Messages in this thread | | | Date | Fri, 20 Feb 2009 09:25:26 -0800 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH] mm: fix lazy vmap purging (use-after-free error) |
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On Fri, Feb 20, 2009 at 06:14:27PM +0100, Ingo Molnar wrote: > > * Paul E. McKenney <paulmck@linux.vnet.ibm.com> wrote: > > > > > So, what flavor of RCU were you using? > > > > > > well, even in preemptible RCU the grace period should be > > > extended as long as we are non-preempt (which we are here), > > > correct? > > > > Given Classic RCU, you are quite correct. With preemptable > > RCU, if there are no readers, and if irqs are enabled, the > > grace period could end within the spinlock's critical section. > > Of course, the spinlock would need to be held for an > > improbably long time -- many milliseconds. > > ah. But we _can_ get unlucky there and get into > multiple-milliseconds of blockage: for example if some heavy > interrupt source or softirq processes stuff for many > milliseconds. > > So it's a real fix needed both for mainline and for 2.6.28. > And kudos to kmemcheck ;-)
Kudos from me as well!!! Sure beats the heck out of tracking down memory corruption by hand!!! ;-)
Thanx, Paul
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