. They can only work when they are patched
>>> with fix to "update physical address for kcore ram and text".
>>>
>>> This patch fixes the makedumpfile so that it does not allow to work
>>> older kernel for --mem-usage until someone is sure that kernel is
>>> rightly patched and so uses -f in command line.
>>>
>>> Signed-off-by: Pratyush Anand <panand at redhat.com>
>>> ---
>>> makedumpfile.c | 6 ++++++
>>> 1 file changed, 6 insertions(+)
>>>
>>> diff --git a/makedumpfile.c b/makedumpfile.c
>>> index 3b8e9810468d..bf006ea5dd5f 100644
>>> --- a/makedumpfile.c
>>> +++ b/makedumpfile.c
>>> @@ -11269,6 +11269,12 @@ main(int argc, char *argv[])
>>> 			MSG("Try `makedumpfile --help' for more information.\n");
>>> 			goto out;
>>> 		}
>>> +		if (info->kernel_version < KERNEL_VERSION(4, 11, 0) &&
>>> +				!info->flag_force) {
>>> +			MSG("mem-usage not supported for this kernel.\n");
>>> +			MSG("You can try with -f if your kernel's kcore has valid p_paddr\n");
>>> +			return COMPLETED;
>>> +		}
>>
>> Should use "goto out" to prevent memory leaks since some heap blocks are
>> allocated at the head of main().
>
>OK
>
>>
>> BTW, the descriptions of -f option in man and print_usage() don't mention this usage:
>>
>>        -f     Force existing DUMPFILE to be overwritten.
>>               Example:
>>               # makedumpfile -f -d 31 -x vmlinux /proc/vmcore dumpfile
>>               This command overwrites DUMPFILE even if it already exists.
>>
>> so they should be updated.
>
>Does following looks fine to you?

looks good to me.
I'll wait for the next version.

Thanks,
Atsushi Kumagai

>$ makedumpfile --help | grep -A3 "\-f"
>   [-f]:
>       Overwrite DUMPFILE even if it already exists
>       Force mem-usage to work with older kernel as well.
>
>
>$ man makedumpfile | grep -w "\-f  " -A6
>        -f     Force existing DUMPFILE to be overwritten and mem-usage
>to work with older kernel as well.
>               Example:
>               # makedumpfile -f -d 31 -x vmlinux /proc/vmcore dumpfile
>               This command overwrites DUMPFILE even if it already exists.
>               # makedumpfile -f --mem-usage /proc/kcore
>               Kernel version lesser than v4.11 will not work with
>--mem-usage functionality until it has been  patched  with  upstream  commit
>               464920104bf7.  Therefore if you have patched your older
>kernel then use -f.
>
>Thanks for the review.
>
>~Pratyush