Re: Fatal trap 12: page fault while in kernel mode -- Stopped at atomic_subtract_int+0x4

Fabian Keil <freebsd-listen_at_fabiankeil.de> wrote:

> Fabian Keil <freebsd-listen_at_fabiankeil.de> wrote:
> 
> > I pretty reproducible get the following (handtranscribed) panic
> > when sending an zfs snapshot to geli provider based on an USB
> > stick that disappears (due to a bug, or because it's unplugged): 
> > 
> > Fatal trap 12: page fault while in kernel mode
> > cpuid = 0: apic id = 00
> > fault virtual address = 0x288
> > fault code	      = supervisor write data, page not present
> > instruction pointer   = 0x20:0xffffffff808e2984
> > stack pointer         = 0x28:0xffffff800023fba0
> > frame pointer         = 0x28:0xffffff800023fbb0
> > code segment          = base 0x0, limit 0xfffff, type 0x1b
> >                       = DPL 0, pres 1, long 1, def32 0, gran 1
> > processor eflags      = interrupt enabled, resume, IOPL = 0
> > current process       = 13 (g_up)
> > [ thread pid 13 tid 100010 ]
> > Stopped at    atomic_subtract_int+0x4: lock subl %esi,(%rdi)

> Here's another one, again with recent HEAD.
> 
> This time the USB stick disappeared while the pool was
> being scrubbed and dumping actually worked. The stick
> seems to reproducibly disappear after scrubbing it for
> a while and the panic seems to be reproducible as well.
> 
> The stack trace looks a bit different, but I'm not sure if
> this is because it's a slightly different situation or because
> of changes in HEAD.

They are different and can be reproduced independently.
I filed PRs for them:
http://www.freebsd.org/cgi/query-pr.cgi?pr=162010
http://www.freebsd.org/cgi/query-pr.cgi?pr=162036

Fabian