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

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

[gregkh]

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 <stable@vger.kernel.org>.

thanks,

greg k-h

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

>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: [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: <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>

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index c0a772560ab7..298dd745651e 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -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)

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

[Suzuki K Poulose]

On 17/08/16 13:51, gregkh@linuxfoundation.org wrote:
>
> 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 <stable@vger.kernel.org>.


Greg,

I will send the backported version for 4.4 soon.

Thanks
Suzuki


>
> thanks,
>
> greg k-h
>
> ------------------ original commit in Linus's tree ------------------
>
> 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: [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: <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>
>
> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> index c0a772560ab7..298dd745651e 100644
> --- a/arch/arm64/kernel/smp.c
> +++ b/arch/arm64/kernel/smp.c
> @@ -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)
>