On Wed, Feb 07, 2018 at 08:57:00AM -0500, Steven Rostedt wrote: > On Wed, 7 Feb 2018 00:31:04 -0800 > "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx> wrote: > > > I see problems. We would then have two different names for exactly the > > same thing. > > > > Seems like it would be a lot easier to simply document the existing > > kfree_rcu() behavior, especially given that it apparently already works. > > The really doesn't seem to me to be worth a name change. > > Honestly, I don't believe this is an RCU sub-system decision. This is a > memory management decision. > > If we have kmalloc(), vmalloc(), kfree(), vfree() and kvfree(), and we You missed kvmalloc() ... > want kmalloc() to be freed with kfree(), and vmalloc() to be freed with > vfree(), and for strange reasons, we don't know how the data was > allocated we have kvfree(). That's an mm decision not an rcu one. We > should have kfree_rcu(), vfree_rcu() and kvfree_rcu(), and honestly, > they should not depend on kvfree() doing the same thing for everything. > Each should call the corresponding member that they represent. Which > would change this patch set. > > Why? Too much coupling between RCU and MM. What if in the future > something changes and kvfree() goes away or changes drastically. We > would then have to go through all the users of RCU to change them too. > > To me kvfree() is a special case and should not be used by RCU as a > generic function. That would make RCU and MM much more coupled than > necessary. I'd still like it to be called free_rcu() ... so let's turn it around. What memory can you allocate and then *not* free by calling kvfree()? kvfree() can free memory allocated by kmalloc(), vmalloc(), any slab allocation (is that guaranteed, or just something that happens to work?) I think it can't free per-cpu allocations, bootmem, DMA allocations, or alloc_page/get_free_page. Do we need to be able to free any of those objects in order to rename kfree_rcu() to just free_rcu()? -- 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>
