mm/memory_hotplug.c: call register_mem_sect_under_node()

When hotplugging memory, it is possible that two calls are being made to
register_mem_sect_under_node().

One comes from __add_section()->hotplug_memory_register() and the other
from add_memory_resource()->link_mem_sections() if we had to register a
new node.

In case we had to register a new node, hotplug_memory_register() will
only handle/allocate the memory_block's since
register_mem_sect_under_node() will return right away because the node
it is not online yet.

I think it is better if we leave hotplug_memory_register() to
handle/allocate only memory_block's and make link_mem_sections() to call
register_mem_sect_under_node().

So this patch removes the call to register_mem_sect_under_node() from
hotplug_memory_register(), and moves the call to link_mem_sections() out
of the condition, so it will always be called.  In this way we only have
one place where the memory sections are registered.

Link: http://lkml.kernel.org/r/20180622111839.10071-3-osalvador@techadventures.net
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Tested-by: Reza Arbab <arbab@linux.vnet.ibm.com>
Tested-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Pasha Tatashin <Pavel.Tatashin@microsoft.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
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 f5e5601..c8a1cb0 100644 (file)
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -736,8 +736,6 @@ int hotplug_memory_register(int nid, struct mem_section *section)
                mem->section_count++;
        }
 
-       if (mem->section_count == sections_per_block)
-               ret = register_mem_sect_under_node(mem, nid, false);
 out:
        mutex_unlock(&mem_sysfs_mutex);
        return ret;

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 504ba12..e2ed64b 100644 (file)
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1123,6 +1123,7 @@ int __ref add_memory_resource(int nid, struct resource *res, bool online)
        u64 start, size;
        bool new_node = false;
        int ret;
+       unsigned long start_pfn, nr_pages;
 
        start = res->start;
        size = resource_size(res);
@@ -1151,34 +1152,23 @@ int __ref add_memory_resource(int nid, struct resource *res, bool online)
        if (ret < 0)
                goto error;
 
-       /* we online node here. we can't roll back from here. */
-       node_set_online(nid);
-
        if (new_node) {
-               unsigned long start_pfn = start >> PAGE_SHIFT;
-               unsigned long nr_pages = size >> PAGE_SHIFT;
-
-               ret = __register_one_node(nid);
-               if (ret)
-                       goto register_fail;
-
-               /*
-                * link memory sections under this node. This is already
-                * done when creatig memory section in register_new_memory
-                * but that depends to have the node registered so offline
-                * nodes have to go through register_node.
-                * TODO clean up this mess.
-                */
-               ret = link_mem_sections(nid, start_pfn, nr_pages, false);
-register_fail:
-               /*
-                * If sysfs file of new node can't create, cpu on the node
+               /* If sysfs file of new node can't be created, cpu on the node
                 * can't be hot-added. There is no rollback way now.
                 * So, check by BUG_ON() to catch it reluctantly..
+                * We online node here. We can't roll back from here.
                 */
+               node_set_online(nid);
+               ret = __register_one_node(nid);
                BUG_ON(ret);
        }
 
+       /* link memory sections under this node.*/
+       start_pfn = start >> PAGE_SHIFT;
+       nr_pages = size >> PAGE_SHIFT;
+       ret = link_mem_sections(nid, start_pfn, nr_pages, false);
+       BUG_ON(ret);
+
        /* create new memmap entry */
        firmware_map_add_hotplug(start, start + size, "System RAM");