On 10/5/16, Julian Elischer <jul...@freebsd.org> wrote: > In 11 and 12 the taskqueue code has been rewritten in this area but > under 10 this bug still occurs. > > On our appliances this bug stops the system from mounting the ZFS > root, so it is quite severe. > Basically while the thread is sleeping during the ZFS mount of root > (in the while loop), another thread can free the 'task' item it is > checking in that while loop and it can be reused or filled with > 'deadcode' etc., with the waiting code unaware of the change.. The fix > is to refetch the item at the end of the queue each time around the loop. > I don't really want to do the bigger change of MFCing the change in > 11, as it is more extensive, though if someone else does, that's ok by > me. (If it's ABI compatible) > > Any comments or suggestions?
Yes, please commit them. This patch fixes the ZFS + GELI + INVARIANTS problem for us. There is the FreeBSD PR about the issue: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=209580 > > here's the fix in diff form: > > > [robot@porridge /usr/src]$ p4 diff -du ... > --- //depot/pbranches/jelischer/FreeBSD-PZ/10.3/sys/kern/subr_taskqueue.c > 2016-09-27 09:14:59.000000000 -0700 > +++ /usr/src/sys/kern/subr_taskqueue.c 2016-09-27 09:14:59.000000000 -0700 > @@ -441,9 +441,10 @@ > > TQ_LOCK(queue); > task = STAILQ_LAST(&queue->tq_queue, task, ta_link); > - if (task != NULL) > - while (task->ta_pending != 0) > - TQ_SLEEP(queue, task, &queue->tq_mutex, PWAIT, "-", > 0); > + while (task != NULL && task->ta_pending != 0) { > + TQ_SLEEP(queue, task, &queue->tq_mutex, PWAIT, "-", 0); > + task = STAILQ_LAST(&queue->tq_queue, task, ta_link); > + } > taskqueue_drain_running(queue); > KASSERT(STAILQ_EMPTY(&queue->tq_queue), > ("taskqueue queue is not empty after draining")); > > _______________________________________________ > freebsd-hack...@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-hackers > To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org" > _______________________________________________ freebsd-stable@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscr...@freebsd.org"
