Date: Tue, 3 May 2011 23:58:49 -0700 From: Garrett Cooper <yanegomi@gmail.com> To: Kirk McKusick <mckusick@mckusick.com> Cc: FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: Nasty non-recursive lockmgr panic on softdep only enabled UFS partition when filesystem full Message-ID: <BANLkTik8F_SvEzW-vPW9=dZUEJuYOy9WcQ@mail.gmail.com> In-Reply-To: <BANLkTikAQ6Jz4Jbjxh51iA-cjCYmdx1mSg@mail.gmail.com> References: <BANLkTik4=O_1PWB2GzGzY=m51dG-Kbhe%2BQ@mail.gmail.com> <201105040559.p445xEJ5024585@chez.mckusick.com> <BANLkTikAQ6Jz4Jbjxh51iA-cjCYmdx1mSg@mail.gmail.com>
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On Tue, May 3, 2011 at 11:42 PM, Garrett Cooper <yanegomi@gmail.com> wrote:
> On Tue, May 3, 2011 at 10:59 PM, Kirk McKusick <mckusick@mckusick.com> wr=
ote:
>>> Date: Tue, 3 May 2011 22:40:26 -0700
>>> Subject: Nasty non-recursive lockmgr panic on softdep only enabled UFS
>>> =A0partition when filesystem full
>>> From: Garrett Cooper <yanegomi@gmail.com>
>>> To: Jeff Roberson <jeff@freebsd.org>,
>>> =A0 =A0 =A0 =A0 Marshall Kirk McKusick <mckusick@mckusick.com>
>>> Cc: FreeBSD Current <freebsd-current@freebsd.org>
>>>
>>> Hi Jeff and Dr. McKusick,
>>> =A0 =A0 Ran into this panic when /usr ran out of space doing a make
>>> universe on amd64/r221219 (it took ~15 minutes for the panic to occur
>>> after the filesystem ran out of space -- wasn't quite sure what it was
>>> doing at the time):
>>>
>>> ...
>>>
>>> =A0 =A0 Let me know what other commands you would like for me to run in=
kgdb.
>>> Thanks,
>>> -Garrett
>>
>> You did not indicate whether you are running an 8.X system or a 9-curren=
t
>> system. It would be helpful to know that.
>
> I've actually been running CURRENT for a few years now, but you're right =
--
> I didn't mention that part.
>
>> Jeff thinks that there may be a potential race in the locking code for
>> softdep_request_cleanup. If so, this patch for 9-current should fix it:
>>
>> Index: ffs_softdep.c
>> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>> --- ffs_softdep.c =A0 =A0 =A0 (revision 221385)
>> +++ ffs_softdep.c =A0 =A0 =A0 (working copy)
>> @@ -11380,7 +11380,8 @@
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0continue;
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0}
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0MNT_IUNLOCK(mp);
>> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (vget(lvp, LK_EXCLUSIVE=
| LK_INTERLOCK, curthread)) {
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (vget(lvp, LK_EXCLUSIVE=
| LK_NOWAIT | LK_INTERLOCK,
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 curthread)) {
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0MNT_ILOCK=
(mp);
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0continue;
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0}
>>
>> If you are running an 8.X system, hopefully you will be able to apply it=
.
>
> =A0 =A0I've applied it, rebuilt and installed the kernel, and trying to
> repro the case again. Will let you know how things go!
Happened again with the change. It's really easy to repro:
1. Get a filesystem with UFS+SU
2. Execute something that does a large number of small writes to a partitio=
n.
3. 'dd if=3D/dev/zero of=3DFOO bs=3D10m' on the same partition
The kernel will panic with the issue I discussed above.
Thanks!
-Garrett
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