memory-hotplug: use dev_online for memhp_auto_online

Commit 31bc385 ("add automatic onlining policy for the newly added memory") provides the capability to have added memory automatically onlined during add, but this appears to be slightly broken. The current implementation uses walk_memory_range() to call online_memory_block, which uses memory_block_change_state() to online the memory. Instead, we should be calling device_online() for the memory block in online_memory_block(). This would online the memory (the memory bus online routine memory_subsys_online() called from device_online calls memory_block_change_state()) and properly update the device struct offline flag. As a result of the current implementation, attempting to remove a memory block after adding it using auto online fails. This is because doing a remove, for instance echo offline > /sys/devices/system/memory/memoryXXX/state uses device_offline() which checks the dev->offline flag. Link: http://lkml.kernel.org/r/20170222220744.8119.19687.stgit@ltcalpine2-lp14.aus.stglabs.ibm.com Signed-off-by: Nathan Fontenot <[email protected]> Cc: Michael Ellerman <[email protected]> Cc: Michael Roth <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
wafgo · Feb 25, 2017 · dc18d70 · dc18d70
1 parent dd8416c
commit dc18d70
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Showing 3 changed files with 2 additions and 5 deletions.
diff --git a/drivers/base/memory.c b/drivers/base/memory.c
@@ -249,7 +249,7 @@ memory_block_action(unsigned long phys_index, unsigned long action, int online_t
 	return ret;
 }
 
-int memory_block_change_state(struct memory_block *mem,
+static int memory_block_change_state(struct memory_block *mem,
 		unsigned long to_state, unsigned long from_state_req)
 {
 	int ret = 0;

diff --git a/include/linux/memory.h b/include/linux/memory.h
@@ -109,9 +109,6 @@ 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);
 extern int register_new_memory(int, struct mem_section *);
-extern int memory_block_change_state(struct memory_block *mem,
-				     unsigned long to_state,
-				     unsigned long from_state_req);
 #ifdef CONFIG_MEMORY_HOTREMOVE
 extern int unregister_memory_section(struct mem_section *);
 #endif

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
@@ -1337,7 +1337,7 @@ int zone_for_memory(int nid, u64 start, u64 size, int zone_default,
 
 static int online_memory_block(struct memory_block *mem, void *arg)
 {
-	return memory_block_change_state(mem, MEM_ONLINE, MEM_OFFLINE);
+	return device_online(&mem->dev);
 }
 
 /* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */