On Mon, Aug 12, 2019 at 07:10:52PM +0900, Byungchul Park wrote: > On Sun, Aug 11, 2019 at 04:49:39PM -0700, Paul E. McKenney wrote: > > Maybe. Note well that I said "potential issue". When I checked a few > > years ago, none of the uses of rcu_barrier() cared about kfree_rcu(). > > They cared instead about call_rcu() callbacks that accessed code or data > > that was going to disappear soon, for example, due to module unload or > > filesystem unmount. > > > > So it -might- be that rcu_barrier() can stay as it is, but with changes > > as needed to documentation. Right, we should update the docs. Byungchul, do you mind sending a patch that documents the rcu_barrier() behavior? > > It also -might- be, maybe now or maybe some time in the future, that > > there will need to be a kfree_rcu_barrier() or some such. But if so, > > let's not create it until it is needed. For one thing, it is reasonably > > likely that something other than a kfree_rcu_barrier() would really > > be what was needed. After all, the main point would be to make sure > > that the old memory really was freed before allocating new memory. > > Now I fully understand what you meant thanks to you. Thank you for > explaining it in detail. > > > But if the system had ample memory, why wait? In that case you don't > > really need to wait for all the old memory to be freed, but rather for > > sufficient memory to be available for allocation. > > Agree. Totally make sense. Agreed, all makes sense. thanks, - Joel [snip]
