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SubjectRe: [PATCH 1/3] context_tracking: Protect against recursion
On 04/02/2015 01:39 PM, Frederic Weisbecker wrote:
> Context tracking recursion can happen when an exception triggers in the
> middle of a call to a context tracking probe.
>
> This special case can be caused by vmalloc faults. If an access to a
> memory area allocated by vmalloc happens in the middle of
> context_tracking_enter(), we may run into an endless fault loop because
> the exception in turn calls context_tracking_enter() which faults on
> the same vmalloc'ed memory, triggering an exception again, etc...
>
> Some rare crashes have been reported so lets protect against this with
> a recursion counter.
>
> Reported-by: Dave Jones <davej@redhat.com>
> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Rik van Riel <riel@redhat.com>
> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> Cc: Ingo Molnar <mingo@kernel.org>
> Cc: Dave Jones <davej@redhat.com>
> Cc: Oleg Nesterov <oleg@redhat.com>

Reviewed-by: Rik van Riel <riel@redhat.com>



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