On Thu, 19 Jun 2014, Paul E. McKenney wrote: > On Thu, Jun 19, 2014 at 11:32:41PM +0200, Thomas Gleixner wrote: > > > > > > On Thu, 19 Jun 2014, Paul E. McKenney wrote: > > > > > On Thu, Jun 19, 2014 at 10:37:17PM +0200, Thomas Gleixner wrote: > > > > On Thu, 19 Jun 2014, Paul E. McKenney wrote: > > > > > On Thu, Jun 19, 2014 at 09:29:08PM +0200, Thomas Gleixner wrote: > > > > > > On Thu, 19 Jun 2014, Paul E. McKenney wrote: > > > > > > Well, no. Look at the callchain: > > > > > > > > > > > > __call_rcu > > > > > > debug_object_activate > > > > > > rcuhead_fixup_activate > > > > > > debug_object_init > > > > > > kmem_cache_alloc > > > > > > > > > > > > So call rcu activates the object, but the object has no reference in > > > > > > the debug objects code so the fixup code is called which inits the > > > > > > object and allocates a reference .... > > > > > > > > > > OK, got it. And you are right, call_rcu() has done this for a very > > > > > long time, so not sure what changed. But it seems like the right > > > > > approach is to provide a debug-object-free call_rcu_alloc() for use > > > > > by the memory allocators. > > > > > > > > > > Seem reasonable? If so, please see the following patch. > > > > > > > > Not really, you're torpedoing the whole purpose of debugobjects :) > > > > > > > > So, why can't we just init the rcu head when the stuff is created? > > > > > > That would allow me to keep my code unchanged, so I am in favor. ;-) > > > > Almost unchanged. You need to provide a function to do so, i.e. make > > use of > > > > debug_init_rcu_head() > > You mean like this? I'd rather name it init_rcu_head() and free_rcu_head() w/o the debug_ prefix, so it's consistent with init_rcu_head_on_stack / destroy_rcu_head_on_stack. But either way works for me. Acked-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>