Patch "mm, meminit: always return a valid node from early_pfn_to_nid" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

mm, meminit: always return a valid node from early_pfn_to_nid

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
mm-meminit-always-return-a-valid-node-from-early_pfn_to_nid.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Mel Gorman <[email protected]>
Date: Thu, 14 Jul 2016 12:07:20 -0700
Subject: mm, meminit: always return a valid node from early_pfn_to_nid

From: Mel Gorman <[email protected]>

commit e4568d3803852d00effd41dcdd489e726b998879 upstream.

early_pfn_to_nid can return node 0 if a PFN is invalid on machines that has no node 0. A machine with only node 1 was observed to crash with the following message:

   BUG: unable to handle kernel paging request at 000000000002a3c8
   PGD 0
   Modules linked in:
   Hardware name: Supermicro H8DSP-8/H8DSP-8, BIOS 080011  06/30/2006
   task: ffffffff81c0d500 ti: ffffffff81c00000 task.ti: ffffffff81c00000
   RIP: reserve_bootmem_region+0x6a/0xef
   CR2: 000000000002a3c8 CR3: 0000000001c06000 CR4: 00000000000006b0
   Call Trace:
      free_all_bootmem+0x4b/0x12a
      mem_init+0x70/0xa3
      start_kernel+0x25b/0x49b

The problem is that early_page_uninitialised uses the early_pfn_to_nid helper which returns node 0 for invalid PFNs. No caller of early_pfn_to_nid cares except early_page_uninitialised. This patch has early_pfn_to_nid always return a valid node.

---
 mm/page_alloc.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -1057,7 +1057,7 @@ int __meminit early_pfn_to_nid(unsigned
 	spin_lock(&early_pfn_lock);
 	nid = __early_pfn_to_nid(pfn, &early_pfnnid_cache);
 	if (nid < 0)
-		nid = 0;
+		nid = first_online_node;
 	spin_unlock(&early_pfn_lock);
 
 	return nid;

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/mm-compaction-abort-free-scanner-if-split-fails.patch queue-4.4/mm-compaction-prevent-vm_bug_on-when-terminating-freeing-scanner.patch queue-4.4/mm-meminit-always-return-a-valid-node-from-early_pfn_to_nid.patch queue-4.4/mm-meminit-ensure-node-is-online-before-checking-whether-pages-are-uninitialised.patch queue-4.4/mm-slb-add-__gfp_atomic-to-the-gfp-reclaim-mask.patch