Patch "MIPS: smp.c: Fix uninitialised temp_foreign_map" 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

MIPS: smp.c: Fix uninitialised temp_foreign_map

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:
mips-smp.c-fix-uninitialised-temp_foreign_map.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: James Hogan <[email protected]>
Date: Fri, 4 Mar 2016 10:10:51 +0000
Subject: MIPS: smp.c: Fix uninitialised temp_foreign_map

From: James Hogan <[email protected]>

commit d825c06bfe8b885b797f917ad47365d0e9c21fbb upstream.

When calculate_cpu_foreign_map() recalculates the cpu_foreign_map cpumask it uses the local variable temp_foreign_map without initialising it to zero. Since the calculation only ever sets bits in this cpumask any existing bits at that memory location will remain set and find their way into cpu_foreign_map too. This could potentially lead to cache operations suboptimally doing smp calls to multiple VPEs in the same core, even though the VPEs share primary caches.

Therefore initialise temp_foreign_map using cpumask_clear() before use.

Patchwork: https://patchwork.linux-mips.org/patch/12759/

---
 arch/mips/kernel/smp.c |    1 +
 1 file changed, 1 insertion(+)

@@ -121,6 +121,7 @@ static inline void calculate_cpu_foreign
 	cpumask_t temp_foreign_map;
 
 	/* Re-calculate the mask */
+	cpumask_clear(&temp_foreign_map);
 	for_each_online_cpu(i) {
 		core_present = 0;
 		for_each_cpu(k, &temp_foreign_map)

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

queue-4.4/ld-version-fix-awk-regex-compile-failure.patch queue-4.4/mips-smp.c-fix-uninitialised-temp_foreign_map.patch