Date: Thu, 9 Apr 2020 14:29:45 -0700 From: Eric Joyner <erj@freebsd.org> To: Mark Johnston <markj@freebsd.org> Cc: Hans Petter Selasky <hps@selasky.org>, freebsd-net@freebsd.org, shurd <shurd@freebsd.org>, John Baldwin <jhb@freebsd.org>, Drew Gallatin <gallatin@netflix.com> Subject: Re: Issue with epoch_drain_callbacks and unloading iavf(4) [using iflib] Message-ID: <CA%2Bb0zg-swzucfwLZ4kmBKeE-g44L0EqRnft4wR8-_BataDgR%2Bg@mail.gmail.com> In-Reply-To: <CA%2Bb0zg9DZys8v--Rwtg1qBkz8XbByehq6vr-xmLtjenNGgRKiQ@mail.gmail.com> References: <CA%2Bb0zg809EGMS1Ngr38BSb1yNpDqxbCnAv9eC%2BcDwbMQ5t%2BqXQ@mail.gmail.com> <20200212222219.GE83892@raichu> <CAKdFRZjdiz_axuweksNUHis7jPKXHqOmhQg%2BQWzpVnsKY%2Bcrmg@mail.gmail.com> <20200328225150.GA82767@raichu> <CAKdFRZgm43LmjJ9dYDBGM8EV0ePRMLPr4YW_tPELANXQGpqpCA@mail.gmail.com> <CA%2Bb0zg_k=8nMhapa=T=yTcSJcUrrnG=AfQB%2Be0gPcCrgkbWtCQ@mail.gmail.com> <20200331192024.GE97238@raichu> <CA%2Bb0zg9z7srroWLtV_poedghXjCr0GvHv95cu4JzFrRdZoaeWw@mail.gmail.com> <20200406212903.GA55712@raichu> <CA%2Bb0zg-JM1rjO_OPh16sgM3Hm2hbzePNaW5bcxiL9aOpJ_vsOA@mail.gmail.com> <20200407232347.GA5605@raichu> <CA%2Bb0zg9DZys8v--Rwtg1qBkz8XbByehq6vr-xmLtjenNGgRKiQ@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Thu, Apr 9, 2020 at 2:02 PM Eric Joyner <erj@freebsd.org> wrote: > On Tue, Apr 7, 2020 at 4:24 PM Mark Johnston <markj@freebsd.org> wrote: > >> On Mon, Apr 06, 2020 at 02:34:50PM -0700, Eric Joyner wrote: >> > On Mon, Apr 6, 2020 at 2:29 PM Mark Johnston <markj@freebsd.org> wrote: >> > >> > > On Mon, Apr 06, 2020 at 02:19:25PM -0700, Eric Joyner wrote: >> > > > Mark, >> > > > >> > > > I think I was mistaken about the backtrace looking the same. I was >> > > looking >> > > > at it from within ddb, and I think I focused on the >> > > > epoch_block_handler_preempt line and didn't notice that it only >> stopped >> > > > there this time. Here's the new one I've got from kgdb: >> > > >> > > Thanks. Could you try to print "td->td_name" from frame 4? It should >> > > also be available as er->er_blockedtd. Basically, I'm trying to >> verify >> > > that the interrupt thread itself isn't the one that we're waiting for, >> > > else there is another bug to be fixed. >> > > >> > > If you can provide kernel symbols and vmcore, I'd be happy to look at >> it >> > > myself. >> > > _______________________________________________ >> > > freebsd-net@freebsd.org mailing list >> > > https://lists.freebsd.org/mailman/listinfo/freebsd-net >> > > To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org >> " >> > > >> > >> > Here's what I get: >> > >> > (kgdb) frame 4 >> > #4 epoch_block_handler_preempt (global=0xfffff80003de0100, >> > cr=0xfffffe00dee85900, arg=0x0) at /usr/src/sys/kern/subr_epoch.c:507 >> > 507 } >> > (kgdb) print td->td_name >> > $1 = "if_io_tqg_31\000\000\000\000\000\000\000" >> > (kgdb) print er->er_blockedtd >> > $2 = (struct thread *) 0x0 >> >> I spent some time looking at the core. It looks like we have yet >> another problem: the gtaskqueue code won't exit the net epoch if it is >> constantly running a net task. Could you please retry with the patches >> from before, and this one included? >> >> diff --git a/sys/kern/subr_gtaskqueue.c b/sys/kern/subr_gtaskqueue.c >> index f52f32204644..2b1386a612ee 100644 >> --- a/sys/kern/subr_gtaskqueue.c >> +++ b/sys/kern/subr_gtaskqueue.c >> @@ -345,7 +345,7 @@ gtaskqueue_run_locked(struct gtaskqueue *queue) >> struct epoch_tracker et; >> struct gtaskqueue_busy tb; >> struct gtask *gtask; >> - bool in_net_epoch; >> + bool in net_epoch; >> >> KASSERT(queue != NULL, ("tq is NULL")); >> TQ_ASSERT_LOCKED(queue); >> @@ -361,20 +361,19 @@ gtaskqueue_run_locked(struct gtaskqueue *queue) >> TQ_UNLOCK(queue); >> >> KASSERT(gtask->ta_func != NULL, ("task->ta_func is >> NULL")); >> - if (!in_net_epoch && TASK_IS_NET(gtask)) { >> - in_net_epoch = true; >> + if (TASK_IS_NET(gtask)) { >> NET_EPOCH_ENTER(et); >> - } else if (in_net_epoch && !TASK_IS_NET(gtask)) { >> + in_net_epoch = true; >> + } >> + gtask->ta_func(gtask->ta_context); >> + if (in_net_epoch) { >> NET_EPOCH_EXIT(et); >> in_net_epoch = false; >> } >> - gtask->ta_func(gtask->ta_context); >> >> TQ_LOCK(queue); >> wakeup(gtask); >> } >> - if (in_net_epoch) >> - NET_EPOCH_EXIT(et); >> LIST_REMOVE(&tb, tb_link); >> } >> >> _______________________________________________ >> freebsd-net@freebsd.org mailing list >> https://lists.freebsd.org/mailman/listinfo/freebsd-net >> To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org" >> > > Yeah, I'll give it a spin and try to get back to you before the end of the > week. > > - Eric > I was able to try it out just now, and it looks this (and all of the other patches) finally causes the problem to not appear! I can unload the driver while iavf1 is receiving heavy traffic! - Eric
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?CA%2Bb0zg-swzucfwLZ4kmBKeE-g44L0EqRnft4wR8-_BataDgR%2Bg>