Date: Fri, 17 May 2013 10:31:01 -0700 From: Jeremy Chadwick <jdc@koitsu.org> To: dennis berger <db@bsdsystems.de> Cc: FreeBSD stable <freebsd-stable@freebsd.org>, Steven Hartland <killing@multiplay.co.uk> Subject: Re: still mbuf leak in 9.0 / 9.1? Message-ID: <20130517173101.GB87223@icarus.home.lan> In-Reply-To: <1186B7CE-EC84-42F6-8904-EDD0C4A5FFBD@bsdsystems.de> References: <FDFFFCCB-BDF8-4E27-AF9D-D14D7E0D426D@nipsi.de> <CAFOYbcmF5WybuyJ9DuotcJf_u1FxwBKOLtHvpnT-05cVG6ES=A@mail.gmail.com> <004BC6EA-D8E6-473E-851C-9CDA7578510A@nipsi.de> <20130515211436.GA42790@icarus.home.lan> <696B5622-A95D-4187-A027-07ECC9B5AD1F@nipsi.de> <F3B040438E014E958372DCD64566CED4@multiplay.co.uk> <4F319A22-E611-4EE6-A970-98315B15C12F@nipsi.de> <1186B7CE-EC84-42F6-8904-EDD0C4A5FFBD@bsdsystems.de>
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On Fri, May 17, 2013 at 11:37:23AM +0200, dennis berger wrote:
> Hi List,
> I can confirm that it is the bug you mentioned steven.
> Here is how I found it.
>
> I recorded hourly zfskern and nfsd stats. like this.
>
> echo "PROCSTAT" >> $reportname
> pgrep -S "(zfskern|nfsd)" | xargs procstat -kk >> $reportname
>
> luckily it crashed this night and logged this.
>
> 1910 101508 nfsd nfsd: service mi_switch+0x186 sleepq_wait+0x42 _sleep+0x376 arc_lowmem+0x77 kmem_malloc+0xc1 uma_large_malloc+0x4a malloc+0xd9 arc_get_data_buf+0xb5 arc_read_nolock+0x1ec arc_read+0x93 dbuf_prefetch+0x12c dmu_zfetch_dofetch+0x10b dmu_zfetch+0xaf8 dbuf_read+0x4a7 dmu_buf_hold_array_by_dnode+0x16b dmu_buf_hold_array+0x67 dmu_read_uio+0x3f zfs_freebsd_read+0x3e3
>
> Maybe it would be good to merge this fix into RELENG_9_1 and distribute a fix via freebsd-update what do you think?
>
> best,
> -dennis
>
>
> Am 16.05.2013 um 11:42 schrieb dennis berger:
>
> > This is indeed a ZFS+NFS system and I can see that istgt and nfs are stuck in some ZIO state. Maybe it's this.
> > Thank's for pointing out.
> >
> > Is it this ZFS+NFS deadlock?
> >
> > --- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c
> > +++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c
> > @@ -3720,8 +3720,16 @@ arc_lowmem(void *arg __unused, int howto __unused)
> > mutex_enter(&arc_reclaim_thr_lock);
> > needfree = 1;
> > cv_signal(&arc_reclaim_thr_cv);
> > - while (needfree)
> > - msleep(&needfree, &arc_reclaim_thr_lock, 0, "zfs:lowmem", 0);
> > +
> > + /*
> > + * It is unsafe to block here in arbitrary threads, because we can come
> > + * here from ARC itself and may hold ARC locks and thus risk a deadlock
> > + * with ARC reclaim thread.
> > + */
> > + if (curproc == pageproc) {
> > + while (needfree)
> > + msleep(&needfree, &arc_reclaim_thr_lock, 0, "zfs:lowmem", 0);
> > + }
> > mutex_exit(&arc_reclaim_thr_lock);
> > mutex_exit(&arc_lowmem_lock);
> > }
> >
> > I'll try to crash our testsystem. I'll assume that stressing NFS backed with ZFS a lot might trigger this bug?
> >
> > -dennis
> >
> >
> > Am 16.05.2013 um 00:03 schrieb Steven Hartland:
> >
> >> ----- Original Message ----- From: "dennis berger" <db@nipsi.de>
> >>> FreeBSD 9.1-RELEASE FreeBSD 9.1-RELEASE #0 r243825: Tue Dec 4 09:23:10 UTC 2012
> >>>
> >>>> 3. Regarding this:
> >>>>>> A clean shutdown isn't possible though. It hangs after vnode
> >>>>>> cleaning, normally you would see detaching of usb devices here, or
> >>>>>> other devices maybe?
> >>>> Please don't conflate this with your above issue. This is almost
> >>>> certainly unrelated. Please start a new thread about that if desired.
> >>>
> >>> Maybe this is a misunderstanding normally this system will shutdown cleanly, of course.
> >>> This hang only appears after the network problem above.
> >>
> >> If this is a ZFS system, its a known issue which is fixed in current,
> >> stable-9, stable-8 and the upcoming 8.4 release.
> >>
> >> If not and you have USB devices see if the following sysctl helps:
> >> hw.usb.no_shutdown_wait=1
I'm sorry to say it won't happen. The only updates that the -RELEASE
branches get are for security. If you want fixes for other things, you
need to follow/run stables branches (i.e. stable/9), otherwise you will
need to wait until 9.2-RELEASE comes out.
--
| Jeremy Chadwick jdc@koitsu.org |
| UNIX Systems Administrator http://jdc.koitsu.org/ |
| Mountain View, CA, US |
| Making life hard for others since 1977. PGP 4BD6C0CB |
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