Messages in this thread | | | Date | Wed, 2 Apr 2008 18:15:52 +0200 | From | "Vegard Nossum" <> | Subject | Re: kmemcheck caught read from freed memory (cfq_free_io_context) |
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On Wed, Apr 2, 2008 at 6:08 PM, Paul E. McKenney <paulmck@linux.vnet.ibm.com> wrote: > On Wed, Apr 02, 2008 at 02:01:13PM +0300, Pekka Enberg wrote: > > No, kmemcheck is work in progress and does not know about > > SLAB_DESTROY_BY_RCU yet. The reason I asked Vegard to post the warning > > was because Peter, Vegard, and myself identified this particular > > warning as a real problem. But yeah, kmemcheck can cause false > > positives for RCU for now. > > Would the following be an appropriate fix? It seems to me to be in > the same spirit as the existing check for s->ctor.
In my opinion, no.
It would fix the false positives, but would in fact also hide cases such as this one with cfq, e.g. the real cases of mis-use.
Peter Zijlstra suggested this: > It would have to register an call_rcu callback itself in order to mark > it freed - and handle the race with the object being handed out again.
I will try to look into this -- for now, I need to understand RCU first (I've seen your LWN articles -- great work! :-))
Kind regards, Vegard Nossum
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