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Subject: Re: [PATCH v3 2.6.39-rc1-tip 15/26] 15: uprobes: Handing int3 and
 singlestep exception.
From: Steven Rostedt <rostedt@goodmis.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>, Ingo Molnar <mingo@elte.hu>,
        Linux-mm <linux-mm@kvack.org>,
        Arnaldo Carvalho de Melo <acme@infradead.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Christoph Hellwig <hch@infradead.org>,
        Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
        Oleg Nesterov <oleg@redhat.com>, LKML <linux-kernel@vger.kernel.org>,
        SystemTap <systemtap@sources.redhat.com>,
        Jim Keniston <jkenisto@linux.vnet.ibm.com>,
        Roland McGrath <roland@hack.frob.com>,
        Andi Kleen <andi@firstfloor.org>,
        Andrew Morton <akpm@linux-foundation.org>
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Date: Tue, 19 Apr 2011 09:12:21 -0400
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On Tue, 2011-04-19 at 15:03 +0200, Peter Zijlstra wrote:
> On Fri, 2011-04-01 at 20:05 +0530, Srikar Dronamraju wrote:
> > +       if (unlikely(!utask)) {
> > +               utask = add_utask();
> > +
> > +               /* Failed to allocate utask for the current task. */
> > +               BUG_ON(!utask);
> 
> That's not really nice is it ;-) means I can make the kernel go BUG by
> simply applying memory pressure.

Agreed,

None of these patches should have a single BUG_ON(). They all must fail
nicely.

-- Steve

> 
> > +               utask->state = UTASK_BP_HIT;
> > +       } 


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