Re: kern/60305 (panic in AIO)

[riastradh%NetBSD.org@localhost]

Synopsis: panic in AIO

Responsible-Changed-From-To: kern-bug-people->christos
Responsible-Changed-By: riastradh%NetBSD.org@localhost
Responsible-Changed-When: Mon, 01 Jun 2026 21:43:06 +0000
Responsible-Changed-Why:
Looks like this bug was introduced in the 2025 overhaul of aio which
switched from one thread per process created with lwp_create to a pool
of _kthreads_ created with kthread_create, which have no associated
process:

-       error = lwp_create(curlwp, p, uaddr, 0, NULL, 0, aio_worker,
-           NULL, &l, curlwp->l_class, &curlwp->l_sigmask, &curlwp->l_sigstk);
-       if (error != 0) {
-               uvm_uarea_free(uaddr);
-               aio_exit(p, aio);
...
+       int error = kthread_create(PRI_NONE, KTHREAD_MUSTJOIN | KTHREAD_TS,
+           NULL, aiost_entry, st, &st->lwp, "aio_%d_%ld", p->p_pid,
+           sp->nthreads_total);

Apparently we have no automatic tests of aio on character devices, or
else we would have hit this assertion immediately in testing.