flowtable_cleaner/flowtable_flush livelock

[Mikolaj Golub]

On Sat, 20 Nov 2010 17:03:13 +0000 (UTC) Bjoern A. Zeeb wrote:

 BAZ> I think net@ would have been a better initial place but since this
 BAZ> seems to be a problem when interacting with VIMAGE
 BAZ> freebsd-virtualization might be better.

 BAZ> What you could try is:
 BAZ> http://people.freebsd.org/~bz/20100216-10-ft-cv.diff

Ah, I have recalled I had already saw this patch but did not understand what
the problem was that it fixed, thus did not associated it with my case
(actually, I thought you had committed all these patches to the tree long time
ago and I was running the kernel with them already :-).

BTW, the patch needs updating: in the current flow_full() wakes up flowcleaner
too, and flowcleaner sleeps for flowclean_freq instead of 10*hz (see the
attached patch).

With the patch I can't reproduce the lock. Only the crash I mentioned in my
first letter is observed:

(kgdb) bt
#0  doadump () at pcpu.h:231
#1  0xc04f2789 in db_fncall (dummy1=1, dummy2=0, dummy3=-1056677760, dummy4=0xc8731860 "")
    at /usr/src/sys/ddb/db_command.c:548
#2  0xc04f2b81 in db_command (last_cmdp=0xc0e79f7c, cmd_table=0x0, dopager=1)
    at /usr/src/sys/ddb/db_command.c:445
#3  0xc04f2cda in db_command_loop () at /usr/src/sys/ddb/db_command.c:498
#4  0xc04f4bfd in db_trap (type=12, code=0) at /usr/src/sys/ddb/db_main.c:229
#5  0xc09119be in kdb_trap (type=12, code=0, tf=0xc8731a94) at /usr/src/sys/kern/subr_kdb.c:546
#6  0xc0c3da8f in trap_fatal (frame=0xc8731a94, eva=3735929074)
    at /usr/src/sys/i386/i386/trap.c:970
#7  0xc0c3e0be in trap (frame=0xc8731a94) at /usr/src/sys/i386/i386/trap.c:361
#8  0xc0c272dc in calltrap () at /usr/src/sys/i386/i386/exception.s:168
#9  0xc0988415 in strncmp (s1=0xc1fee4e0 "epair20b", 
    s2=0xdeadc0f2 <Address 0xdeadc0f2 out of bounds>, n=16) at /usr/src/sys/libkern/strncmp.c:44
#10 0xc09929d7 in ifunit_ref (name=0xc1fee4e0 "epair20b") at /usr/src/sys/net/if.c:1986
#11 0xc0996982 in ifioctl (so=0xc25649c0, cmd=3223349536, data=0xc1fee4e0 "epair20b", 
    td=0xc286c000) at /usr/src/sys/net/if.c:2475
#12 0xc09307f7 in soo_ioctl (fp=0xc1ff5af0, cmd=3223349536, data=0xc1fee4e0, 
    active_cred=0xc1d83e80, td=0xc286c000) at /usr/src/sys/kern/sys_socket.c:212
#13 0xc092a61d in kern_ioctl (td=0xc286c000, fd=3, com=3223349536, data=0xc1fee4e0 "epair20b")
    at file.h:254
#14 0xc092a7a4 in ioctl (td=0xc286c000, uap=0xc8731cec) at /usr/src/sys/kern/sys_generic.c:679
#15 0xc091f303 in syscallenter (td=0xc286c000, sa=0xc8731ce4)
    at /usr/src/sys/kern/subr_trap.c:318
#16 0xc0c3dd2f in syscall (frame=0xc8731d28) at /usr/src/sys/i386/i386/trap.c:1094
#17 0xc0c27371 in Xint0x80_syscall () at /usr/src/sys/i386/i386/exception.s:266
#18 0x00000033 in ?? ()
Previous frame inner to this frame (corrupt stack?)
(kgdb) fr 10
#10 0xc09929d7 in ifunit_ref (name=0xc1fee4e0 "epair20b") at /usr/src/sys/net/if.c:1986
1986                    if (strncmp(name, ifp->if_xname, IFNAMSIZ) == 0 &&
(kgdb) p ifp
$1 = (struct ifnet *) 0xdeadc0de

I might want to report it to freebsd-virtualization unless I find that this is
a known issue.

-- 
Mikolaj Golub

-------------- next part --------------
A non-text attachment was scrubbed...
Name: 20101120-10-ft-cv.diff
Type: text/x-patch
Size: 2061 bytes
Desc: not available
Url : http://lists.freebsd.org/pipermail/freebsd-hackers/attachments/20101120/5699232b/20101120-10-ft-cv.bin