svn commit: r253687 - head/sys/net

[Andrey V. Elsukov]

On 25.04.2014 19:58, Alan Somers wrote:
> On Fri, Jul 26, 2013 at 1:41 PM, Adrian Chadd <adrian at freebsd.org> wrote:
>> Author: adrian
>> Date: Fri Jul 26 19:41:13 2013
>> New Revision: 253687
>> URL: http://svnweb.freebsd.org/changeset/base/253687
>>
>> Log:
>>   Break out the static, global LACP debug options into a per-lagg unit
>>   sysctl tree.
>>
>>   * Create a net.link.lagg.X.lacp node
> 
> I think this introduced a lock order reversal.
> 
>>   * Add a debug node under that for tx_test and rx_test
>>   * Add lacp_strict_mode, defaulting to 1
>>
>>   tx_test and rx_test are still a bitmap of unit numbers for now.
>>   At some point it would be nice to create child nodes of the lagg bundle
>>   for each sub-interface, and then populate those with various knobs
>>   and statistics.
>>
>>   Sponsored by: Netflix
>>
>> Modified:
>>   head/sys/net/ieee8023ad_lacp.c
>>   head/sys/net/ieee8023ad_lacp.h
>>   head/sys/net/if_lagg.c
>>   head/sys/net/if_lagg.h
>>
>> Modified: head/sys/net/ieee8023ad_lacp.c
>> ==============================================================================
>> --- head/sys/net/ieee8023ad_lacp.c      Fri Jul 26 19:11:08 2013        (r253686)
>> +++ head/sys/net/ieee8023ad_lacp.c      Fri Jul 26 19:41:13 2013        (r253687)
> 
> <Extra chunks elided>
> ;
>> @@ -765,10 +791,19 @@ lacp_attach(struct lagg_softc *sc)
>>
>>         lsc->lsc_hashkey = arc4random();
>>         lsc->lsc_active_aggregator = NULL;
>> +       lsc->lsc_strict_mode = 1;
>>         LACP_LOCK_INIT(lsc);
>>         TAILQ_INIT(&lsc->lsc_aggregators);
>>         LIST_INIT(&lsc->lsc_ports);
>>
>> +       /* Create a child of the parent lagg interface */
>> +       oid = SYSCTL_ADD_NODE(&sc->ctx, SYSCTL_CHILDREN(sc->sc_oid),
>> +           OID_AUTO, "lacp", CTLFLAG_RD, NULL, "LACP");
> 
> This line grabs a sleepable lock, but we already had a nonsleepable
> lock further up the stack, acquired in lagg_ioctl().
> 
>> +
>> +       /* Attach sysctl nodes */
>> +       lacp_attach_sysctl(lsc, oid);
>> +       lacp_attach_sysctl_debug(lsc, oid);
>> +
>>         callout_init_mtx(&lsc->lsc_transit_callout, &lsc->lsc_mtx, 0);
>>         callout_init_mtx(&lsc->lsc_callout, &lsc->lsc_mtx, 0);
>>
> 
> Here's the warning from Witness.as well as a warning from UMA.  Many
> more UMA warnings followed.
> 
> lock order reversal: (sleepable after non-sleepable)
> 1st 0xfffff8000252ca08 if_lagg rmlock (if_lagg rmlock) @
> /usr/home/alans/freebsd/head/sys/modules/if_lagg/../../net/if_lagg.c:1040
> 2nd 0xffffffff814ef4e0 sysctl lock (sysctl lock) @
> /usr/home/alans/freebsd/head/sys/kern/kern_sysctl.c:474
> KDB: stack backtrace:
> db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe00977485b0
> kdb_backtrace() at kdb_backtrace+0x39/frame 0xfffffe0097748660
> witness_checkorder() at witness_checkorder+0xdc2/frame 0xfffffe00977486f0
> _sx_xlock() at _sx_xlock+0x75/frame 0xfffffe0097748730
> sysctl_add_oid() at sysctl_add_oid+0x4a/frame 0xfffffe0097748780
> lacp_attach() at lacp_attach+0xf7/frame 0xfffffe00977487f0
> lagg_lacp_attach() at lagg_lacp_attach+0x88/frame 0xfffffe0097748810
> lagg_ioctl() at lagg_ioctl+0x98a/frame 0xfffffe00977488f0
> in_control() at in_control+0x38e/frame 0xfffffe0097748970
> ifioctl() at ifioctl+0xba2/frame 0xfffffe0097748a30
> kern_ioctl() at kern_ioctl+0x22b/frame 0xfffffe0097748a90
> sys_ioctl() at sys_ioctl+0x13c/frame 0xfffffe0097748ae0
> amd64_syscall() at amd64_syscall+0x25a/frame 0xfffffe0097748bf0
> Xfast_syscall() at Xfast_syscall+0xfb/frame 0xfffffe0097748bf0
> --- syscall (54, FreeBSD ELF64, sys_ioctl), rip = 0x800fa045a, rsp =
> 0x7fffffffe118, rbp = 0x7fffffffe1a0 ---
> uma_zalloc_arg: zone "128" with the following non-sleepable locks held:
> exclusive rm if_lagg rmlock (if_lagg rmlock) r = 0
> (0xfffff8000252ca08) locked @
> /usr/home/alans/freebsd/head/sys/modules/if_lagg/../../net/if_lagg.c:1040
> KDB: stack backtrace:
> db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe0097748500
> kdb_backtrace() at kdb_backtrace+0x39/frame 0xfffffe00977485b0
> witness_warn() at witness_warn+0x4b5/frame 0xfffffe0097748670
> uma_zalloc_arg() at uma_zalloc_arg+0x3b/frame 0xfffffe00977486e0
> malloc() at malloc+0x194/frame 0xfffffe0097748730
> sysctl_add_oid() at sysctl_add_oid+0x11f/frame 0xfffffe0097748780
> lacp_attach() at lacp_attach+0xf7/frame 0xfffffe00977487f0
> lagg_lacp_attach() at lagg_lacp_attach+0x88/frame 0xfffffe0097748810
> lagg_ioctl() at lagg_ioctl+0x98a/frame 0xfffffe00977488f0
> in_control() at in_control+0x38e/frame 0xfffffe0097748970
> ifioctl() at ifioctl+0xba2/frame 0xfffffe0097748a30
> kern_ioctl() at kern_ioctl+0x22b/frame 0xfffffe0097748a90
> sys_ioctl() at sys_ioctl+0x13c/frame 0xfffffe0097748ae0
> amd64_syscall() at amd64_syscall+0x25a/frame 0xfffffe0097748bf0
> Xfast_syscall() at Xfast_syscall+0xfb/frame 0xfffffe0097748bf0
> --- syscall (54, FreeBSD ELF64, sys_ioctl), rip = 0x800fa045a, rsp =
> 0x7fffffffe118, rbp = 0x7fffffffe1a0 ---
> 
> 
> # uname -a
> FreeBSD alans-fbsd-head 11.0-CURRENT FreeBSD 11.0-CURRENT #49
> r264887M: Thu Apr 24 17:21:48 MDT 2014
> alans at ns1.eng.sldomain.com:/vmpool/obj/usr/home/alans/freebsd/head/sys/GENERIC
>  amd64
> 
> To reproduce:
> ifconfig tap0 create
> ifconfig tap1 create
> ifconfig tap2 create
> ifconfig lagg0 create
> ifconfig lagg0 up laggproto lacp laggport tap0 laggport tap1 laggport
> tap2 192.0.0.2/24
> 
> If I create and destroy the lagg in a tight loop, while running
> "ifconfig -am" in a tight loop in another terminal, I eventually hit a
> general protection fault in __mtx_lock_sleep.  I think it might be
> related.

Do you have a backtrace from this panic?

> Can you reproduce this?  Do you have any good ideas for a solution?

I can reproduce a lot of LOR messages, but no panic.

-- 
WBR, Andrey V. Elsukov