On Thu, Jan 18, 2024 at 08:59:55AM -0800, Yosry Ahmed wrote: > On Thu, Jan 18, 2024 at 5:52 AM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote: > > > > On Wed, Jan 17, 2024 at 10:20:29PM -0800, Yosry Ahmed wrote: > > > > /* walk the tree and free everything */ > > > > spin_lock(&tree->lock); > > > > + > > > > + xas_for_each(&xas, e, ULONG_MAX) > > > > > > Why not use xa_for_each? > > > > xas_for_each() is O(n) while xa_for_each() is O(n log n), as mentioned > > in the fine documentation. If you don't need to drop the lock while > > in the body of the loop, always prefer xas_for_each(). > > Thanks for pointing this out. Out of ignorance, I skipped reading the > doc for this one and operated under the general assumption to use xa_* > functions were possible. > > The doc also says we should hold either the RCU read lock or the > xa_lock while iterating, we are not doing either here, no? I have no idea; I haven't studied the patches in detail yet. I have debugging assertions for that, so I was assuming that Chris had been developing with debug options turned on. If not, I guess the bots will do it for him.
