FAILED: patch "[PATCH] arm64: Fix incorrect per-cpu usage for boot CPU" failed to apply to 4.4-stable tree

From 9113c2aa05e9848cd4f1154abee17d4f265f012d Mon Sep 17 00:00:00 2001

The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 9113c2aa05e9848cd4f1154abee17d4f265f012d Mon Sep 17 00:00:00 2001
From: Suzuki K Poulose <[email protected]>
Date: Thu, 21 Jul 2016 11:12:55 +0100
Subject: [PATCH] arm64: Fix incorrect per-cpu usage for boot CPU

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 <[email protected]> # 4.4+

Cc Will Deacon <[email protected]>

Signed-off-by Suzuki K Poulose <[email protected]>

Acked-by Mark Rutland <[email protected]>

Signed-off-by Catalin Marinas <[email protected]>

arch/arm64/kernel/smp.c +1 -1

index c0a772560ab7..298dd745651e 100644
@@ -436,9 +436,9 @@ void __init smp_cpus_done(unsigned int max_cpus)
 
 void __init smp_prepare_boot_cpu(void)
 {
+	set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
 	cpuinfo_store_boot_cpu();
 	save_boot_cpu_run_el();
-	set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
 }
 
 static u64 __init of_get_cpu_mpidr(struct device_node *dn)