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-rw-r--r--mm/memory_hotplug.c38
1 files changed, 38 insertions, 0 deletions
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 02378f11e2d6..3af4d3851d1a 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -308,6 +308,7 @@ static int check_hotplug_memory_addressable(unsigned long pfn,
struct page *pfn_to_online_page(unsigned long pfn)
{
unsigned long nr = pfn_to_section_nr(pfn);
+ struct dev_pagemap *pgmap;
struct mem_section *ms;
if (nr >= NR_MEM_SECTIONS)
@@ -327,6 +328,22 @@ struct page *pfn_to_online_page(unsigned long pfn)
if (!pfn_section_valid(ms, pfn))
return NULL;
+ if (!online_device_section(ms))
+ return pfn_to_page(pfn);
+
+ /*
+ * Slowpath: when ZONE_DEVICE collides with
+ * ZONE_{NORMAL,MOVABLE} within the same section some pfns in
+ * the section may be 'offline' but 'valid'. Only
+ * get_dev_pagemap() can determine sub-section online status.
+ */
+ pgmap = get_dev_pagemap(pfn, NULL);
+ put_dev_pagemap(pgmap);
+
+ /* The presence of a pgmap indicates ZONE_DEVICE offline pfn */
+ if (pgmap)
+ return NULL;
+
return pfn_to_page(pfn);
}
EXPORT_SYMBOL_GPL(pfn_to_online_page);
@@ -709,6 +726,14 @@ static void __meminit resize_pgdat_range(struct pglist_data *pgdat, unsigned lon
pgdat->node_spanned_pages = max(start_pfn + nr_pages, old_end_pfn) - pgdat->node_start_pfn;
}
+
+static void section_taint_zone_device(unsigned long pfn)
+{
+ struct mem_section *ms = __pfn_to_section(pfn);
+
+ ms->section_mem_map |= SECTION_TAINT_ZONE_DEVICE;
+}
+
/*
* Associate the pfn range with the given zone, initializing the memmaps
* and resizing the pgdat/zone data to span the added pages. After this
@@ -739,6 +764,19 @@ void __ref move_pfn_range_to_zone(struct zone *zone, unsigned long start_pfn,
pgdat_resize_unlock(pgdat, &flags);
/*
+ * Subsection population requires care in pfn_to_online_page().
+ * Set the taint to enable the slow path detection of
+ * ZONE_DEVICE pages in an otherwise ZONE_{NORMAL,MOVABLE}
+ * section.
+ */
+ if (zone_is_zone_device(zone)) {
+ if (!IS_ALIGNED(start_pfn, PAGES_PER_SECTION))
+ section_taint_zone_device(start_pfn);
+ if (!IS_ALIGNED(start_pfn + nr_pages, PAGES_PER_SECTION))
+ section_taint_zone_device(start_pfn + nr_pages);
+ }
+
+ /*
* TODO now we have a visible range of pages which are not associated
* with their zone properly. Not nice but set_pfnblock_flags_mask
* expects the zone spans the pfn range. All the pages in the range