Re: [RFC 2/3] futex: exit: Print a warning when futex_cleanup fails

[Nico Pache <npache@redhat.com>]

On 4/21/22 16:53, Thomas Gleixner wrote:
> On Thu, Apr 21 2022 at 15:05, Nico Pache wrote:
> 
>> The futex_cleanup routines currently fails silently.
>>
>> Allow the futex_cleanup routines to fail more verbosely so we can
>> leave a message behind for easier debugging/error detecting.
> 
> This is a free ticket to spam dmesg for any unpriviledged user.
As Matthew pointed out, we'd want to rate limit this. I was also thinking we can
limit this to debug kernels so unpriviledged users can not cause dmesg spamming
in production configs.
> 
>> Fixes: 0771dfefc9e5 ("[PATCH] lightweight robust futexes: core")
> 
> There is nothing to fix, really.
Fair enough, its been part of the design since inceptions.
> 
> Robust futexes are best effort as I explained you before and spamming
> dmesg won't help anything.
It would have helped find the OOM/Robust Futex issue more quickly. It may also
help detect breakages in the pthread code (or any other users of robust futex)
if someone is doing something incorrectly.

Just a thought though. If you think its pointless to proceed down this path I
wont push forward.

Cheers,
-- Nico