Re: [LKP] [rcutorture] 3b745c8969: WARNING:at_mm/slab_common.c:#kmalloc_slab

[Joel Fernandes <joel@joelfernandes.org>]

On Thu, Jul 26, 2018 at 04:53:25AM -0700, Paul E. McKenney wrote:
> On Thu, Jul 26, 2018 at 04:50:15PM +0800, kernel test robot wrote:
> > 
> > FYI, we noticed the following commit (built with gcc-5):
> > 
> > commit: 3b745c8969c752601cb68c82a06735363563ab42 ("rcutorture: Make boost test more robust")
> > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
> > 
> > in testcase: boot
> > 
> > on test machine: qemu-system-x86_64 -enable-kvm -smp 2 -m 512M
> > 
> > caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):
> 
> Is this fixed by 4babd855fd61 ("rcutorture: Add support to detect
> if boost kthread prio is too low")?  That could address the
> rcu_torture_stats_print() failures, depending on exactly what they were.
> (Yes, I should have reversed these two commits, but they are in -tip
> now, so that ship has sailed.)
> 
> Joel, any other thoughts?

I ran the next tree myself and was not able to reproduce the issue with the
same configuration. Although I don't have rcupdate.rcu_cpu_stall_timeout=100
passed in like they do (which I can also try if you think its of significance
here).

It seems from their logs that most Locking API self tests are failing. the
Lock API test suite is run before rcutorture where rcutorture hasn't even
started.

Also as per their rcutorture output, it appears the 'rtf' value is also
non-zero (rcu_torture_free test). Which makes sense if the earlier memory
allocation warnings are somehow related.

thanks,

- Joel