Patch "mm, meminit: always return a valid node from early_pfn_to_nid" has been added to the 4.6-stable tree

[<gregkh@linuxfoundation.org>]

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 4.6-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-4.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From e4568d3803852d00effd41dcdd489e726b998879 Mon Sep 17 00:00:00 2001
From: Mel Gorman <mgorman@techsingularity.net>
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 <mgorman@techsingularity.net>

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.

Link: http://lkml.kernel.org/r/1468008031-3848-3-git-send-email-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1110,7 +1110,7 @@ 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 mgorman@techsingularity.net are

queue-4.6/mm-compaction-abort-free-scanner-if-split-fails.patch
queue-4.6/sched-debug-fix-deadlock-when-enabling-sched-events.patch
queue-4.6/mm-compaction-prevent-vm_bug_on-when-terminating-freeing-scanner.patch
queue-4.6/mm-meminit-always-return-a-valid-node-from-early_pfn_to_nid.patch
queue-4.6/mm-meminit-ensure-node-is-online-before-checking-whether-pages-are-uninitialised.patch
queue-4.6/mm-slb-add-__gfp_atomic-to-the-gfp-reclaim-mask.patch