Re: panic: lock (sleep mutex) inp not locked

From: Jon Noack (noackjr_at_alumni.rice.edu)
Date: 11/29/04

  • Next message: Christian Brueffer: "Re: panic: lock (sleep mutex) inp not locked" 
    Date: Sun, 28 Nov 2004 17:34:20 -0600
To: Christian Brueffer <chris@unixpages.org>

    On 11/28/04 17:07, Christian Brueffer wrote:
    > Hi,
    >
    > got this panic today on an SMP system. Modifications to the kernel are
    > polling and altq support for the sf driver and removed SMP ifdefs from
    > sys/kern/kern_poll.c.
    >
    > FreeBSD haakonia.hitnet.RWTH-Aachen.DE 5.3-STABLE FreeBSD 5.3-STABLE #61: Sat Nov 27 02:59:01 CET 2004
    > chris@haakonia.hitnet.RWTH-Aachen.DE:/usr/home/build/usr/home/build/src/sys/LORIEN i386
    >
    > Sources are from November 22nd.
    >
    > Crashdump and debug kernel are available for further investigation.
    >
    > panic: lock (sleep mutex) inp not locked @ /usr/home/build/src/sys/netinet/tcp_input.c:2521
    > cpuid = 1
    > KDB: enter: panic
    > [thread 100034]
    > Stopped at kdb_enter+0x2b: nop
    > db> tr
    > kdb_enter(c06c6c54) at kdb_enter+0x2b
    > panic(c06caa02,c06db3d0,c06d57ce,c06d2493,9d9) at panic+0x127
    > witness_unlock(c3f4d57c,8,c06d2493,9d9) at witness_unlock+0xbc
    > _mtx_unlock_flags(c3f4d57c,0,c06d2493,9d9,0) at _mtx_unlock_flags+0x5b
    > tcp_input(c44bb000,14,5cb5e289,0,0) at tcp_input+0x2fb0
    > ip_input(c44bb000) at ip_input+0x52d
    > netisr_dispatch(2,c44bb000,0,c44b0800,c1a93c00) at netisr_dispatch+0x58
    > ether_demux(c1a93c00,c44bb000,297,96,d74f6400) at ether_demux+0x292
    > ether_input(c1a93c00,c44bb000,c1a93e84,0,c0833d13) at ether_input+0x269
    > sf_rxeof(c1a93c00,c1a93c00,c1a93e84,c07276c0,d543ecbc) at sf_rxeof+0x183
    > sf_poll_locked(c1a93c00,0,5,c1a93e84,0) at sf_poll_locked+0x6b
    > sf_poll(c1a93c00,0,5) at sf_poll+0x2e
    > netisr_poll(0) at netisr_poll+0x188
    > swi_net(0) at swi_net+0x81
    > ithread_loop(c19e1080,d543ed48,c19e1080,c051aa34,0) at
    > ithread_loop+0x124
    > fork_exit(c051aa34,c19e1080,d543ed48) at fork_exit+0xa4
    > fork_trampoline() at fork_trampoline+0x8
    > --- trap 0x1, eip = 0, esp = 0xd543ed7c, ebp = 0 ---
    > db> show locks
    > exclusive sleep mutex tcp r = 0 (0xc0755dac) locked @
    > /usr/home/build/src/sys/netinet/tcp_input.c:617
    > exclusive sleep mutex Giant r = 1 (0xc0728320) locked @
    > /usr/home/build/src/sys/kern/kern_poll.c:332
    > db> show pcpu
    > cpuid = 1
    > curthread = 0xc19e3640: pid 38 "swi1: net"
    > curpcb = 0xd543eda0
    > fpcurthread = none
    > idlethread = 0xc19a84b0: pid 11 "idle: cpu1"
    > APIC ID = 1
    > currentldt = 0x28
    > spin locks held:
    > db>

    I successfully used polling on my SMP machine a while back, but it
    pessimized performance for my workloads so I disabled it. All I did was
    to wrap the SMP error in /sys/kern/kern_poll.c with #ifdef 0...#endif
    and everything worked.

    In any case, it seems rwatson@ is interested in polling on SMP; check
    out his netperf page (http://www.watson.org/~robert/freebsd/netperf/)
    for more info. Specifically, the following entry in his 20041103 patch
    is of interest:

    "A mutex to protect device polling state is introduced, pollmtx, and
       used to protect the global variables present in kern_poll.c. As a
       result, Giant is removed from the polling netisr code, and the
       #ifdef causing polling build to fail on SMP is removed. This has
       not been tested."

    No idea whether or not it works, but I thought I'd give you a heads up.

    Jon
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