Let's factor out removing of memory block devices, which is only
necessary for memory added via add_memory() and friends that created
memory block devices. Remove the devices before calling
arch_remove_memory().

This finishes factoring out memory block device handling from
arch_add_memory() and arch_remove_memory().

Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <raf...@kernel.org>
Cc: David Hildenbrand <da...@redhat.com>
Cc: "mike.tra...@hpe.com" <mike.tra...@hpe.com>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Andrew Banman <andrew.ban...@hpe.com>
Cc: Ingo Molnar <mi...@kernel.org>
Cc: Alex Deucher <alexander.deuc...@amd.com>
Cc: "David S. Miller" <da...@davemloft.net>
Cc: Mark Brown <broo...@kernel.org>
Cc: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: Oscar Salvador <osalva...@suse.de>
Cc: Jonathan Cameron <jonathan.came...@huawei.com>
Cc: Michal Hocko <mho...@suse.com>
Cc: Pavel Tatashin <pavel.tatas...@microsoft.com>
Cc: Arun KS <aru...@codeaurora.org>
Cc: Mathieu Malaterre <ma...@debian.org>
Reviewed-by: Dan Williams <dan.j.willi...@intel.com>
Signed-off-by: David Hildenbrand <da...@redhat.com>
---
 drivers/base/memory.c  | 37 ++++++++++++++++++-------------------
 drivers/base/node.c    | 11 ++++++-----
 include/linux/memory.h |  2 +-
 include/linux/node.h   |  6 ++----
 mm/memory_hotplug.c    |  5 +++--
 5 files changed, 30 insertions(+), 31 deletions(-)

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 5a0370f0c506..f28efb0bf5c7 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -763,32 +763,31 @@ int create_memory_block_devices(unsigned long start, 
unsigned long size)
        return ret;
 }
 
-void unregister_memory_section(struct mem_section *section)
+/*
+ * Remove memory block devices for the given memory area. Start and size
+ * have to be aligned to memory block granularity. Memory block devices
+ * have to be offline.
+ */
+void remove_memory_block_devices(unsigned long start, unsigned long size)
 {
+       const int start_block_id = pfn_to_block_id(PFN_DOWN(start));
+       const int end_block_id = pfn_to_block_id(PFN_DOWN(start + size));
        struct memory_block *mem;
+       int block_id;
 
-       if (WARN_ON_ONCE(!present_section(section)))
+       if (WARN_ON_ONCE(!IS_ALIGNED(start, memory_block_size_bytes()) ||
+                        !IS_ALIGNED(size, memory_block_size_bytes())))
                return;
 
        mutex_lock(&mem_sysfs_mutex);
-
-       /*
-        * Some users of the memory hotplug do not want/need memblock to
-        * track all sections. Skip over those.
-        */
-       mem = find_memory_block(section);
-       if (!mem)
-               goto out_unlock;
-
-       unregister_mem_sect_under_nodes(mem, __section_nr(section));
-
-       mem->section_count--;
-       if (mem->section_count == 0)
+       for (block_id = start_block_id; block_id != end_block_id; block_id++) {
+               mem = find_memory_block_by_id(block_id, NULL);
+               if (WARN_ON_ONCE(!mem))
+                       continue;
+               mem->section_count = 0;
+               unregister_memory_block_under_nodes(mem);
                unregister_memory(mem);
-       else
-               put_device(&mem->dev);
-
-out_unlock:
+       }
        mutex_unlock(&mem_sysfs_mutex);
 }
 
diff --git a/drivers/base/node.c b/drivers/base/node.c
index 8598fcbd2a17..04fdfa99b8bc 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -801,9 +801,10 @@ int register_mem_sect_under_node(struct memory_block 
*mem_blk, void *arg)
        return 0;
 }
 
-/* unregister memory section under all nodes that it spans */
-int unregister_mem_sect_under_nodes(struct memory_block *mem_blk,
-                                   unsigned long phys_index)
+/*
+ * Unregister memory block device under all nodes that it spans.
+ */
+int unregister_memory_block_under_nodes(struct memory_block *mem_blk)
 {
        NODEMASK_ALLOC(nodemask_t, unlinked_nodes, GFP_KERNEL);
        unsigned long pfn, sect_start_pfn, sect_end_pfn;
@@ -816,8 +817,8 @@ int unregister_mem_sect_under_nodes(struct memory_block 
*mem_blk,
                return -ENOMEM;
        nodes_clear(*unlinked_nodes);
 
-       sect_start_pfn = section_nr_to_pfn(phys_index);
-       sect_end_pfn = sect_start_pfn + PAGES_PER_SECTION - 1;
+       sect_start_pfn = section_nr_to_pfn(mem_blk->start_section_nr);
+       sect_end_pfn = section_nr_to_pfn(mem_blk->end_section_nr);
        for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) {
                int nid;
 
diff --git a/include/linux/memory.h b/include/linux/memory.h
index db3e8567f900..f26a5417ec5d 100644
--- a/include/linux/memory.h
+++ b/include/linux/memory.h
@@ -112,7 +112,7 @@ extern void unregister_memory_notifier(struct 
notifier_block *nb);
 extern int register_memory_isolate_notifier(struct notifier_block *nb);
 extern void unregister_memory_isolate_notifier(struct notifier_block *nb);
 int create_memory_block_devices(unsigned long start, unsigned long size);
-extern void unregister_memory_section(struct mem_section *);
+void remove_memory_block_devices(unsigned long start, unsigned long size);
 extern int memory_dev_init(void);
 extern int memory_notify(unsigned long val, void *v);
 extern int memory_isolate_notify(unsigned long val, void *v);
diff --git a/include/linux/node.h b/include/linux/node.h
index 1a557c589ecb..02a29e71b175 100644
--- a/include/linux/node.h
+++ b/include/linux/node.h
@@ -139,8 +139,7 @@ extern int register_cpu_under_node(unsigned int cpu, 
unsigned int nid);
 extern int unregister_cpu_under_node(unsigned int cpu, unsigned int nid);
 extern int register_mem_sect_under_node(struct memory_block *mem_blk,
                                                void *arg);
-extern int unregister_mem_sect_under_nodes(struct memory_block *mem_blk,
-                                          unsigned long phys_index);
+extern int unregister_memory_block_under_nodes(struct memory_block *mem_blk);
 
 extern int register_memory_node_under_compute_node(unsigned int mem_nid,
                                                   unsigned int cpu_nid,
@@ -176,8 +175,7 @@ static inline int register_mem_sect_under_node(struct 
memory_block *mem_blk,
 {
        return 0;
 }
-static inline int unregister_mem_sect_under_nodes(struct memory_block *mem_blk,
-                                                 unsigned long phys_index)
+static inline int unregister_memory_block_under_nodes(struct memory_block 
*mem_blk)
 {
        return 0;
 }
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 9a92549ef23b..82136c5b4c5f 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -520,8 +520,6 @@ static void __remove_section(struct zone *zone, struct 
mem_section *ms,
        if (WARN_ON_ONCE(!valid_section(ms)))
                return;
 
-       unregister_memory_section(ms);
-
        scn_nr = __section_nr(ms);
        start_pfn = section_nr_to_pfn((unsigned long)scn_nr);
        __remove_zone(zone, start_pfn);
@@ -1845,6 +1843,9 @@ void __ref __remove_memory(int nid, u64 start, u64 size)
        memblock_free(start, size);
        memblock_remove(start, size);
 
+       /* remove memory block devices before removing memory */
+       remove_memory_block_devices(start, size);
+
        arch_remove_memory(nid, start, size, NULL);
        __release_memory_resource(start, size);
 
-- 
2.20.1

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