[FIX PATCH v0] powerpc: Fix memory unplug failure on radix guest

[Reza Arbab]

On Thu, Aug 10, 2017 at 02:53:48PM +0530, Bharata B Rao wrote:
>diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
>index f830562..24ecf53 100644
>--- a/arch/powerpc/kernel/prom.c
>+++ b/arch/powerpc/kernel/prom.c
>@@ -524,6 +524,7 @@ static int __init early_init_dt_scan_drconf_memory(unsigned long node)
> 					size = 0x80000000ul - base;
> 			}
> 			memblock_add(base, size);
>+			memblock_mark_hotplug(base, size);
> 		} while (--rngs);
> 	}
> 	memblock_dump_all();

Doing this has the effect of putting all the affected memory into 
ZONE_MOVABLE. See find_zone_movable_pfns_for_nodes(). This means no 
kernel allocations can occur there. Is that okay?

>diff --git a/arch/powerpc/mm/pgtable-radix.c b/arch/powerpc/mm/pgtable-radix.c
>index 671a45d..180d25a 100644
>--- a/arch/powerpc/mm/pgtable-radix.c
>+++ b/arch/powerpc/mm/pgtable-radix.c
>@@ -12,6 +12,7 @@
> #include <linux/memblock.h>
> #include <linux/of_fdt.h>
> #include <linux/mm.h>
>+#include <linux/memory.h>
>
> #include <asm/pgtable.h>
> #include <asm/pgalloc.h>
>@@ -255,15 +256,25 @@ static void __init radix_init_pgtable(void)
> {
> 	unsigned long rts_field;
> 	struct memblock_region *reg;
>+	phys_addr_t addr;
>+	u64 lmb_size = memory_block_size_bytes();
>
> 	/* We don't support slb for radix */
> 	mmu_slb_size = 0;
> 	/*
> 	 * Create the linear mapping, using standard page size for now
> 	 */
>-	for_each_memblock(memory, reg)
>-		WARN_ON(create_physical_mapping(reg->base,
>-						reg->base + reg->size));
>+	for_each_memblock(memory, reg) {
>+		if (memblock_is_hotpluggable(reg)) {
>+			for (addr = reg->base; addr < (reg->base + reg->size);
>+				addr += lmb_size)
>+				WARN_ON(create_physical_mapping(addr,
>+					addr + lmb_size));
>+		} else {
>+			WARN_ON(create_physical_mapping(reg->base,
>+							reg->base + reg->size));
>+		}
>+	}
>
> 	/* Find out how many PID bits are supported */
> 	if (cpu_has_feature(CPU_FTR_HVMODE)) {
>-- 
>2.7.4
>

-- 
Reza Arbab