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Commit 892365ab authored by Gerald Schaefer's avatar Gerald Schaefer Committed by Martin Schwidefsky
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[S390] memory hotplug: prevent memory zone interleave 



This fixes a kernel oops with CONFIG_DEBUG_VM triggered by a
VM_BUG_ON(bad_range()): kernel BUG at mm/page_alloc.c:748.

With memory hotplug on System z, it is possible that the memory
online/offline state is preserved over a system restart, e.g. there
may be offline memory blocks in ZONE_DMA or ZONE_NORMAL. So far,
the offline memory range has always been added to ZONE_MOVABLE during
system start, so that it was possible to have ZONE_MOVABLE interleave
with ZONE_DMA or ZONE_NORMAL. This patch fixes that by checking for
zone overlap before adding memory.

Signed-off-by: default avatarGerald Schaefer <gerald.schaefer@de.ibm.com>
Reviewed-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent d60331ac

arch/s390/mm/init.c

+26 −4
Original line number Original line Diff line number Diff line
@@ -223,16 +223,38 @@ void free_initrd_mem(unsigned long start, unsigned long end) 
#ifdef CONFIG_MEMORY_HOTPLUG

#ifdef CONFIG_MEMORY_HOTPLUG

int arch_add_memory(int nid, u64 start, u64 size)

int arch_add_memory(int nid, u64 start, u64 size)

{

{

	struct pglist_data *pgdat;

	unsigned long zone_start_pfn, zone_end_pfn, nr_pages;

	unsigned long start_pfn = PFN_DOWN(start);

	unsigned long size_pages = PFN_DOWN(size);

	struct zone *zone;

	struct zone *zone;

	int rc;

	int rc;





	pgdat = NODE_DATA(nid);

	zone = pgdat->node_zones + ZONE_MOVABLE;

	rc = vmem_add_mapping(start, size);

	rc = vmem_add_mapping(start, size);

	if (rc)

	if (rc)

		return rc;

		return rc;

	rc = __add_pages(nid, zone, PFN_DOWN(start), PFN_DOWN(size));

	for_each_zone(zone) {

		if (zone_idx(zone) != ZONE_MOVABLE) {

			/* Add range within existing zone limits */

			zone_start_pfn = zone->zone_start_pfn;

			zone_end_pfn = zone->zone_start_pfn +

				       zone->spanned_pages;

		} else {

			/* Add remaining range to ZONE_MOVABLE */

			zone_start_pfn = start_pfn;

			zone_end_pfn = start_pfn + size_pages;

		}

		if (start_pfn < zone_start_pfn || start_pfn >= zone_end_pfn)

			continue;

		nr_pages = (start_pfn + size_pages > zone_end_pfn) ?

			   zone_end_pfn - start_pfn : size_pages;

		rc = __add_pages(nid, zone, start_pfn, nr_pages);

		if (rc)

			break;

		start_pfn += nr_pages;

		size_pages -= nr_pages;

		if (!size_pages)

			break;

	}

	if (rc)

	if (rc)

		vmem_remove_mapping(start, size);

		vmem_remove_mapping(start, size);

	return rc;

	return rc;