Re: LOR in mpr(4)

On 11/12/15 09:44, Pete Wright wrote:
> Hi All,
> Just wanted a sanity check before filing a PR.  I am running r290688 and
> am seeing a LOR being triggered in the mpr(4) device:
> 
> $ uname -ar
> FreeBSD srd0013 11.0-CURRENT FreeBSD 11.0-CURRENT #1 r290688: Wed Nov 11
> 21:28:26 PST 2015     root_at_srd0013:/usr/obj/usr/src/sys/GENERIC  amd64
> 
> <dmesg snip>
> lock order reversal:
>  1st 0xfffff8000d26bc60 CAM device lock (CAM device lock) _at_
> /usr/src/sys/cam/cam_xpt.c:784
>  2nd 0xfffffe00012811c0 MPR lock (MPR lock) _at_
> /usr/src/sys/cam/cam_xpt.c:2620
> KDB: stack backtrace:
> db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame
> 0xfffffe04608ee890
> witness_checkorder() at witness_checkorder+0xe79/frame 0xfffffe04608ee910
> __mtx_lock_flags() at __mtx_lock_flags+0xa4/frame 0xfffffe04608ee960
> xpt_action_default() at xpt_action_default+0xb6c/frame 0xfffffe04608ee9b0
> scsi_scan_bus() at scsi_scan_bus+0x1d5/frame 0xfffffe04608eea20
> xpt_scanner_thread() at xpt_scanner_thread+0x15c/frame 0xfffffe04608eea70
> fork_exit() at fork_exit+0x84/frame 0xfffffe04608eeab0
> fork_trampoline() at fork_trampoline+0xe/frame 0xfffffe04608eeab0
> --- trap 0, rip = 0, rsp = 0, rbp = 0 ---
> <snip>

FWIW I filed the following PR as I can still reproduce this on boot:

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=204614

cheers,
-pete

-- 
Pete Wright
pete_at_nomadlogic.org
twitter => _at_nomadlogicLA