On Sat, Mar 15, 2025 at 10:49:23AM -0700, Shakeel Butt wrote: > Currently drain_obj_stock() can potentially call __refill_stock which > accesses local cpu stock and thus requires memcg stock's local_lock. > However if we look at the code paths leading to drain_obj_stock(), there > is never a good reason to refill the memcg stock at all from it. > > At the moment, drain_obj_stock can be called from reclaim, hotplug cpu > teardown, mod_objcg_state() and refill_obj_stock(). For reclaim and > hotplug there is no need to refill. For the other two paths, most > probably the newly switched objcg would be used in near future and thus > no need to refill stock with the older objcg. > > In addition, __refill_stock() from drain_obj_stock() happens on rare > cases, so performance is not really an issue. Let's just uncharge > directly instead of refill which will also decouple drain_obj_stock from > local cpu stock and local_lock requirements. > > Signed-off-by: Shakeel Butt <shakeel.butt@xxxxxxxxx> > Acked-by: Vlastimil Babka <vbabka@xxxxxxx> Reviewed-by: Roman Gushchin <roman.gushchin@xxxxxxxxx>
