Date: Wed, 24 Jan 2001 11:29:30 -0800 (PST) From: John Baldwin <jhb@FreeBSD.ORG> To: Andrew Gallatin <gallatin@cs.duke.edu> Cc: freebsd-alpha@FreeBSD.ORG Subject: RE: -current failing on PC164 Message-ID: <XFMail.010124112930.jhb@FreeBSD.org> In-Reply-To: <14959.10557.921381.576255@grasshopper.cs.duke.edu>
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On 24-Jan-01 Andrew Gallatin wrote:
>
> OK.. After a re-configure, I get this:
>
> Mounting root from ufs:/dev/da0a
> da0 at sym0 bus 0 target 0 lun 0
> da0: <SEAGATE ST39140W 1498> Fixed Direct Access SCSI-2 device
> da0: 40.000MB/s transfers (20.000MHz, offset 15, 16bit), Tagged
> Queueing Enabled
> da0: 8683MB (17783240 512 byte sectors: 255H 63S/T 1106C)
> panic: mutex_enter(sio:1, MTX_SPIN) out of order @
> ../../isa/sio.c:2287 already holding sched lock:2
So we already hold sched_lock and are obtaining sio_lock.
Looks like it is trying to display a printf while holding sched_lock?
At ddb, can you examine sched_lock, find its mtx_debug member:
struct mtx {
volatile uintptr_t mtx_lock; /* lock owner/gate/flags */
volatile u_int mtx_recurse; /* number of recursive holds */
u_int mtx_saveintr; /* saved flags (for spin locks)
*/
int mtx_flags; /* flags passed to mtx_init() */
const char *mtx_description;
TAILQ_HEAD(, proc) mtx_blocked;
LIST_ENTRY(mtx) mtx_contested;
struct mtx *mtx_next; /* all locks in system */
struct mtx *mtx_prev;
struct mtx_debug *mtx_debug;
};
Then examine the memory at mtx_debug to find the mtxd_line and
mtxd_file members:
struct mtx_debug {
struct witness *mtxd_witness;
LIST_ENTRY(mtx) mtxd_held;
const char *mtxd_file;
int mtxd_line;
};
Which should tell us the file and line of the last time sched_lock was
obtained. Hopefully from that we can figure out what printf is
triggering this..
> I don't understand the panic message -- why is it talking about sched
> lock when the mtx_enter is on sio_lock??
It is complaining that the mutex enter on sio is invalid because
sched_lock is already held and that this violates the lock order.
> Cheers,
>
> Drew
--
John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/
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