On 6/30/25 5:28 AM, Yu Kuai wrote: > From: Yu Kuai <yukuai3@xxxxxxxxxx> > > __xa_cmpxchg() is called with rcu_read_lock(), and it will allocate > memory if necessary. > > Fix the problem by moving rcu_read_lock() after __xa_cmpxchg(), meanwhile, > it still should be held before xa_unlock(), prevent returned page to be > freed by concurrent discard. The rcu locking in there is a bit of a mess, imho. What _exactly_ is the rcu read side locking protecting? Is it only needed around the lookup and insert? We even hold it over the kmap and copy, which seems very heavy handed. -- Jens Axboe
