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

[ats-kumagai@xxxxxxxxxxxxx (Atsushi Kumagai)]

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().

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.


Thanks,
Atsushi Kumagai