Kernel 4.15 lost set_robust_list support on POWER 9

[Florian Weimer]

On 02/05/2018 01:48 PM, Florian Weimer wrote:
> I get this:
> 
> 7041  set_robust_list(0x7fff93dc3980, 24) = -1 ENOSYS (Function not 
> implemented)
> 
> The system call works on 4.14.  Looks like the probing for 
> futex_cmpxchg_enabled goes wrong.
> 
> Sorry, I have no idea where to start digging.  I don't see anything 
> obvious in dmesg.
> 
> I'm trying to revert
> 
> commit 30d6e0a4190d37740e9447e4e4815f06992dd8c3
> Author: Jiri Slaby <jslaby at suse.cz>
> Date:   Thu Aug 24 09:31:05 2017 +0200
> 
>      futex: Remove duplicated code and fix undefined behaviour
> 
> to see if it makes a difference

Never mind, it must be something else because that commit is in 4.14, 
but set_robust_list is still working there.  (Let's hope that the 
probing doesn't fail randomly …)

Thanks,
Florian