Patch "sched: Fix crash in sched_init_numa()" has been added to the 4.4-stable tree

[gregkh at linuxfoundation.org]

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

    sched: Fix crash in sched_init_numa()

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:
     sched-fix-crash-in-sched_init_numa.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 <stable at vger.kernel.org> know about it.


>From 9c03ee147193645be4c186d3688232fa438c57c7 Mon Sep 17 00:00:00 2001
From: Raghavendra K T <raghavendra.kt at linux.vnet.ibm.com>
Date: Sat, 16 Jan 2016 00:31:23 +0530
Subject: sched: Fix crash in sched_init_numa()

From: Raghavendra K T <raghavendra.kt at linux.vnet.ibm.com>

commit 9c03ee147193645be4c186d3688232fa438c57c7 upstream.

The following PowerPC commit:

  c118baf80256 ("arch/powerpc/mm/numa.c: do not allocate bootmem memory for non existing nodes")

avoids allocating bootmem memory for non existent nodes.

But when DEBUG_PER_CPU_MAPS=y is enabled, my powerNV system failed to boot
because in sched_init_numa(), cpumask_or() operation was done on
unallocated nodes.

Fix that by making cpumask_or() operation only on existing nodes.

[ Tested with and w/o DEBUG_PER_CPU_MAPS=y on x86 and PowerPC. ]

Reported-by: Jan Stancek <jstancek at redhat.com>
Tested-by: Jan Stancek <jstancek at redhat.com>
Signed-off-by: Raghavendra K T <raghavendra.kt at linux.vnet.ibm.com>
Cc: <gkurz at linux.vnet.ibm.com>
Cc: <grant.likely at linaro.org>
Cc: <nikunj at linux.vnet.ibm.com>
Cc: <vdavydov at parallels.com>
Cc: <linuxppc-dev at lists.ozlabs.org>
Cc: <linux-mm at kvack.org>
Cc: <peterz at infradead.org>
Cc: <benh at kernel.crashing.org>
Cc: <paulus at samba.org>
Cc: <mpe at ellerman.id.au>
Cc: <anton at samba.org>
Link: http://lkml.kernel.org/r/1452884483-11676-1-git-send-email-raghavendra.kt@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo at kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>

---
 kernel/sched/core.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6738,7 +6738,7 @@ static void sched_init_numa(void)
 
 			sched_domains_numa_masks[i][j] = mask;
 
-			for (k = 0; k < nr_node_ids; k++) {
+			for_each_node(k) {
 				if (node_distance(j, k) > sched_domains_numa_distance[i])
 					continue;
 


Patches currently in stable-queue which might be from raghavendra.kt at linux.vnet.ibm.com are

queue-4.4/sched-fix-crash-in-sched_init_numa.patch