Date: Sat, 18 May 2013 12:14:28 +0200 From: "Ronald Klop" <ronald-freebsd8@klop.yi.org> To: "dennis berger" <db@bsdsystems.de>, "Jeremy Chadwick" <jdc@koitsu.org> Cc: Steven Hartland <killing@multiplay.co.uk>, FreeBSD stable <freebsd-stable@freebsd.org> Subject: Re: still mbuf leak in 9.0 / 9.1? Message-ID: <op.ww9yqee88527sy@ronaldradial> In-Reply-To: <20130517173101.GB87223@icarus.home.lan> 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> <20130517173101.GB87223@icarus.home.lan>
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On Fri, 17 May 2013 19:31:01 +0200, Jeremy Chadwick <jdc@koitsu.org> wrote:
> 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.
>
And errata notices? Are they for security?
Ronald.
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