On Fri, Jun 12, 2020 at 3:28 AM Xiaoming Ni <nixiaom...@huawei.com> wrote: > > Cred release and usage check code flow: > 1. put_cred() > if (atomic_dec_and_test(&(cred)->usage)) > __put_cred(cred); > > 2. __put_cred() > BUG_ON(atomic_read(&cred->usage) != 0); > call_rcu(&cred->rcu, put_cred_rcu); > > 3. put_cred_rcu() > if (atomic_read(&cred->usage) != 0) > panic("CRED: put_cred_rcu() sees %p with usage %d\n", > cred, atomic_read(&cred->usage)); > kmem_cache_free(cred_jar, cred); > > If panic is triggered on put_cred_rcu(), there are two possibilities > 1. Call get_cred() after __put_cred(), usage > 0 > 2. Call put_cred() after __put_cred(), usage < 0 > Since put_cred_rcu is an asynchronous behavior, it is no longer the first > scene when panic, there is no information about the murderer in the panic > call stack... > > So, add WARN() in get_cred()/put_cred(), and pray to catch the murderer > at the first scene. > > Signed-off-by: Xiaoming Ni <nixiaom...@huawei.com> > ---
It seems you reinvented refcount_t ?