Re: Memory exhaustion testing?

[Jesper Dangaard Brouer <brouer@redhat.com>]

On Sat, 14 Nov 2015 17:23:15 +0900
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> wrote:

> On 2015/11/13 5:55, Jesper Dangaard Brouer wrote:
> > Hi MM-people,
> >
> > How do you/we test the error paths when the system runs out of memory?
> >
> > What kind of tools do you use?
> > or Any tricks to provoke this?
> 
> I use SystemTap for injecting memory allocation failure.
> 
> http://lkml.kernel.org/r/201503182136.EJC90660.QSFOVJFOLHFOtM@I-love.SAKURA.ne.jp
> 
> >
> > For testing my recent change to the SLUB allocator, I've implemented a
> > crude kernel module that tries to allocate all memory, so I can test the
> > error code-path in kmem_cache_alloc_bulk.
> >
> > see:
> >   https://github.com/netoptimizer/prototype-kernel/blob/master/kernel/mm/slab_bulk_test04_exhaust_mem.c
> >
> 
> I think you can test the error code-path in kmem_cache_alloc_bulk as
> well.

Yes, making __alloc_pages_nodemask() fail should propagate all the way
back into kmem_cache_alloc_bulk().

I do like your approach, but I think my use-case can be covered by
CONFIG_FAIL_PAGE_ALLOC (which like you, also hook into __alloc_pages_nodemask).
Although it seems I have more control with your approach, to filter in
which situations it should happen in.

Thanks for your input! :-)
-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  Author of http://www.iptv-analyzer.org
  LinkedIn: http://www.linkedin.com/in/brouer

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