Patch "arm64: Fix incorrect per-cpu usage for boot CPU" has been added to the 4.4-stable tree

Patch "arm64: Fix incorrect per-cpu usage for boot CPU" has been added to the 4.4-stable tree

[gregkh]

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

    arm64: Fix incorrect per-cpu usage for boot CPU

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:
     arm64-fix-incorrect-per-cpu-usage-for-boot-cpu.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@vger.kernel.org> know about it.


>From 9113c2aa05e9848cd4f1154abee17d4f265f012d Mon Sep 17 00:00:00 2001
From: Suzuki K Poulose <suzuki.poulose@arm.com>
Date: Thu, 21 Jul 2016 11:12:55 +0100
Subject: arm64: Fix incorrect per-cpu usage for boot CPU

From: Suzuki K Poulose <suzuki.poulose@arm.com>

commit 9113c2aa05e9848cd4f1154abee17d4f265f012d upstream.

In smp_prepare_boot_cpu(), we invoke cpuinfo_store_boot_cpu to  store
the cpuinfo in a per-cpu ptr, before initialising the per-cpu offset for
the boot CPU. This patch reorders the sequence to make sure we initialise
the per-cpu offset before accessing the per-cpu area.

Commit 4b998ff1885eec ("arm64: Delay cpuinfo_store_boot_cpu") fixed the
issue where we modified the per-cpu area even before the kernel initialises
the per-cpu areas, but failed to wait until the boot cpu updated it's
offset.

Fixes: 4b998ff1885e ("arm64: Delay cpuinfo_store_boot_cpu")
Cc: <stable@vger.kernel.org> # 4.4+
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/arm64/kernel/smp.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -333,8 +333,8 @@ void __init smp_cpus_done(unsigned int m
 
 void __init smp_prepare_boot_cpu(void)
 {
-	cpuinfo_store_boot_cpu();
 	set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
+	cpuinfo_store_boot_cpu();
 }
 
 static u64 __init of_get_cpu_mpidr(struct device_node *dn)


Patches currently in stable-queue which might be from suzuki.poulose@arm.com are

queue-4.4/arm64-fix-incorrect-per-cpu-usage-for-boot-cpu.patch