Re: [PATCH v4 3.0-rc2-tip 13/22] 13: uprobes: Handing int3 andsinglestep exception.

[Peter Zijlstra]

On Thu, 2011-06-16 at 17:34 +0530, Srikar Dronamraju wrote:
> > > +
> > > +cleanup_ret:
> > > +       if (u) {
> > > +               down_read(&mm->mmap_sem);
> > > +               if (!set_orig_insn(current, u, probept, true))
> > 
> > we try to undo the probe? That doesn't make any sense. I thought you
> > meant to return to userspace, let it re-take the trap and try again
> > until you do manage to allocate the user resource.
> 
> I meant removing the probe itself
> https://lkml.org/lkml/2011/4/21/279
> 
> We could try reseting and retrying the trap. Just that we might end up
> looping under memory pressure.
> 
> > 
> > This behaviour makes probes totally unreliable under memory pressure. 
> 
> Under memory pressure we could be unreliable. 

But that is total crap, there's nothing worse than unreliable debug
tools.


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