On Tue, 2016-09-02 at 03:32:42 UTC, David Gibson wrote:
> This makes a number of cleanups to handling of mapping failures during
> memory hotplug on Power:
>
> For errors creating the linear mapping for the hot-added region:
> * This is now reported with EFAULT which is more appropriate than the
> previous EINVAL (the failure is unlikely to be related to the
> function's parameters)
> * An error in this path now prints a warning message, rather than just
> silently failing to add the extra memory.
> * Previously a failure here could result in the region being partially
> mapped. We now clean up any partial mapping before failing.
>
> For errors creating the vmemmap for the hot-added region:
> * This is now reported with EFAULT instead of causing a BUG() - this
> could happen for external reason (e.g. full hash table) so it's better
> to handle this non-fatally
> * An error message is also printed, so the failure won't be silent
> * As above a failure could cause a partially mapped region, we now
> clean this up.
>
...
> diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
> index baa1a23..fbc9448 100644
> --- a/arch/powerpc/mm/init_64.c
> +++ b/arch/powerpc/mm/init_64.c
> @@ -217,15 +219,20 @@ static void vmemmap_remove_mapping(unsigned long start,
> }
> #endif
> #else /* CONFIG_PPC_BOOK3E */
> -static void __meminit vmemmap_create_mapping(unsigned long start,
> - unsigned long page_size,
> - unsigned long phys)
> +static int __meminit vmemmap_create_mapping(unsigned long start,
> + unsigned long page_size,
> + unsigned long phys)
> {
> - int mapped = htab_bolt_mapping(start, start + page_size, phys,
> - pgprot_val(PAGE_KERNEL),
> - mmu_vmemmap_psize,
> - mmu_kernel_ssize);
> - BUG_ON(mapped < 0);
> + int rc = htab_bolt_mapping(start, start + page_size, phys,
> + pgprot_val(PAGE_KERNEL),
> + mmu_vmemmap_psize, mmu_kernel_ssize);
> + if (rc < 0) {
> + int rc2 = htab_remove_mapping(start, start + page_size,
> + mmu_vmemmap_psize,
> + mmu_kernel_ssize);
This breaks the build when CONFIG_MEMORY_HOTPLUG=n, because
htab_remove_mapping() is not defined.
The obvious fix of moving htab_remove_mapping() out of CONFIG_MEMORY_HOTPLUG
works, so I'll do that unless anyone objects.
cheers
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