RPI2, panic: pmap_fault: PT2MAP abort

[bob prohaska]

Has anybody else seen a panic on RPI2 that  looks  like this?

r322942 was building world on r323029. 

This happened a couple of days ago, the panic repeated on restart but
went away using an old kernel and the system built successfully. _That_
system then built r323029, so I thought the problem was solved.

A web search on the panic message didn't produce any recent hits, only
one from about a year ago.

Here's the console output:

panic: pmap_fault: PT2MAP abort
cpuid = 2
time = 1504234464
KDB: stack backtrace:
db_trace_self() at db_trace_self
	 pc = 0xc05a2a04  lr = 0xc0155b6c (db_trace_self_wrapper+0x30)
	 sp = 0xc1e68a98  fp = 0xc1e68bb0
db_trace_self_wrapper() at db_trace_self_wrapper+0x30
	 pc = 0xc0155b6c  lr = 0xc02de7c4 (vpanic+0x158)
	 sp = 0xc1e68bb8  fp = 0xc1e68bd8
	 r4 = 0x00000100  r5 = 0x00000001
	 r6 = 0xc0671211  r7 = 0xc086f1f0
vpanic() at vpanic+0x158
	 pc = 0xc02de7c4  lr = 0xc02de834 (kproc_shutdown)
	 sp = 0xc1e68be0  fp = 0xc1e68be4
	 r4 = 0x00000000  r5 = 0xbfc909ac
	 r6 = 0xc3cfeb04  r7 = 0x00000007
	 r8 = 0x00000013  r9 = 0xc09072e0
	r10 = 0x00000007
kproc_shutdown() at kproc_shutdown
	 pc = 0xc02de834  lr = 0xc05bcefc (pmap_fault+0x410)
	 sp = 0xc1e68bec  fp = 0xc1e68c18
	 r4 = 0xc02de834  r5 = 0xc1e68bec
pmap_fault() at pmap_fault+0x410
	 pc = 0xc05bcefc  lr = 0xc05c12f4 (abort_handler+0xec)
	 sp = 0xc1e68c20  fp = 0xc1e68cb0
	 r4 = 0x056210c0  r5 = 0xbfc909ac
	 r6 = 0x00000007  r7 = 0x00000007
	 r8 = 0x00000013  r9 = 0x00000000
	r10 = 0xc1e68cb8
abort_handler() at abort_handler+0xec
	 pc = 0xc05c12f4  lr = 0xc05a53dc (exception_exit)
	 sp = 0xc1e68cb8  fp = 0xc1e68d68
	 r4 = 0x00000001  r5 = 0x2426bff0
	 r6 = 0xc3cfeb04  r7 = 0x00000006
	 r8 = 0xc3cfeb14  r9 = 0xc09072e0
	r10 = 0x00000806
exception_exit() at exception_exit
	 pc = 0xc05a53dc  lr = 0xc02c4478 (__mtx_lock_flags+0x138)
	 sp = 0xc1e68d48  fp = 0xc1e68d68
	 r0 = 0x000909ac  r1 = 0xbfc00000
	 r2 = 0x00000000  r3 = 0xffffffff
	 r4 = 0x00000001  r5 = 0x2426bff0
	 r6 = 0xc3cfeb04  r7 = 0x00000006
	 r8 = 0xc3cfeb14  r9 = 0xc09072e0
	r10 = 0x00000806 r12 = 0xc0670a57
pmap_fault() at pmap_fault+0xd0
	 pc = 0xc05bcbbc  lr = 0xc05c12f4 (abort_handler+0xec)
	 sp = 0xc1e68d70  fp = 0xc1e68e00
	 r4 = 0x056210bf  r5 = 0x2426bff0
	 r6 = 0x00000006  r7 = 0x00000806
	 r8 = 0x00000010  r9 = 0x00000000
	r10 = 0xc1e68e08
abort_handler() at abort_handler+0xec
	 pc = 0xc05c12f4  lr = 0xc05a53dc (exception_exit)
	 sp = 0xc1e68e08  fp = 0xbfbfd108
	 r4 = 0x2423a008  r5 = 0x2423a024
	 r6 = 0x00000001  r7 = 0x00000005
	 r8 = 0x2423a008  r9 = 0x2426bff0
	r10 = 0x2423a0f0
exception_exit() at exception_exit
	 pc = 0xc05a53dc  lr = 0x034ee574 (0x34ee574)
	 sp = 0xc1e68e98  fp = 0xbfbfd108
	 r0 = 0x2426bff0  r1 = 0x00000010
	 r2 = 0x5a5a5a5a  r3 = 0x5a5a5a5a
	 r4 = 0x2423a008  r5 = 0x2423a024
	 r6 = 0x00000001  r7 = 0x00000005
	 r8 = 0x2423a008  r9 = 0x2426bff0
	r10 = 0x2423a0f0 r12 = 0x2426bff0
Unable to unwind into user mode
KDB: enter: panic
[ thread pid 35088 tid 100113 ]
Stopped at      $d.3:   ldrb    r15, [r15, r15, ror r15]!
db> 

Thanks for reading, and any insights....

bob prohaska