mm: skip memory block registration for ZONE_DEVICE

Prevent userspace from trying and failing to online ZONE_DEVICE pages
which are meant to never be onlined.

For example on platforms with a udev rule like the following:

  SUBSYSTEM=="memory", ACTION=="add", ATTR{state}=="offline", ATTR{state}="online"

...will generate futile attempts to online the ZONE_DEVICE sections.
Example kernel messages:

    Built 1 zonelists in Node order, mobility grouping on.  Total pages: 1004747
    Policy zone: Normal
    online_pages [mem 0x248000000-0x24fffffff] failed

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 619fe58..213456c 100644 (file)
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -647,6 +647,13 @@ static int add_memory_block(int base_section_nr)
        return 0;
 }
 
+static bool is_zone_device_section(struct mem_section *ms)
+{
+       struct page *page;
+
+       page = sparse_decode_mem_map(ms->section_mem_map, __section_nr(ms));
+       return is_zone_device_page(page);
+}
 
 /*
  * need an interface for the VM to add new memory regions,
@@ -657,6 +664,9 @@ int register_new_memory(int nid, struct mem_section *section)
        int ret = 0;
        struct memory_block *mem;
 
+       if (is_zone_device_section(section))
+               return 0;
+
        mutex_lock(&mem_sysfs_mutex);
 
        mem = find_memory_block(section);
@@ -693,6 +703,9 @@ static int remove_memory_section(unsigned long node_id,
 {
        struct memory_block *mem;
 
+       if (is_zone_device_section(section))
+               return 0;
+
        mutex_lock(&mem_sysfs_mutex);
        mem = find_memory_block(section);
        unregister_mem_sect_under_nodes(mem, __section_nr(section));

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0ef5f21..d9fe12d 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -674,6 +674,18 @@ static inline enum zone_type page_zonenum(const struct page *page)
        return (page->flags >> ZONES_PGSHIFT) & ZONES_MASK;
 }
 
+#ifdef CONFIG_ZONE_DEVICE
+static inline bool is_zone_device_page(const struct page *page)
+{
+       return page_zonenum(page) == ZONE_DEVICE;
+}
+#else
+static inline bool is_zone_device_page(const struct page *page)
+{
+       return false;
+}
+#endif
+
 #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP)
 #define SECTION_IN_PAGE_FLAGS
 #endif