[PATCH v5 17/31] powernv/fadump: Warn before processing partial crashdump

[Michael Ellerman]

Hari Bathini <hbathini at linux.ibm.com> writes:
> diff --git a/arch/powerpc/platforms/powernv/opal-fadump.c b/arch/powerpc/platforms/powernv/opal-fadump.c
> index 10f6086..6a05d51 100644
> --- a/arch/powerpc/platforms/powernv/opal-fadump.c
> +++ b/arch/powerpc/platforms/powernv/opal-fadump.c
> @@ -71,6 +71,30 @@ static void opal_fadump_get_config(struct fw_dump *fadump_conf,
>  	 */
>  	fadump_conf->reserve_dump_area_start = fdm->rgn[0].dest;
>  
> +	/*
> +	 * Rarely, but it can so happen that system crashes before all
> +	 * boot memory regions are registered for MPIPL. In such
> +	 * cases, warn that the vmcore may not be accurate and proceed
> +	 * anyway as that is the best bet considering free pages, cache
> +	 * pages, user pages, etc are usually filtered out.
> +	 *
> +	 * Hope the memory that could not be preserved only has pages
> +	 * that are usually filtered out while saving the vmcore.
> +	 */
> +	if (fdm->region_cnt > fdm->registered_regions) {
> +		pr_warn("Not all memory regions are saved as system seems to have crashed before all the memory regions could be registered for MPIPL!\n");

That line is rather long, I mean the actual printed line not the source line.

Also "seems to" is vague, I think better to just state what we know to
be true, ie: "Not all memory regions were saved".

> +		pr_warn("  The below boot memory regions could not be saved:\n");
> +		i = fdm->registered_regions;
> +		while (i < fdm->region_cnt) {
> +			pr_warn("\t%d. base: 0x%llx, size: 0x%llx\n", (i + 1),
> +				fdm->rgn[i].src, fdm->rgn[i].size);
> +			i++;
> +		}
> +
> +		pr_warn("  Wishing for the above regions to have only pages that are usually filtered out (user pages, free pages, etc..) and proceeding anyway..\n");
> +		pr_warn("  But the sanity of the '/proc/vmcore' file depends on whether the above region(s) have any kernel pages or not.\n");

Again those lines are too long for people on small consoles.

And "Wishing" is not really what people want to see when their system
has crashed :)

You should say something more definite, eg:
  "If the unsaved regions only contain pages that are filtered out (eg.
   free/user pages), the vmcore should still be usable. If the unsaved
   regions contain kernel pages the vmcore will be corrupted."

Or something like that.

cheers