i was able to get an strace from powrtop (loo\gging in by ssh from a scrr\een session on a remote computer) and attach the log here.  it looks like the issue is triggered by  "iwpriv -a" -- here's what looks like the relevant part of the log (at the end):

[pid  2077] execve("/bin/sh", ["sh", "-c", "/sbin/iwpriv -a 2> /dev/null"], [/* 19 vars */] <unfinished ...>
[pid  2064] mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f884e1ea000
[pid  2064] read(4,  <unfinished ...>
[pid  2077] <... execve resumed> )      = 0
[pid  2077] brk(0)                      = 0x2590000
[pid  2077] access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
[pid  2077] mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f5d2ef07000
[pid  2077] access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
[pid  2077] open("/etc/ld.so.cache", O_RDONLY) = 4
[pid  2077] fstat(4, {st_mode=S_IFREG|0644, st_size=131558, ...}) = 0
[pid  2077] mmap(NULL, 131558, PROT_READ, MAP_PRIVATE, 4, 0) = 0x7f5d2eee6000
[pid  2077] close(4)                    = 0
[pid  2077] access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
[pid  2077] open("/lib/libc.so.6", O_RDONLY) = 4
[pid  2077] read(4, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0`\355\1\0\0\0\0\0"..., 832) = 832
[pid  2077] fstat(4, {st_mode=S_IFREG|0755, st_size=1572232, ...}) = 0
[pid  2077] mmap(NULL, 3680296, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 4, 0) = 0x7f5d2e966000
[pid  2077] mprotect(0x7f5d2eae0000, 2093056, PROT_NONE) = 0
[pid  2077] mmap(0x7f5d2ecdf000, 20480, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 4, 0x179000) = 0x7f5d2ecdf000
[pid  2077] mmap(0x7f5d2ece4000, 18472, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f5d2ece4000
[pid  2077] close(4)                    = 0
[pid  2077] mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f5d2eee5000
[pid  2077] mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f5d2eee4000
[pid  2077] mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f5d2eee3000
[pid  2077] arch_prctl(ARCH_SET_FS, 0x7f5d2eee4700) = 0
[pid  2077] mprotect(0x7f5d2ecdf000, 16384, PROT_READ) = 0
[pid  2077] mprotect(0x617000, 4096, PROT_READ) = 0
[pid  2077] mprotect(0x7f5d2ef09000, 4096, PROT_READ) = 0
[pid  2077] munmap(0x7f5d2eee6000, 131558) = 0
[pid  2077] getpid()                    = 2077
[pid  2077] rt_sigaction(SIGCHLD, {SIG_DFL, [CHLD], SA_RESTORER|SA_RESTART, 0x7f5d2e999af0}, {SIG_DFL, [], 0}, 8) = 0
[pid  2077] geteuid()                   = 0
[pid  2077] brk(0)                      = 0x2590000
[pid  2077] brk(0x25b1000)              = 0x25b1000
[pid  2077] getppid()                   = 2064
[pid  2077] stat("/root", {st_mode=S_IFDIR|0700, st_size=4096, ...}) = 0
[pid  2077] stat(".", {st_mode=S_IFDIR|0700, st_size=4096, ...}) = 0
[pid  2077] rt_sigaction(SIGINT, NULL, {SIG_DFL, [], 0}, 8) = 0
[pid  2077] rt_sigaction(SIGINT, {0x408189, ~[RTMIN RT_1], SA_RESTORER, 0x7f5d2e999af0}, NULL, 8) = 0
[pid  2077] rt_sigaction(SIGQUIT, NULL, {SIG_DFL, [], 0}, 8) = 0
[pid  2077] rt_sigaction(SIGQUIT, {SIG_DFL, ~[RTMIN RT_1], SA_RESTORER, 0x7f5d2e999af0}, NULL, 8) = 0
[pid  2077] rt_sigaction(SIGTERM, NULL, {SIG_DFL, [], 0}, 8) = 0
[pid  2077] rt_sigaction(SIGTERM, {SIG_DFL, ~[RTMIN RT_1], SA_RESTORER, 0x7f5d2e999af0}, NULL, 8) = 0
[pid  2077] open("/dev/null", O_WRONLY|O_CREAT|O_TRUNC, 0666) = 4
[pid  2077] fcntl(2, F_DUPFD, 10)       = 10
[pid  2077] close(2)                    = 0
[pid  2077] fcntl(10, F_SETFD, FD_CLOEXEC) = 0
[pid  2077] dup2(4, 2)                  = 2
[pid  2077] close(4)                    = 0
[pid  2077] clone(Process 2078 attached
child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7f5d2eee49d0) = 2078
[pid  2077] wait4(-1,  <unfinished ...>
[pid  2078] execve("/sbin/iwpriv", ["/sbin/iwpriv", "-a"], [/* 19 vars */]

----------------------------------------------

running iwpriv -a manually results in a kernel panic and the following error message:

lo         no private ioctls.
eth0     no private ioctls.
wlan0   Available read-only private ioctl :
wlan0   firm_ver:63 
Kernel Panic [etc...]

-------------

so, what do i do next?  any suggestions?  And can other people confirm this error?