Hello, On Mon, Jan 27, 2025 at 04:53:11PM -0800, Andrew Morton wrote: > On Tue, 28 Jan 2025 02:52:50 -0500 sooraj <sooraj20636@xxxxxxxxx> wrote: > > > Ensure cgwb (cgroup writeback) structures are uniquely associated with a > > memcg-blkcg pair to prevent inconsistencies when concurrent cgwb_create > > calls race. This resolves a scenario where two threads creating cgwbs > > for the same memory cgroup (memcg) but different I/O control groups (blkcg) > > could insert conflicting entries. > > > > The fix rechecks for existing cgwbs under the cgwb_lock spinlock after > > initial creation. If a conflicting cgwb (same memcg, different blkcg) is > > found, it is killed before inserting the new entry. This guarantees a > > 1:1 relationship between memcg-blkcg pairs and their cgwbs, preserving > > system invariants. I'm a bit confused. Radix tree doesn't allow two entries to be inserted on the same key and the tree is keyed by memcg_id. Wouldn't that automatically guarantee 1:1 relationship? Thanks. -- tejun
