Bug#919019: Interval timers with CLOCK_*_CPUTIME_ID fail to reschedule with 4.19.13-1

[Salvatore Bonaccorso <carnil@debian.org>]

Hi,

On Fri, Jan 11, 2019 at 01:24:22PM -0500, anomie@users.sourceforge.net wrote:
> Package: linux-image-4.19.0-1-amd64
> Version: 4.19.13-1
> 
> The attached test program should print about 100 lines each for "Hit
> CLOCK_MONOTONIC!", "Hit CLOCK_PROCESS_CPUTIME_ID!", and "Hit
> CLOCK_THREAD_CPUTIME_ID!".
> 
> On my laptop running kernel linux-image-4.19.0-1-amd64 version
> 4.19.13-1, however, it prints the ~100 for CLOCK_MONOTONIC but only one
> each for CLOCK_PROCESS_CPUTIME_ID and CLOCK_THREAD_CPUTIME_ID.
> 
> On a VirtualBox virtual machine, freshly installed and dist-upgraded to
> sid, I see the same thing. Downgrading to version 4.19.12-1 from
> https://snapshot.debian.org/package/linux-signed-amd64/4.19.12%2B1/#linux-image-4.19.0-1-amd64_4.19.12-1
> (and rebooting, of course) causes the test program to give the expected
> output.
> 
> I don't know if this was something broken upstream or if it's something
> specific to Debian's kernel package. Please forward upstream if
> appropriate. Thanks!

This is a regression introduced by 0e334db6bb4b ("posix-timers: Fix
division by zero bug") and will be adressed with
https://lore.kernel.org/lkml/20190111133500.840117406@linutronix.de/ .

Adding it already to the sid branch in the packaging repo.

Thanks for reporting!

Regards,
Salvatore