Re: 3.2-rc4: scrubbing locks up the kernel, then hung tasks on boot

[Martin Steigerwald <ms@teamix.de>]

Am Sonntag, 18. M=C3=A4rz 2012 schrieb Greg Kroah-Hartman:
> On Sat, Mar 17, 2012 at 10:43:25AM +0100, Martin Steigerwald wrote:
> > Hi Greg, Chris, Arne, hi everyone,
> >=20
> > Am Freitag, 16. M=C3=A4rz 2012 schrieb Martin Steigerwald:
> > > Am Donnerstag, 15. M=C3=A4rz 2012 schrieb Chris Mason:
> > > > On Thu, Mar 15, 2012 at 06:32:19PM +0100, Martin Steigerwald wr=
ote:
> > > > > Am Samstag, 25. Februar 2012 schrieb Arne Jansen:
> > > > > > On 02/24/12 16:51, Martin Steigerwald wrote:
> > > > > > > Am Samstag, 21. Januar 2012 schrieb Martin Steigerwald:
> > > > > > >> Am Samstag, 21. Januar 2012 schrieb Martin Steigerwald:
> > > > > > >>> I still have this with 3.2.0-1-pae - which is a debian =
kernel
> > > > > > >>> based on 3.2.1.
> > > > > > >>>=20
> > > > > > >>> When I do btrfs scrub start / the machine locks immedia=
tely
> > > > > > >>> up hard.
> > > > > > >>>=20
> > > > > > >>> Then usually on next boot it stops on space_cache enabl=
ed
> > > > > > >>> message, but not  the one for /, but the one for /home =
which
> > > > > > >>> is mounted later.
> > >=20
> > > [=E2=80=A6]
> > >=20
> > > > > > >> I now tested scrubbing /home which is a different BTRFS
> > > > > > >> filesystem on the same machine.
> > > > > > >>=20
> > > > > > >> Then the scrub is started, scrub status tells me so, but
> > > > > > >> nothing happens, no block in/out activity in vmstat, no =
CPU
> > > > > > >> related activity in top.
> > > > > > >>=20
> > > > > > >> btrfs scrub cancel then hangs, but not the complete mach=
ine,
> > > > > > >> only the process.
> > > > > > >>=20
> > > > > > >> I had this once on my T520 with the internal Intel SSD 3=
20 as
> > > > > > >> well. The other time it worked.
> > > > > > >>=20
> > > > > > >> Well maybe that is due to BTRFS doing something else on =
my T23
> > > > > > >> now:
> > > > > > >>=20
> > > > > > >> deepdance:~>  ps aux | grep ino-cache | grep -v grep
> > > > > > >> root      1992  5.5  0.0      0     0 ?        D    12:1=
5
> > > > > > >> 0:09 [btrfs- ino-cache]
> > >=20
> > > [=E2=80=A6]
> > >=20
> > > > > > >> At least it doesn=C2=B4t lock up hard, so there might re=
ally be
> > > > > > >> something strange with /.
> > > > > > >=20
> > > > > > > FWIW a btrfs filesystem balance / does work. After this a=
 btrfs
> > > > > > > scrub start / still locks the kernel.
> > > > > >=20
> > > > > > Hi Martin,
> > > > > >=20
> > > > > > I just sent 2 patches to the list. Could you please test if=
 these
> > > > > > fix your problem with scrub?
> > > > >=20
> > > > > I didn=C2=B4t yet test it but I tried the first balance then =
scrub stuff
> > > >=20
> > > > > again:
> > > > Looks like you're on a 32 bit machine.  The current for-linus b=
ranch
> > > > has an important fix for scrub on 32 bit that should solve this=
=2E
> > >=20
> > > So finally - the machine did make-kpkg over night and complained =
about
> > > missing Documentation lguest, then I switched off lots from distr=
o
> > > default config and just did the usual make stuff - I was able to =
scrub
> > > both partitions on that ThinkPad T23:
> > >=20
> > > deepdance:~> btrfs scrub status /
> > > scrub status for 2bf5b1dc-1d89-4f0d-a561-1a5551a27275
> > >=20
> > >         scrub started at Fri Mar 16 11:56:12 2012 and finished af=
ter
> > >=20
> > > 741 seconds total bytes scrubbed: 9.62GB with 0 errors
> > >=20
> > > deepdance:~> btrfs scrub status /home
> > > scrub status for a600de65-e1ab-4cbf-b150-bbaeaf9fa98d
> > >=20
> > >         scrub started at Fri Mar 16 12:00:31 2012 and finished af=
ter
> > >=20
> > > 1708 seconds total bytes scrubbed: 36.63GB with 0 errors
> > >=20
> > > Thanks a lot for fixing this.
> > >=20
> > > Tested-by: Martin Steigerwald <martin@lichtvoll.de>
> >=20
> > [=E2=80=A6]
> >=20
> > Would that patch
> >=20
> > Btrfs: fix casting error in scrub reada code
> >=20
> > http://git.kernel.org/?p=3Dlinux/kernel/git/mason/linux-
> > btrfs.git;a=3Dcommit;h=3Da175423c831ea582c06784d1e172d2ce1d79923a
> >=20
> > (sorry for line break. KMail insists on it even when I disable line
> > breaks due to the minus sign in the URL.)
> >=20
> > that I tested above be something for stable?
>=20
> <formletter>
>=20
> This is not the correct way to submit patches for inclusion in the
> stable kernel tree.  Please read Documentation/stable_kernel_rules.tx=
t
> for how to do this properly.
>=20
> </formletter>

What point of the rules do you refer to? Is it

 - It or an equivalent fix must already exist in Linus' tree (upstream)=
=2E

?

Or do you want the patch quoted in the mail?

Anyways its not yet in linus tree AFAIR and from my side it was a quest=
ion=20
whether it should be included at all. I thought it might be good ccing =
you on=20
that question already.

Chris, how about this patch for stable once it hits Linus' tree?

Thanks,
--=20
Martin Steigerwald - teamix GmbH - http://www.teamix.de
gpg: 19E3 8D42 896F D004 08AC A0CA 1E10 C593 0399 AE90
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