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Date:      Tue, 7 Mar 2017 00:10:31 -0800
From:      Mark Millard <markmi@dsl-only.net>
To:        Mark Johnston <markj@FreeBSD.org>
Cc:        Justin Hibbits <chmeeedalf@gmail.com>, FreeBSD PowerPC ML <freebsd-ppc@freebsd.org>
Subject:   Re: powerpc64 head -r314687 (PowerMac G5 so-called "Quad Core", clang based): CAM status: Command timeout (always?)
Message-ID:  <49DE6E23-948B-4DC1-87A0-047F8A2CE966@dsl-only.net>
In-Reply-To: <2FA8AC16-8108-4FC7-B1E6-788CBD32F372@dsl-only.net>
References:  <98A62E0D-C2A0-40B1-AE6D-5810906208AE@dsl-only.net> <4C78F6AA-5ABD-4445-B5EF-4E6778CE36FE@dsl-only.net> <20170306164341.GA83069@wkstn-mjohnston.west.isilon.com> <466C25ED-0A70-4988-9BB1-3B43BD031E5E@dsl-only.net> <E67A6606-941D-4F00-993D-4347C2A1D332@dsl-only.net> <20170307010204.GA3611@wkstn-mjohnston.west.isilon.com> <2FA8AC16-8108-4FC7-B1E6-788CBD32F372@dsl-only.net>

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On 2017-Mar-6, at 8:03 PM, Mark Millard <markmi at dsl-only.net> wrote:

> I'm no longer able to reproduce the problem, not even with an
> "svnlite update -r314687" based build where "svnlite status
> /usr/src/" does not list ether of the files. This was after
> trying the patch sequence, which had no failures at any stage.
>=20
> This suggests some sort of intermittent problem someplace.
>=20
> At least it fits with your not finding a way for your code
> update to cause the results that I got.
>=20
> But finding such an intermittent problem is a pain. I've
> no clue if/when I'll even see an example again, much less
> find a way to investigate it if I do. (PowerMac's do not
> take ddb input early.)
>=20
> There is the possibility that the recent atomic_fcmpset based
> locking changes still has some sort of problem, just not seen
> often. Not easy to find if true.
>=20
> Anyway I'm now running -r314687 with:
>=20
> # svnlite status /usr/src/ | sort
> ?       /usr/src/sys/amd64/conf/GENERIC-DBG
> ?       /usr/src/sys/amd64/conf/GENERIC-NODBG
> ?       /usr/src/sys/arm/conf/BPIM3-DBG
> ?       /usr/src/sys/arm/conf/BPIM3-NODBG
> ?       /usr/src/sys/arm/conf/RPI2-DBG
> ?       /usr/src/sys/arm/conf/RPI2-NODBG
> ?       /usr/src/sys/arm64/conf/GENERIC-DBG
> ?       /usr/src/sys/arm64/conf/GENERIC-NODBG
> ?       /usr/src/sys/powerpc/conf/GENERIC64vtsc-DBG
> ?       /usr/src/sys/powerpc/conf/GENERIC64vtsc-NODBG
> ?       /usr/src/sys/powerpc/conf/GENERICvtsc-DBG
> ?       /usr/src/sys/powerpc/conf/GENERICvtsc-NODBG
> M       /usr/src/bin/sh/jobs.c
> M       /usr/src/bin/sh/miscbltin.c
> M       /usr/src/contrib/llvm/tools/lld/ELF/Target.cpp
> M       /usr/src/crypto/openssl/crypto/armcap.c
> M       /usr/src/lib/csu/powerpc64/Makefile
> M       /usr/src/libexec/rtld-elf/Makefile
> M       /usr/src/sys/arm/arm/gic.c
> M       /usr/src/sys/boot/ofw/Makefile.inc
> M       /usr/src/sys/boot/powerpc/Makefile.inc
> M       /usr/src/sys/boot/powerpc/kboot/Makefile
> M       /usr/src/sys/boot/uboot/Makefile.inc
> M       /usr/src/sys/conf/kmod.mk
> M       /usr/src/sys/ddb/db_main.c
> M       /usr/src/sys/ddb/db_script.c
> M       /usr/src/sys/powerpc/ofw/ofw_machdep.c
>=20
> (which are long standing in my environment).
>=20
> I'll build and try a debug kernel but I'm not hopeful
> for it finding anything.

The debug kernel has not failed so far but does report
sleeping with a non-sleepable lock held (in addition
to a lor):

SMP: AP CPU #3 launched
SMP: AP CPU #2 launched
SMP: AP CPU #1 launched
WARNING: WITNESS option enabled, expect reduced performance.
WARNING: DIAGNOSTIC option enabled, expect reduced performance.
Trying to mount root from ufs:/dev/ufs/FBSDG5Lrootfs [rw,noatime]...
ugen0.2: <Mitsumi Electric Hub in Apple Extended USB Keyboard> at usbus0
uhub3 on uhub0
uhub3: <Mitsumi Electric Hub in Apple Extended USB Keyboard, class 9/0, =
rev 1.10/4.20, addr 2> on usbus0
Expensive timeout(9) function: 0xe84630(0xdc4a10) 0.026154120 s
Sleeping on "smu" with the following non-sleepable locks held:
exclusive sleep mutex tod2rl (tod2rl) r =3D 0 (0x122ef50) locked @ =
/usr/src/sys/kern/subr_rtc.c:135
stack backtrace:
#0 0x60e3bc at .get_spr+0x50d4dc
#1 0x59a200 at .get_spr+0x499320
#2 0x91b4cc at .rtascall+0x11dac
#3 0x91a76c at .rtascall+0x1104c
#4 0x5f0680 at .get_spr+0x4ef7a0
#5 0x68729c at .get_spr+0x5863bc
#6 0x512af4 at .get_spr+0x411c14
#7 0x546600 at .get_spr+0x445720
#8 0x935f70 at .fork_trampoline+0x10
#9 0x935e44 at blocked_loop+0x38
lock order reversal: (Giant after non-sleepable)
 1st 0x122ef50 tod2rl (tod2rl) @ /usr/src/sys/kern/subr_rtc.c:135
 2nd 0x1200b00 Giant (Giant) @ /usr/src/sys/kern/kern_synch.c:230
stack backtrace:
#0 0x60c9e4 at .get_spr+0x50bb04
#1 0x56c504 at .get_spr+0x46b624
#2 0x59a5d0 at .get_spr+0x4996f0
#3 0x91b4cc at .rtascall+0x11dac
#4 0x91a76c at .rtascall+0x1104c
#5 0x5f0680 at .get_spr+0x4ef7a0
#6 0x68729c at .get_spr+0x5863bc
#7 0x512af4 at .get_spr+0x411c14
#8 0x546600 at .get_spr+0x445720
#9 0x935f70 at .fork_trampoline+0x10
#10 0x935e44 at blocked_loop+0x38
uhub3: 3 ports with 2 removable, bus powered
Setting hostuuid: 11fe4cb1-3cac-11e4-a5a8-001451685a44.
Setting hostid: 0x489b688f.
Starting file system checks:
/dev/ufs/FBSDG5Lrootfs: FILE SYSTEM CLEAN; SKIPPING CHECKS
/dev/ufs/FBSDG5Lrootfs: clean, 82126801 free (1058921 frags, 10133485 =
blocks, 1.1% fragmentation)
Mounting local filesystems:.

(The symbolic routine names it shows are not of much use.
I could use /usr/local/bin/objdump to look things up.)

Later there is another lor:

No core dumps found.
Clearing /tmp (X related).
NFSv4 is disabled
lock order reversal:
 1st 0xa046b78 ufs (ufs) @ /usr/src/sys/kern/vfs_subr.c:2600
 2nd 0xc0000000b6c90ba0 bufwait (bufwait) @ =
/usr/src/sys/ufs/ffs/ffs_vnops.c:280
 3rd 0xb22e5f0 ufs (ufs) @ /usr/src/sys/kern/vfs_subr.c:2600
stack backtrace:
#0 0x60c9e4 at .get_spr+0x50bb04
#1 0x55fc9c at .get_spr+0x45edbc
#2 0x88649c at .get_spr+0x7855bc
#3 0x945a34 at .phyp_pft_hcall+0xd1e4
#4 0x6a2288 at .get_spr+0x5a13a8
#5 0x68d4e4 at .get_spr+0x58c604
#6 0x67bd3c at .get_spr+0x57ae5c
#7 0x88172c at .get_spr+0x78084c
#8 0x876518 at .get_spr+0x775638
#9 0x8873e8 at .get_spr+0x786508
#10 0x859098 at .get_spr+0x7581b8
#11 0x88fc94 at .get_spr+0x78edb4
#12 0x89a920 at .get_spr+0x799a40
#13 0x895da0 at .get_spr+0x794ec0
#14 0x941370 at .phyp_pft_hcall+0x8b20
#15 0x6a19a8 at .get_spr+0x5a0ac8
#16 0x6a1630 at .get_spr+0x5a0750
#17 0x698290 at .get_spr+0x5973b0
Starting mountd.

The rest looks normal.

=3D=3D=3D
Mark Millard
markmi at dsl-only.net




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