Lock order reversal: em0 and Giant

[Scott Long]

Josh Tolbert wrote:
> Hi,
> 
> FreeBSD 5.3-RELEASE-p5 on a Tyan Tiger LE with two PIII/733s an
> Intel Pro/1000MT 64-bit NIC in a 66MHz PCI slot nets me these
> repeatedly on boot immediately after the interface comes up:
> 
> Apr 26 09:57:56 ram kernel: em0: Link is up 1000 Mbps Full Duplex
> Apr 26 09:57:56 ram kernel: lock order reversal
> Apr 26 09:57:56 ram kernel: 1st 0xc162e3b4 em0 (network driver) @ /usr/src/sys/dev/em/if_em.c:980
> Apr 26 09:57:56 ram kernel: 2nd 0xc0663d80 Giant (Giant) @ /usr/src/sys/vm/vm_contig.c:538
> Apr 26 09:57:56 ram kernel: KDB: stack backtrace:
> Apr 26 09:57:56 ram kernel: kdb_backtrace(c0619e00,c0663d80,c0615a3e,c0615a3e,c06270aa) at kdb_backtrace+0x2e
> Apr 26 09:57:56 ram kernel: witness_checkorder(c0663d80,9,c06270aa,21a,d403d964) at witness_checkorder+0x6a6
> Apr 26 09:57:56 ram kernel: _mtx_lock_flags(c0663d80,0,c06270aa,21a,c04b9b5f) at _mtx_lock_flags+0x8a
> Apr 26 09:57:56 ram kernel: contigmalloc(1000,c063d760,1,0,ffffffff) at contigmalloc+0x42
> Apr 26 09:57:56 ram kernel: alloc_bounce_pages(c1737d00,4,101,c18ac100,c162e000) at alloc_bounce_pages+0x83
> Apr 26 09:57:56 ram kernel: bus_dmamap_create(c1737d00,1,d403da28,c0672c20,0) at bus_dmamap_create+0x131
> Apr 26 09:57:56 ram kernel: em_encap(c162e000,c18ac100,c0609329,267,c162e0e8) at em_encap+0x90
> Apr 26 09:57:56 ram kernel: em_start_locked(c162e000,ffffffff,c044cfc0,c162e000,c162e37c) at em_start_locked+0x254
> Apr 26 09:57:56 ram kernel: em_intr(c162e000,0,c0613eaa,269,c0663d40) at em_intr+0x143
> Apr 26 09:57:56 ram kernel: ithread_loop(c1566400,d403dd48,c0613cce,323,b20684f9) at ithread_loop+0x172
> Apr 26 09:57:56 ram kernel: fork_exit(c04b0410,c1566400,d403dd48) at fork_exit+0xc6
> Apr 26 09:57:56 ram kernel: fork_trampoline() at fork_trampoline+0x8 
> Apr 26 09:57:56 ram kernel: --- trap 0x1, eip = 0, esp = 0xd403dd7c, ebp = 0 ---
> 
> If there's any other information you need, please let me know.
> 
> Thanks,
> Josh

Crumbs, I'll look at this.  Can you provide some details of your system?
dmesg?  Could you also provide the output of 'sysctl hw.busdma'?  Thanks,

Scott