ACK/cmnt: [PATCH] [SRU] [xenial/master-next] [Config] arm64: disable BPF_JIT_ALWAYS_ON

[Stefan Bader]

On 13.04.2018 11:41, Paolo Pisati wrote:
> BugLink: https://bugs.launchpad.net/bugs/1763644
> 
> [Impact]
> 
> The Ubuntu-4.4.0-120.144 kernel (now in -proposed) fails to boot on all arm64
> hardware: no console output or any other sign of activity, the system freezes
> right after the bootloader loads vmlinuz, and jumps to it.
> 
> We first experienced it on the snapdragon kernel snap in -beta (dragonboard
> 410c) but the bug is arm64 generic, and it affects all the arm64 hardware: a
> thunderx board shows the same exact symptoms.
> 
> The regression came down as part of the 4.4.115 stable update ("79e83d1 bpf:
> introduce BPF_JIT_ALWAYS_ON config") and enabled this option that crashes the
> arm64 kernel on boot.
> 
> [How to test]
> 
> Apply the attached patch, recompile, install and boot.
> 
> [Regression potential]
> 
> None, since the kernel already fails to boot.
> 
> I attached the config change for generic and snapdragon.
> 
> Paolo Pisati (1):
>   UBUNTU: [Config] arm64: disable BPF_JIT_ALWAYS_ON
> 
>  debian.master/config/amd64/config.common.amd64 | 1 +
>  debian.master/config/arm64/config.common.arm64 | 1 +
>  debian.master/config/config.common.ubuntu      | 1 -
>  debian.master/config/s390x/config.common.s390x | 1 +
>  4 files changed, 3 insertions(+), 1 deletion(-)
> 

Just to double check for generic config, let us run updateconfigs after applying
the patch (slightly wondering whether it should propagate into more than just
amd64 and s390x).

-Stefan

Acked-by: Stefan Bader <stefan.bader at canonical.com>


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