>Number: 172166
>Category: kern
>Synopsis: Deadlock in the networking code, possible due to a bug in the
>SCHED_ULE
>Confidential: no
>Severity: serious
>Priority: high
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Sat Sep 29 17:30:01 UTC 2012
>Closed-Date:
>Last-Modified:
>Originator: Eugene Grosbein
>Release: FreeBSD 8.3-STABLE amd64
>Organization:
RDTC JSC
>Environment:
System: FreeBSD 8.3-STABLE/amd64, six-core Intel X5675 CPU (hyperthreading
disabled).
>Description:
I run pretty busy FreeBSD 8.3-STABLE/amd64 based mpd-5.6 PPPoE server
that serves hundreds (and sometimes over a thousand) simultaneous
connections
with high connect/disconnect rate. Also, it sends its logs
to remote syslog collector over the net. It also heavily uses
ipfw tables for dummynet shaping: every new connected client
obtains its IP and this IP is added by mpd to some of ipfw tables.
Upon disconnection, mpd removes that IP from tables.
Today, my server deadlocked second time in two months:
all of its network activity got blocked, even lagg's LACP frames.
The kernel and userland were fine, I managed to login using IP KVM
console.
I have invoked KDB, did 'call doadump', obtained crashdump and rebooted
the box.
I've digged it a little; it seems syslogd(8) was preempted by the
scheduler
in the middle of ipfw_lookup_table()/rn_match() sequence while holding
reader-lock of "IPFW static rules" rwlock and newer got back.
Hence, all network activity broke as ipfw needs writer-lock of "IPFW
static rules".
Here comes backtrace of syslogd's kernel thread:
GNU gdb 6.1.1 [FreeBSD]
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB. Type "show warranty" for details.
This GDB was configured as "amd64-marcel-freebsd"...
Unread portion of the kernel message buffer:
KDB: enter: Break to debugger
Dumping 1135 out of 4079 MB:..2%..12%..22%..32%..41%..51%..61%..71%..81%..91%
Error while mapping shared library sections:
/boot/kernel/nfsclient.ko: îÅÔ ÔÁËÏÇÏ ÆÁÊÌÁ ÉÌÉ ËÁÔÁÌÏÇÁ.
Error while mapping shared library sections:
/boot/kernel/nfslock.ko: îÅÔ ÔÁËÏÇÏ ÆÁÊÌÁ ÉÌÉ ËÁÔÁÌÏÇÁ.
Error while mapping shared library sections:
/boot/kernel/nfs_common.ko: îÅÔ ÔÁËÏÇÏ ÆÁÊÌÁ ÉÌÉ ËÁÔÁÌÏÇÁ.
Error while mapping shared library sections:
/boot/kernel/krpc.ko: îÅÔ ÔÁËÏÇÏ ÆÁÊÌÁ ÉÌÉ ËÁÔÁÌÏÇÁ.
Reading symbols from /boot/kernel/ipmi.ko...done.
Loaded symbols for /boot/kernel/ipmi.ko
Error while reading shared library symbols:
/boot/kernel/nfsclient.ko: îÅÔ ÔÁËÏÇÏ ÆÁÊÌÁ ÉÌÉ ËÁÔÁÌÏÇÁ.
Error while reading shared library symbols:
/boot/kernel/nfslock.ko: îÅÔ ÔÁËÏÇÏ ÆÁÊÌÁ ÉÌÉ ËÁÔÁÌÏÇÁ.
Error while reading shared library symbols:
/boot/kernel/nfs_common.ko: îÅÔ ÔÁËÏÇÏ ÆÁÊÌÁ ÉÌÉ ËÁÔÁÌÏÇÁ.
Error while reading shared library symbols:
/boot/kernel/krpc.ko: îÅÔ ÔÁËÏÇÏ ÆÁÊÌÁ ÉÌÉ ËÁÔÁÌÏÇÁ.
#0 doadump () at /home/src/sys/kern/kern_shutdown.c:268
268 if (textdump_pending)
(kgdb) thread 134
[Switching to thread 134 (Thread 100201)]#0 sched_switch (
td=0xffffff0004e00470, newtd=0xffffff0001b96470, flags=Variable "flags" is
not available.
)
at /home/src/sys/kern/sched_ule.c:1892
1892 cpuid = PCPU_GET(cpuid);
(kgdb) bt
#0 sched_switch (td=0xffffff0004e00470, newtd=0xffffff0001b96470,
flags=Variable "flags" is not available.
)
at /home/src/sys/kern/sched_ule.c:1892
#1 0xffffffff80305c96 in mi_switch (flags=1538, newtd=0x0)
at /home/src/sys/kern/kern_synch.c:466
#2 0xffffffff803048f5 in critical_exit ()
at /home/src/sys/kern/kern_switch.c:212
#3 0xffffffff802d5733 in intr_event_handle (ie=0xffffff0001b61100,
frame=0xffffff81254122c0) at /home/src/sys/kern/kern_intr.c:1424
#4 0xffffffff804de4ff in intr_execute_handlers (isrc=0xffffff0001b82a00,
frame=0xffffff81254122c0) at /home/src/sys/amd64/amd64/intr_machdep.c:260
#5 0xffffffff804e2287 in lapic_handle_intr (vector=Variable "vector" is not
available.
)
at /home/src/sys/x86/x86/local_apic.c:771
#6 0xffffffff804db2b5 in Xapic_isr1 () at apic_vector.S:86
#7 0xffffffff803cdab3 in rn_match (v_arg=0xffffff81254123d0, head=Variable
"head" is not available.
)
at /home/src/sys/net/radix.c:352
#8 0xffffffff8040c03b in ipfw_lookup_table (ch=Variable "ch" is not available.
)
at /home/src/sys/netinet/ipfw/ip_fw_table.c:538
#9 0xffffffff80405e1f in ipfw_chk (args=0xffffff81254125a0)
at /home/src/sys/netinet/ipfw/ip_fw2.c:1429
#10 0xffffffff80409d7a in ipfw_check_hook (arg=Variable "arg" is not available.
)
at /home/src/sys/netinet/ipfw/ip_fw_pfil.c:137
#11 0xffffffff803cd46c in pfil_run_hooks (ph=Variable "ph" is not available.
) at /home/src/sys/net/pfil.c:82
#12 0xffffffff804127ca in ip_output (m=0xffffff00bdb5b000, opt=Variable "opt"
is not available.
)
at /home/src/sys/netinet/ip_output.c:511
#13 0xffffffff8042c115 in udp_send (so=Variable "so" is not available.
)
at /home/src/sys/netinet/udp_usrreq.c:1249
#14 0xffffffff803674cb in sosend_dgram (so=0xffffff0004e79550,
addr=0xffffff010c529060, uio=0xffffff8125412a00, top=0xffffff00bdb5b000,
control=0x0, flags=0, td=0xffffff0004e00470)
at /home/src/sys/kern/uipc_socket.c:1107
#15 0xffffffff8036b7e2 in kern_sendit (td=0xffffff0004e00470, s=7,
mp=0xffffff8125412ad0, flags=0, control=0x0, segflg=UIO_USERSPACE)
at /home/src/sys/kern/uipc_syscalls.c:785
#16 0xffffffff8036ba6c in sendit (td=0xffffff0004e00470, s=7,
mp=0xffffff8125412ad0, flags=0) at /home/src/sys/kern/uipc_syscalls.c:717
#17 0xffffffff8036bb5d in sendto (td=Variable "td" is not available.
)
at /home/src/sys/kern/uipc_syscalls.c:837
#18 0xffffffff804f3554 in amd64_syscall (td=0xffffff0004e00470, traced=0)
at subr_syscall.c:114
#19 0xffffffff804daefc in Xfast_syscall ()
at /home/src/sys/amd64/amd64/exception.S:387
#20 0x000000080082be3c in ?? ()
Previous frame inner to this frame (corrupt stack?)
(kgdb)
Backtraces of all kernel threads are available here:
http://www.grosbein.net/crash/20120929/misc.tar.xz
Kernel crashdump is also available at
http://www.grosbein.net/crash/20120929/
Here comes kernel config file:
cpu HAMMER
ident PPPOE
# To statically compile in device wiring instead of /boot/device.hints
#hints "GENERIC.hints" # Default places to look for devices.
# Use the following to compile in values accessible to the kernel
# through getenv() (or kenv(1) in userland). The format of the file
# is 'variable=value', see kenv(1)
#
# env "GENERIC.env"
makeoptions DEBUG=-g # Build kernel with gdb(1) debug symbols
options SCHED_ULE # ULE scheduler
options PREEMPTION # Enable kernel thread preemption
options INET # InterNETworking
options INET6 # IPv6 communications protocols
#options SCTP # Stream Control Transmission Protocol
options FFS # Berkeley Fast Filesystem
options SOFTUPDATES # Enable FFS soft updates support
options UFS_ACL # Support for access control lists
options UFS_DIRHASH # Improve performance on big directories
options UFS_GJOURNAL # Enable gjournal-based UFS journaling
options MD_ROOT # MD is a potential root device
#options NFSCLIENT # Network Filesystem Client
#options NFSSERVER # Network Filesystem Server
#options NFSLOCKD # Network Lock Manager
options NFS_ROOT # NFS usable as /, requires NFSCLIENT
#options MSDOSFS # MSDOS Filesystem
#options CD9660 # ISO 9660 Filesystem
#options PROCFS # Process filesystem (requires PSEUDOFS)
options PSEUDOFS # Pseudo-filesystem framework
options GEOM_PART_GPT # GUID Partition Tables.
options GEOM_LABEL # Provides labelization
#options GEOM_JOURNAL
options COMPAT_43TTY # BSD 4.3 TTY compat (sgtty)
options COMPAT_FREEBSD32 # Compatible with i386 binaries
#options COMPAT_FREEBSD4 # Compatible with FreeBSD4
#options COMPAT_FREEBSD5 # Compatible with FreeBSD5
#options COMPAT_FREEBSD6 # Compatible with FreeBSD6
#options COMPAT_FREEBSD7 # Compatible with FreeBSD7
#options SCSI_DELAY=5000 # Delay (in ms) before probing SCSI
options KTRACE # ktrace(1) support
options STACK # stack(9) support
options SYSVSHM # SYSV-style shared memory
options SYSVMSG # SYSV-style message queues
options SYSVSEM # SYSV-style semaphores
options P1003_1B_SEMAPHORES # POSIX-style semaphores
options _KPOSIX_PRIORITY_SCHEDULING # POSIX P1003_1B real-time
extensions
options PRINTF_BUFR_SIZE=512 # Prevent printf output being
interspersed.
options KBD_INSTALL_CDEV # install a CDEV entry in /dev
options HWPMC_HOOKS # Necessary kernel hooks for hwpmc(4)
options AUDIT # Security event auditing
options MAC # TrustedBSD MAC Framework
#options FLOWTABLE # per-cpu routing cache
#options KDTRACE_FRAME # Ensure frames are compiled in
#options KDTRACE_HOOKS # Kernel DTrace hooks
options INCLUDE_CONFIG_FILE # Include this file in kernel
# Make an SMP-capable kernel by default
options SMP # Symmetric MultiProcessor Kernel
# CPU frequency control
device cpufreq
# Bus support.
device acpi
device pci
# Floppy drives
#device fdc
# ATA and ATAPI devices
device ata
device atadisk # ATA disk drives
device atapicd # ATAPI CDROM drives
# SCSI peripherals
device scbus # SCSI bus (required for SCSI)
device da # Direct Access (disks)
device cd # CD
device pass # Passthrough device (direct SCSI access)
# atkbdc0 controls both the keyboard and the PS/2 mouse
device atkbdc # AT keyboard controller
device atkbd # AT keyboard
device psm # PS/2 mouse
device kbdmux # keyboard multiplexer
device vga # VGA video card driver
# syscons is the default console driver, resembling an SCO console
device sc
# Serial (COM) ports
device uart # Generic UART driver
# PCI Ethernet NICs.
device em # Intel PRO/1000 Gigabit Ethernet Family
device igb
# Pseudo devices.
device loop # Network loopback
device random # Entropy device
device ether # Ethernet support
device vlan # 802.1Q VLAN support
device pty # BSD-style compatibility pseudo ttys
device md # Memory "disks"
device gif # IPv6 and IPv4 tunneling
device faith # IPv6-to-IPv4 relaying (translation)
device firmware # firmware assist module
device snp
device bpf # Berkeley packet filter
# USB support
#options USB_DEBUG # enable debug msgs
#options USB_VERBOSE
device uhci # UHCI PCI->USB interface
device ehci # EHCI PCI->USB interface (USB 2.0)
device usb # USB Bus (required)
device ukbd # Keyboard
device umass # Disks/Mass storage - Requires scbus and da
device ums # Mouse
device ucom
# USB support for Prolific PL-2303 serial adapters
device uplcom
# USB support for Silicon Laboratories CP2101/CP2102 based USB serial adapters
device uslcom
#options IPSEC
#device crypto
options NETGRAPH
options NETGRAPH_ETHER
options NETGRAPH_IFACE
options NETGRAPH_MPPC_ENCRYPTION
options NETGRAPH_PPP
options NETGRAPH_PPPOE
options NETGRAPH_SOCKET
options NETGRAPH_TCPMSS
options NETGRAPH_TEE
options NETGRAPH_VJC
options IPFIREWALL
options IPFIREWALL_FORWARD
options DUMMYNET
options VFS_AIO
device smbus
device smb
device ichsmb
device iicbus
device iicbb
device ic
device iic
device iicsmb
device coretemp
device ichwd
device nvram
device lagg
options KDB
options KDB_TRACE
options KDB_UNATTENDED
options DDB
options DDB_NUMSYM
#options NETGRAPH_DEBUG
#options INVARIANT_SUPPORT
#options INVARIANTS
#options DEBUG_MEMGUARD
#options BREAK_TO_DEBUGGER
options ALT_BREAK_TO_DEBUGGER
device bridge
>How-To-Repeat:
Unknown. The problem occures very seldom but today was second time.
>Fix:
Unknown for me.
>Release-Note:
>Audit-Trail:
>Unformatted:
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