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Date:      Sat, 17 Feb 2018 18:10:16 -0800
From:      Mark Millard <marklmi26-fbsd@yahoo.com>
To:        FreeBSD Current <freebsd-current@freebsd.org>, FreeBSD Hackers <freebsd-hackers@freebsd.org>
Subject:   Re: amd64 head -r329465 (non-debug build, but with symbols): "panic: spin lock held too long" during make check-old, reported during a sys_vfork
Message-ID:  <6907E068-C80A-44B8-A8AD-3EF27D52D127@yahoo.com>
In-Reply-To: <DA76F62D-3373-47CA-AD95-DE9BA580772B@yahoo.com>
References:  <DA76F62D-3373-47CA-AD95-DE9BA580772B@yahoo.com>

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[Some more information added, from /usr/libexec/kgdb use.]

On 2018-Feb-17, at 5:39 PM, Mark Millard <marklmi26-fbsd at yahoo.com> =
wrote:

> This is for FreeBSD running under Hyper-V on a Windows 10 Pro machine.
> The FreeBSD "disk" bindings are to SSDs, not the insides of NTFS =
files.
> 29 logical processors assigned to FreeBSD (on a 32-thread Ryzen
> Threadripper 1950X). No other Hyper-V use.
>=20
> This happened during:
>=20
> # =
~/sys_build_scripts.amd64-host/make_powerpc64vtsc_nodebug_clang_altbinutil=
s-amd64-host.sh check-old =
DESTDIR=3D/usr/obj/DESTDIRs/clang-powerpc64-installworld_altbinutils
> Script started, output file is =
/root/sys_typescripts/typescript_make_powerpc64vtsc_nodebug_clang_altbinut=
ils-amd64-host-2018-02-17:15:56:20
>>>> Checking for old files
>=20
>=20
> (Hand typed from a picture of a window's content
> at slighly different times, expect typos:)
>=20
> KDB: enter: panic
> [thread pid 42170 tid 100752 ]
> Stopped at kdb_enter+0x3b: movq $0,kdb_why
> db> call doadump
> Dumping 4825 out of 110559 MB: ... (omitted) ...
> Dump complete
> =3D 0
>=20
>=20
> (The "pid 42170" identification as the process reporting the
> issue does not seem to appear in the core.txt.0 file.)
>=20
>=20
> # ls -lTdt /var/crash/*
> -rw-r--r--  1 root  wheel      100792 Feb 17 16:09:18 2018 =
/var/crash/core.txt.0
> lrwxr-xr-x  1 root  wheel           8 Feb 17 16:09:08 2018 =
/var/crash/vmcore.last -> vmcore.0
> lrwxr-xr-x  1 root  wheel           6 Feb 17 16:09:08 2018 =
/var/crash/info.last -> info.0
> -rw-------  1 root  wheel  5060296704 Feb 17 16:09:08 2018 =
/var/crash/vmcore.0
> -rw-------  1 root  wheel         392 Feb 17 16:08:59 2018 =
/var/crash/info.0
> -rw-r--r--  1 root  wheel           2 Feb 17 16:08:59 2018 =
/var/crash/bounds
> -rw-r--r--  1 root  wheel           5 Nov 22 04:34:36 2017 =
/var/crash/minfree
>=20
> =46rom /var/crash/core.txt.0 :
>=20
> Unread portion of the kernel message buffer:
> spin lock 0xffffffff81b2dcc0 (sched lock 5) held by 0xfffff8011d936560 =
(tid 100691) too long
> panic: spin lock held too long
> cpuid =3D 5
> time =3D 1518911834
> KDB: stack backtrace:
> db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame =
0xfffffe00f10094d0
> vpanic() at vpanic+0x18d/frame 0xfffffe00f1009530
> panic() at panic+0x43/frame 0xfffffe00f1009590
> _mtx_lock_indefinite_check() at _mtx_lock_indefinite_check+0x71/frame =
0xfffffe00f10095a0
> thread_lock_flags_() at thread_lock_flags_+0xdb/frame =
0xfffffe00f1009610
> statclock_cnt() at statclock_cnt+0xdc/frame 0xfffffe00f1009650
> handleevents() at handleevents+0x113/frame 0xfffffe00f10096a0
> timercb() at timercb+0xa9/frame 0xfffffe00f10096f0
> lapic_handle_timer() at lapic_handle_timer+0xa7/frame =
0xfffffe00f1009730
> timerint_u() at timerint_u+0x96/frame 0xfffffe00f1009810
> thread_lock_flags_() at thread_lock_flags_+0xc1/frame =
0xfffffe00f1009880
> fork1() at fork1+0x1b9f/frame 0xfffffe00f1009930
> sys_vfork() at sys_vfork+0x4c/frame 0xfffffe00f1009980
> amd64_syscall() at amd64_syscall+0xa48/frame 0xfffffe00f1009ab0
> fast_syscall_common() at fast_syscall_common+0x101/frame =
0x7fffffffcfc0
> KDB: enter: panic
>=20
> __curthread () at ./machine/pcpu.h:230
> 230             __asm("movq %%gs:%1,%0" : "=3Dr" (td)
> (kgdb) #0  __curthread () at ./machine/pcpu.h:230
> #1  doadump (textdump=3D-2122191464) at =
/usr/src/sys/kern/kern_shutdown.c:347
> #2  0xffffffff8040b42c in db_fncall_generic (addr=3D<optimized out>,=20=

>   rv=3D<optimized out>, nargs=3D<optimized out>, args=3D<optimized =
out>)
>   at /usr/src/sys/ddb/db_command.c:609
> #3  db_fncall (dummy1=3D<optimized out>, dummy2=3D<optimized out>,=20
>   dummy3=3D<optimized out>, dummy4=3D<optimized out>)
>   at /usr/src/sys/ddb/db_command.c:657
> #4  0xffffffff8040af79 in db_command (last_cmdp=3D<optimized out>,=20
>   cmd_table=3D<optimized out>, dopager=3D<optimized out>)
>   at /usr/src/sys/ddb/db_command.c:481
> #5  0xffffffff8040acf4 in db_command_loop ()
>   at /usr/src/sys/ddb/db_command.c:534
> #6  0xffffffff8040df9f in db_trap (type=3D<optimized out>, =
code=3D<optimized out>)
>   at /usr/src/sys/ddb/db_main.c:250
> #7  0xffffffff80b370e3 in kdb_trap (type=3D3, code=3D-61456, =
tf=3D<optimized out>)
>   at /usr/src/sys/kern/subr_kdb.c:697
> #8  0xffffffff80fa2c5c in trap (frame=3D0xfffffe00f1009400)
>   at /usr/src/sys/amd64/amd64/trap.c:547
> #9  <signal handler called>
> #10 kdb_enter (why=3D0xffffffff811f280b "panic", msg=3D<optimized =
out>)
>   at /usr/src/sys/kern/subr_kdb.c:479
> #11 0xffffffff80aef17a in vpanic (fmt=3D<optimized out>, =
ap=3D0xfffffe00f1009570)
>   at /usr/src/sys/kern/kern_shutdown.c:801
> #12 0xffffffff80aeefc3 in panic (fmt=3D0x0)
>   at /usr/src/sys/kern/kern_shutdown.c:739
> #13 0xffffffff80acfa31 in _mtx_lock_indefinite_check (m=3D<optimized =
out>,=20
>   ldap=3D<optimized out>) at /usr/src/sys/kern/kern_mutex.c:1224
> #14 0xffffffff80acfb9b in thread_lock_flags_ (td=3D0xfffff818719d1000,=20=

>   opts=3D<optimized out>, file=3D<optimized out>, line=3D<optimized =
out>)
>   at /usr/src/sys/kern/kern_mutex.c:913
> #15 0xffffffff80a89d6c in statclock_cnt (cnt=3D1, usermode=3D<optimized =
out>)
>   at /usr/src/sys/kern/kern_clock.c:768
> #16 0xffffffff810d0003 in handleevents (now=3D43230207690178, fake=3D0)
>   at /usr/src/sys/kern/kern_clocksource.c:196
> #17 0xffffffff810d0709 in timercb (et=3D0xffffffff81c528e8 <lapic_et>,=20=

>   arg=3D<optimized out>) at /usr/src/sys/kern/kern_clocksource.c:353
> #18 0xffffffff8110dad7 in lapic_handle_timer =
(frame=3D0xfffffe00f1009740)
>   at /usr/src/sys/x86/x86/local_apic.c:1305
> #19 0xffffffff80f849d0 in timerint_u ()
>   at /usr/src/sys/amd64/amd64/apic_vector.S:132
> #20 0xfffffe00f1009828 in ?? ()
> #21 0x000000000000b6b1 in ?? ()
> #22 0x0000000000002000 in ?? ()
> #23 0x00000000ffffdfff in ?? ()
> #24 0x00c11c08e43e7fd5 in ?? ()
> #25 0x00000000000003e8 in ?? ()
> #26 0x00000000fffff1eb in ?? ()
> #27 0xfffffe00f1009828 in ?? ()
> #28 0xfffffe00f1009810 in ?? ()
> #29 0x00000000800e6d01 in ?? ()
> #30 0x0000000000000064 in ?? ()
> #31 0xfffff8011d936560 in ?? ()
> #32 0xfffffe00f1009828 in ?? ()
> #33 0xffffffff81771014 in mtx_delay ()
> #34 0x0000000000000000 in ?? ()
> (kgdb)=20
>=20
> . . .
> UID   PID  PPID CPU PRI NI   VSZ   RSS MWCHAN   STAT TT     TIME =
COMMAND
> . . .
>  0  1110  1102   0  33  0 12024  3076 ttyin    D+    -  0:00.00 [sh]
>  0  1120  1044   0  20  0 18572  7936 select   Ds    -  0:00.00 [sshd]
> 1001  1123  1120   0  20  0 18936  8044 select   D     -  0:00.00 =
[sshd]
> 1001  1124  1123   0  34  0 12120  3196 wait     Ds    -  0:00.00 [sh]
>  0  1134  1124   0  22  0 12060  3148 wait     D     -  0:00.00 [su]
>  0  1135  1134   0  20  0 12312  3244 wait     D     -  0:00.00 [sh]
>  0 42072  1135   0  25  0 11464  3060 wait     D+    -  0:00.00 [sh]
>  0 42072  1135   0  25  0 11464  3060 wait     D+    -  0:00.00 [sh]
>  0 42075 42072   0  20  0 10928  2480 select   D+    -  0:00.00 =
[script]
>  0 42076 42075   0  52  0 10160  1396 wait     Ds+   -  0:00.00 [make]
>  0 42108 42076   0  52  0 12236  3224 wait     D+    -  0:00.00 [make]
>  0 42168 42108   0  52  0 11496  3068 wait     D+    -  0:00.00 [sh]
>  0 42169 42168   0  52  0 12608  3568 pipewr   D+    -  0:00.00 [make]
>  0 42170 42168   0  72  0 10956  2284 -        R+    -  0:00.00 =
[xargs]
>  0 42171 42168   0  35  0 11500  3064 piperd   D+    -  0:00.00 [sh]
>  0 46769 42170   0  72  0 10956  2284 -        ?VL+  -  0:00.00 =
[xargs]
> . . .
>=20
>=20
>=20
>=20
> Context details:
>=20
> # uname -apKU
> FreeBSD FBSDFSSD 12.0-CURRENT FreeBSD 12.0-CURRENT  r329465M  amd64 =
amd64 1200058 1200058
>=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/GENERIC-DBG
> ?       /usr/src/sys/arm/conf/GENERIC-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/contrib/llvm/lib/Target/PowerPC/PPCFrameLowering.cpp
> M       /usr/src/contrib/llvm/tools/lld/ELF/Arch/PPC64.cpp
> M       /usr/src/crypto/openssl/crypto/armcap.c
> M       /usr/src/lib/libkvm/kvm_powerpc.c
> M       /usr/src/lib/libkvm/kvm_private.c
> M       /usr/src/stand/defs.mk
> M       /usr/src/stand/powerpc/boot1.chrp/Makefile
> M       /usr/src/stand/powerpc/kboot/Makefile
> M       /usr/src/sys/arm64/arm64/identcpu.c
> M       /usr/src/sys/conf/kmod.mk
> M       /usr/src/sys/conf/ldscript.powerpc
> M       /usr/src/sys/kern/subr_pcpu.c
> M       /usr/src/sys/powerpc/aim/mmu_oea64.c
> M       /usr/src/sys/powerpc/ofw/ofw_machdep.c
> M       /usr/src/sys/powerpc/powerpc/interrupt.c
> M       /usr/src/sys/powerpc/powerpc/mp_machdep.c
> M       /usr/src/sys/powerpc/powerpc/trap.c
> M       /usr/src/sys/vm/uma_core.c
> M       /usr/src/usr.bin/top/machine.c
>=20
> The GENERIC* files include GENERIC and then set explicit
> debug status choices of mine. Most of the rest is tied to
> historical powerpc and powerpc64 investigations. I also
> have top report the maximum swap-in-use figure that it
> sees during its run.
>=20
> # svnlite diff /usr/src/sys/vm/uma_core.c
> Index: /usr/src/sys/vm/uma_core.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
> --- /usr/src/sys/vm/uma_core.c	(revision 329465)
> +++ /usr/src/sys/vm/uma_core.c	(working copy)
> @@ -3428,7 +3428,7 @@
> void
> uma_reclaim_wakeup(void)
> {
> -
> +printf("limit %lX, total %lX, needed %d\n", uma_kmem_limit, =
uma_kmem_total, uma_reclaim_needed);
> 	if (atomic_fetchadd_int(&uma_reclaim_needed, 1) =3D=3D 0)
> 		wakeup(uma_reclaim);
> }
>=20
>=20
>=20
> Side note: It took the automatic fsck and 2 manual fsck
> runs to get back to a clean status (before I could get to
> multi-user).

/usr/local/bin/kgdb did not seem to work. But
/usr/libexec/kgdb seems to. (This is likely the first time
that I've used a normal vmcore.* file on any architecture.
On powerpc I had to hack things into a non-default way of
working. On powerpc64 dumps used to fail.)

# /usr/libexec/kgdb /usr/lib/debug/boot/kernel/kernel.debug =
/var/crash/vmcore.0
GNU gdb 6.1.1 [FreeBSD]
. . .

So here is what thread 100691 gets as a report in
"info threads" --100752 shows "doadump", but of course
was doing a fork at the time of the problem:

(kgdb) info threads
  558 Thread 100691 (PID=3D46769: xargs)  fork_trampoline () at =
/usr/src/sys/amd64/amd64/exception.S:840
. . .
* 556 Thread 100752 (PID=3D42170: xargs)  doadump (textdump=3D0x8181ed98) =
at pcpu.h:230
. . .

The bt for 558 (a.k.a. 100691) does not seem to have much
information:

(kgdb) thread 558
[Switching to thread 558 (Thread 100691)]#0  fork_trampoline () at =
/usr/src/sys/amd64/amd64/exception.S:840
840		movq	%r12,%rdi		/* function */
Current language:  auto; currently asm
(kgdb) bt
#0  fork_trampoline () at /usr/src/sys/amd64/amd64/exception.S:840
#1  0xffffffff80f8398d in fast_syscall_common () at =
/usr/src/sys/amd64/amd64/exception.S:480
#2  0x0000000800c43000 in ?? ()
#3  0x0000000000203353 in ?? ()
#4  0x0000000000000001 in .rodata ()
#5  0x0000000800c43008 in ?? ()
#6  0x00c11c08e43e7fd5 in ?? ()
#7  0x0000000000000000 in ?? ()
(kgdb)=20

But the kernel message buffer material reported:
(repeated from the earlier Email)

spin lock 0xffffffff81b2dcc0 (sched lock 5) held by 0xfffff8011d936560 =
(tid 100691) too long


I'll note that I have no known way to cause a repeat. I'd been doing the =
same sort of
build activity for a time when this happened.

=3D=3D=3D
Mark Millard
marklmi at yahoo.com
( markmi at dsl-only.net is
going away in 2018-Feb, late)




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