x86/mm: Remove the redundant conditional check

In commit f70029bbaacbfa8f0 ("mm, memory_hotplug: drop CONFIG_MOVABLE_NODE"), the dependency on CONFIG_MOVABLE_NODE was removed for N_MEMORY, so the conditional check in paging_init() doesn't make any sense any more. Remove it.

Signed-off-by Baoquan He <[email protected]>

---
 arch/x86/mm/init_64.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

arch/x86/mm/init_64.c +1 -2

index abbdecb75fad..0a14711d3a93 100644
@@ -818,8 +818,7 @@ void __init paging_init(void)
 	 *	 will not set it back.
 	 */
 	node_clear_state(0, N_MEMORY);
-	if (N_MEMORY != N_NORMAL_MEMORY)
-		node_clear_state(0, N_NORMAL_MEMORY);
+	node_clear_state(0, N_NORMAL_MEMORY);
 
 	zone_sizes_init();
 }

Signature · 1 line

2.17.2

Quoted 4 lines · Baoquan He

In commit f70029bbaacbfa8f0 ("mm, memory_hotplug: drop CONFIG_MOVABLE_NODE"), the dependency on CONFIG_MOVABLE_NODE was removed for N_MEMORY, so the conditional check in paging_init() doesn't make any sense any more. Remove it.

Please expand more. I would really have to refresh the intention of the code but from a quick look at the code CONFIG_HIGHMEM still makes N_MEMORY != N_NORMAL_MEMORY. So what what does this change mean for that config?

Quoted 10 lines · Michal Hocko

Quoted 4 lines · Baoquan He

In commit f70029bbaacbfa8f0 ("mm, memory_hotplug: drop CONFIG_MOVABLE_NODE"), the dependency on CONFIG_MOVABLE_NODE was removed for N_MEMORY, so the conditional check in paging_init() doesn't make any sense any more. Remove it.

Please expand more. I would really have to refresh the intention of the code but from a quick look at the code CONFIG_HIGHMEM still makes N_MEMORY != N_NORMAL_MEMORY. So what what does this change mean for that config?

Thanks for looking into this. I was trying to explain that CONFIG_MOVABLE_NODE made N_MEMORY have chance to take different enum value.

Do you think the below saying is OK to you?

~~~
In commit f70029bbaacb ("mm, memory_hotplug: drop CONFIG_MOVABLE_NODE"), the dependency on CONFIG_MOVABLE_NODE was removed for N_MEMORY. Before commit f70029bbaacb, CONFIG_HIGHMEM && !CONFIG_MOVABLE_NODE could make (N_MEMORY == N_NORMAL_MEMORY) be true. After commit f70029bbaacb, N_MEMORY doesn't have any chance to be equal to N_NORMAL_MEMORY. So the conditional check in paging_init() doesn't make any sense any more. Let's remove it.

Quoted 18 lines · Baoquan He

Quoted 10 lines · Michal Hocko

Quoted 4 lines · Baoquan He

In commit f70029bbaacbfa8f0 ("mm, memory_hotplug: drop CONFIG_MOVABLE_NODE"), the dependency on CONFIG_MOVABLE_NODE was removed for N_MEMORY, so the conditional check in paging_init() doesn't make any sense any more. Remove it.

Please expand more. I would really have to refresh the intention of the code but from a quick look at the code CONFIG_HIGHMEM still makes N_MEMORY != N_NORMAL_MEMORY. So what what does this change mean for that config?

Thanks for looking into this. I was trying to explain that CONFIG_MOVABLE_NODE made N_MEMORY have chance to take different enum value.

Do you think the below saying is OK to you?

Quoted 7 lines

~~~
In commit f70029bbaacb ("mm, memory_hotplug: drop CONFIG_MOVABLE_NODE"), the dependency on CONFIG_MOVABLE_NODE was removed for N_MEMORY. Before commit f70029bbaacb, CONFIG_HIGHMEM && !CONFIG_MOVABLE_NODE could make (N_MEMORY == N_NORMAL_MEMORY) be true. After commit f70029bbaacb, N_MEMORY doesn't have any chance to be equal to N_NORMAL_MEMORY. So the conditional check in paging_init() doesn't make any sense any more. Let's remove it.

Yes this describes the matter much better. I have obviously misread the code when looking at it this morning. Being explicit in the changelog would have helped at least me. Thanks!