Re: How to report kernel panic in 4.4.x

[Greg KH]

On Fri, Aug 24, 2018 at 06:19:19PM +0200, Matthias B. wrote:
> Bisect identified the problem. It's the attached patch. I applied it to
> 4.4.152 with patch -Rp1 and I'm running the resulting kernel now.
> 
> MSB
> 
> -- 
> For every idiot-proof system there exists at least one system-proof
> idiot.
> 

> >From 02ff2769edbce2261e981effbc3c4b98fae4faf0 Mon Sep 17 00:00:00 2001
> From: Andi Kleen <ak@xxxxxxxxxxxxxxx>
> Date: Tue, 7 Aug 2018 15:09:39 -0700
> Subject: [PATCH] x86/mm/pat: Make set_memory_np() L1TF safe
> 
> commit 958f79b9ee55dfaf00c8106ed1c22a2919e0028b upstream
> 
> set_memory_np() is used to mark kernel mappings not present, but it has
> it's own open coded mechanism which does not have the L1TF protection of
> inverting the address bits.
> 
> Replace the open coded PTE manipulation with the L1TF protecting low level
> PTE routines.
> 
> Passes the CPA self test.
> 
> Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> [ dwmw2: Pull in pud_mkhuge() from commit a00cc7d9dd, and pfn_pud() ]
> Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
> [groeck: port to 4.4]
> Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> ---
>  arch/x86/include/asm/pgtable.h | 27 +++++++++++++++++++++++++++
>  arch/x86/mm/pageattr.c         |  8 ++++----
>  2 files changed, 31 insertions(+), 4 deletions(-)

<snip>

Guenter, another report of this patch causing an issue.  Any ideas?  I
am away from test systems this weekend, but can push out patches if
needed.

thanks,

greg k-h