On Tue, Nov 7, 2023 at 11:49 PM Vlastimil Babka <vbabka@xxxxxxx> wrote: > > On 11/8/23 02:28, Sergey Senozhatsky wrote: > > On (23/11/07 15:08), Ankur Arora wrote: > > [..] > >> +++ b/mm/zsmalloc.c > >> @@ -2029,7 +2029,6 @@ static unsigned long __zs_compact(struct zs_pool *pool, > >> dst_zspage = NULL; > >> > >> spin_unlock(&pool->lock); > >> - cond_resched(); > >> spin_lock(&pool->lock); > >> } > >> } > > > > I'd personally prefer to have a comment explaining why we do that > > spin_unlock/spin_lock sequence, which may look confusing to people. > > Wonder if it would make sense to have a lock operation that does the > unlock/lock as a self-documenting thing, and maybe could also be optimized > to first check if there's a actually a need for it (because TIF_NEED_RESCHED > or lock is contended). +1, I was going to suggest this as well. It can be extended to other locking types that disable preemption as well like RCU. Something like spin_lock_relax() or something. > > > Maybe would make sense to put a nice comment in all similar cases. > > For instance: > > > > rcu_read_unlock(); > > - cond_resched(); > > rcu_read_lock(); > >
