mm/memunmap: don't access uninitialized memmap in memunmap_pages()

[platform/kernel/linux-rpi.git] / kernel / memremap.c

diff --git a/kernel/memremap.c b/kernel/memremap.c
index 2ee2e67..1ec1f8f 100644 (file)
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -120,6 +120,7 @@ static void devm_memremap_pages_release(void *data)
        struct device *dev = pgmap->dev;
        struct resource *res = &pgmap->res;
        resource_size_t align_start, align_size;
+       struct page *first_page;
        unsigned long pfn;
        int nid;
 
@@ -132,13 +133,16 @@ static void devm_memremap_pages_release(void *data)
        align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE)
                - align_start;
 
-       nid = page_to_nid(pfn_to_page(align_start >> PAGE_SHIFT));
+       /* make sure to access a memmap that was actually initialized */
+       first_page = pfn_to_page(pfn_first(pgmap));
+
+       nid = page_to_nid(first_page);
 
        mem_hotplug_begin();
        if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
                pfn = align_start >> PAGE_SHIFT;
-               __remove_pages(page_zone(pfn_to_page(pfn)), pfn,
-                               align_size >> PAGE_SHIFT, NULL);
+               __remove_pages(page_zone(first_page), pfn,
+                              align_size >> PAGE_SHIFT, NULL);
        } else {
                arch_remove_memory(nid, align_start, align_size,
                                pgmap->altmap_valid ? &pgmap->altmap : NULL);