Date: Thu, 9 Apr 2020 14:02:51 -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%2Bb0zg9DZys8v--Rwtg1qBkz8XbByehq6vr-xmLtjenNGgRKiQ@mail.gmail.com> In-Reply-To: <20200407232347.GA5605@raichu> 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>
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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
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