On Tue, 22 Sep 2015 19:48:14 +0800 Baoquan He <b...@redhat.com> wrote:
> People reported that when allocating crashkernel memory using
> ",high" and ",low" syntax, there were cases where the reservation
> of the "high" portion succeeds, but the reservation of the "low"
> portion fails. Then kexec can load kdump kernel successfully, but
> the boot of kdump kernel fails as there's no low memory. This is
> because allocation of low memory for kdump kernel can fail on large
> systems for reasons. E.g it could be manually specified crashkernel
> low memory is too large to find in memblock region.
>
> In this patch add return value for reserve_crashkernel_low. Then
> try to reserve crashkernel low memory after crashkernel high memory
> has been allocated. If crashkernel low memory reservation failed
> free crashkernel high memory and return. User can take measures
> when they found kdump kernel cann't be loaded successfully.
>
> ...
>
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -493,7 +493,7 @@ static void __init
> memblock_x86_reserve_range_setup_data(void)
> # define CRASH_KERNEL_ADDR_HIGH_MAX MAXMEM
> #endif
>
> -static void __init reserve_crashkernel_low(void)
> +static int __init reserve_crashkernel_low(void)
> {
> #ifdef CONFIG_X86_64
> const unsigned long long alignment = 16<<20; /* 16M */
> @@ -522,17 +522,15 @@ static void __init reserve_crashkernel_low(void)
> } else {
> /* passed with crashkernel=0,low ? */
> if (!low_size)
> - return;
> + return 0;
What's happening here? It's returning "success" when
parse_crashkernel_low() fails?
> }
>
> low_base = memblock_find_in_range(low_size, (1ULL<<32),
> low_size, alignment);
>
> if (!low_base) {
> - if (!auto_set)
> - pr_info("crashkernel low reservation failed - No
> suitable area found.\n");
> -
> - return;
> + pr_info("crashkernel low reservation failed - No suitable area
> found.\n");
That's not a terribly useful message. If kdump is now unavailable and
the operator needs to take some remedial action then we should inform
them of this.
Also, such a message should have higher severity than KERN_INFO?
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