mm: fix mixed zone detection in devm_memremap_pages

The check for whether we overlap "System RAM" needs to be done at
section granularity.  For example a system with the following mapping:

    100000000-37bffffff : System RAM
    37c000000-837ffffff : Persistent Memory

...is unable to use devm_memremap_pages() as it would result in two
zones colliding within a given section.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Toshi Kani <toshi.kani@hpe.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/kernel/memremap.c b/kernel/memremap.c
index 778191e..60baf4d 100644 (file)
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -270,13 +270,16 @@ struct dev_pagemap *find_dev_pagemap(resource_size_t phys)
 void *devm_memremap_pages(struct device *dev, struct resource *res,
                struct percpu_ref *ref, struct vmem_altmap *altmap)
 {
-       int is_ram = region_intersects(res->start, resource_size(res),
-                       "System RAM");
        resource_size_t key, align_start, align_size, align_end;
        struct dev_pagemap *pgmap;
        struct page_map *page_map;
+       int error, nid, is_ram;
        unsigned long pfn;
-       int error, nid;
+
+       align_start = res->start & ~(SECTION_SIZE - 1);
+       align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE)
+               - align_start;
+       is_ram = region_intersects(align_start, align_size, "System RAM");
 
        if (is_ram == REGION_MIXED) {
                WARN_ONCE(1, "%s attempted on mixed region %pr\n",
@@ -314,8 +317,6 @@ void *devm_memremap_pages(struct device *dev, struct resource *res,
 
        mutex_lock(&pgmap_lock);
        error = 0;
-       align_start = res->start & ~(SECTION_SIZE - 1);
-       align_size = ALIGN(resource_size(res), SECTION_SIZE);
        align_end = align_start + align_size - 1;
        for (key = align_start; key <= align_end; key += SECTION_SIZE) {
                struct dev_pagemap *dup;