[PATCH v1 2/4] mm/memory_hotplug: Make unregister_memory_section() never fail

[David Hildenbrand <david@redhat.com>]

Failing while removing memory is mostly ignored and cannot really be
handled. Let's treat errors in unregister_memory_section() in a nice
way, warning, but continuing.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Banman <andrew.banman@hpe.com>
Cc: "mike.travis@hpe.com" <mike.travis@hpe.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Mathieu Malaterre <malat@debian.org>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 drivers/base/memory.c  | 16 +++++-----------
 include/linux/memory.h |  2 +-
 mm/memory_hotplug.c    |  4 +---
 3 files changed, 7 insertions(+), 15 deletions(-)

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 0c9e22ffa47a..f180427e48f4 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -734,15 +734,18 @@ unregister_memory(struct memory_block *memory)
 {
 	BUG_ON(memory->dev.bus != &memory_subsys);
 
-	/* drop the ref. we got in remove_memory_section() */
+	/* drop the ref. we got via find_memory_block() */
 	put_device(&memory->dev);
 	device_unregister(&memory->dev);
 }
 
-static int remove_memory_section(struct mem_section *section)
+void unregister_memory_section(struct mem_section *section)
 {
 	struct memory_block *mem;
 
+	if (WARN_ON_ONCE(!present_section(section)))
+		return;
+
 	mutex_lock(&mem_sysfs_mutex);
 
 	/*
@@ -763,15 +766,6 @@ static int remove_memory_section(struct mem_section *section)
 
 out_unlock:
 	mutex_unlock(&mem_sysfs_mutex);
-	return 0;
-}
-
-int unregister_memory_section(struct mem_section *section)
-{
-	if (!present_section(section))
-		return -EINVAL;
-
-	return remove_memory_section(section);
 }
 #endif /* CONFIG_MEMORY_HOTREMOVE */
 
diff --git a/include/linux/memory.h b/include/linux/memory.h
index a6ddefc60517..e1dc1bb2b787 100644
--- a/include/linux/memory.h
+++ b/include/linux/memory.h
@@ -113,7 +113,7 @@ extern int register_memory_isolate_notifier(struct notifier_block *nb);
 extern void unregister_memory_isolate_notifier(struct notifier_block *nb);
 int hotplug_memory_register(int nid, struct mem_section *section);
 #ifdef CONFIG_MEMORY_HOTREMOVE
-extern int unregister_memory_section(struct mem_section *);
+extern void unregister_memory_section(struct mem_section *);
 #endif
 extern int memory_dev_init(void);
 extern int memory_notify(unsigned long val, void *v);
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 696ed7ee5e28..b0cb05748f99 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -527,9 +527,7 @@ static int __remove_section(struct zone *zone, struct mem_section *ms,
 	if (!valid_section(ms))
 		return ret;
 
-	ret = unregister_memory_section(ms);
-	if (ret)
-		return ret;
+	unregister_memory_section(ms);
 
 	scn_nr = __section_nr(ms);
 	start_pfn = section_nr_to_pfn((unsigned long)scn_nr);
-- 
2.17.2