Patch "mm, meminit: ensure node is online before checking whether pages are uninitialised" 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: ensure node is online before checking whether pages are uninitialised

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-ensure-node-is-online-before-checking-whether-pages-are-uninitialised.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 ef70b6f41cda6270165a6f27b2548ed31cfa3cb2 Mon Sep 17 00:00:00 2001
From: Mel Gorman <mgorman@techsingularity.net>
Date: Thu, 14 Jul 2016 12:07:23 -0700
Subject: mm, meminit: ensure node is online before checking whether pages are uninitialised

From: Mel Gorman <mgorman@techsingularity.net>

commit ef70b6f41cda6270165a6f27b2548ed31cfa3cb2 upstream.

early_page_uninitialised looks up an arbitrary PFN.  While a machine
without node 0 will boot with "mm, page_alloc: Always return a valid
node from early_pfn_to_nid", it works because it assumes that nodes are
always in PFN order.  This is not guaranteed so this patch adds
robustness by always checking if the node being checked is online.

Link: http://lkml.kernel.org/r/1468008031-3848-4-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 |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -286,7 +286,9 @@ static inline void reset_deferred_memini
 /* Returns true if the struct page for the pfn is uninitialised */
 static inline bool __meminit early_page_uninitialised(unsigned long pfn)
 {
-	if (pfn >= NODE_DATA(early_pfn_to_nid(pfn))->first_deferred_pfn)
+	int nid = early_pfn_to_nid(pfn);
+
+	if (node_online(nid) && pfn >= NODE_DATA(nid)->first_deferred_pfn)
 		return true;
 
 	return false;


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