Ok, so ntpd does not respond to a SIGQUIT with a core dump but I did
manage to attach a trace to the process before killing it. The output
of ktrace is below. The circumstances of this particular lockup I was
actually able to observe. I camped out at the system waiting.
A cron job fired off which does routine disk maintenance (diffs of
config files, free space calculations, postfix cleanup, etc.) In this
case things got swapped around a bit while all the cleanup was occuring.
However, after those activities finished, ntpd never returned to
normal. It just spun out of control resulting in the trace below. Other
programs that were running at the same time (gpsd, xclock, xterm) all
recovered cleanly though the system was now bogged down by ntpd
consuming almost all the processor time even though it was not set to
high priority. The capture below pretty much loops continuously until
ntpd is finally killed. I actually let the system run for an additional
24 hours in this state just to see if it would bounce back but it never
did. I killed only one process, ntpd, and everything else was fine as
the CPU load dropped to near zero immediately.
1210 1 ntpd CALL clock_gettime(0,0xefffd0e8)
1210 1 ntpd RET clock_gettime 0, -268447512/0xefffd0e8
1210 1 ntpd CALL select(0x1c,0xefffd05c,0,0,0xefffd0b4)
1210 1 ntpd RET select 1, -268447652/0xefffd05c
1210 1 ntpd CALL
recvfrom(0x16,0xefffcc74,0x3e8,0,0xefffd098,0xefffd0ec)
1210 1 ntpd MISC msghdr: 28,
00000000f02cf7e0f25edeac00000001000000000001b58400000000
1210 1 ntpd GIO fd 22 read 12 bytes
"\^V\^A\0\^A\0\0\0\0\0\0\0\0"
1210 1 ntpd MISC sockname: 16, 1002de040a00008d0000000000000000
1210 1 ntpd RET recvfrom 12/0xc, -268448652/0xefffcc74
1210 1 ntpd CALL
recvfrom(0x16,0xefffcc74,0x3e8,0,0xefffd098,0xefffd0ec)
1210 1 ntpd MISC msghdr: 28,
00000000f02cf7e0f25edeac00000001000000000001b58400000000
1210 1 ntpd RET recvfrom -1 errno 35 Resource temporarily
unavailable
1210 1 ntpd CALL setcontext(0xefffd248)
1210 1 ntpd RET setcontext JUSTRETURN
1210 1 ntpd PSIG SIGALRM caught handler=0x3ea2c mask=():
code=SI_TIMER sigval 0x3)
1210 1 ntpd CALL setcontext(0xefffd248)
1210 1 ntpd RET setcontext JUSTRETURN
1210 1 ntpd PSIG SIGALRM caught handler=0x3ea2c mask=():
code=SI_TIMER sigval 0x3)
1210 1 ntpd CALL setcontext(0xefffd248)
1210 1 ntpd RET setcontext JUSTRETURN
1210 1 ntpd PSIG SIGALRM caught handler=0x3ea2c mask=():
code=SI_TIMER sigval 0x3)
1210 1 ntpd CALL setcontext(0xefffd248)
1210 1 ntpd RET setcontext JUSTRETURN
1210 1 ntpd PSIG SIGALRM caught handler=0x3ea2c mask=():
code=SI_TIMER sigval 0x3)
1210 1 ntpd CALL setcontext(0xefffd178)
1210 1 ntpd RET setcontext JUSTRETURN
1210 1 ntpd PSIG SIGALRM caught handler=0x3ea2c mask=():
code=SI_TIMER sigval 0x3)
1210 1 ntpd CALL setcontext(0xefffd248)
1210 1 ntpd RET setcontext JUSTRETURN
1210 1 ntpd PSIG SIGALRM caught handler=0x3ea2c mask=():
code=SI_TIMER sigval 0x3)
1210 1 ntpd CALL setcontext(0xefffd178)
1210 1 ntpd RET setcontext JUSTRETURN
1210 1 ntpd PSIG SIGALRM caught handler=0x3ea2c mask=():
code=SI_TIMER sigval 0x3)
1210 1 ntpd CALL setcontext(0xefffd178)
1210 1 ntpd RET setcontext JUSTRETURN
1210 1 ntpd PSIG SIGALRM caught handler=0x3ea2c mask=():
code=SI_TIMER sigval 0x3)
1210 1 ntpd CALL setcontext(0xefffd178)
1210 1 ntpd RET setcontext JUSTRETURN
1210 1 ntpd PSIG SIGALRM caught handler=0x3ea2c mask=():
code=SI_TIMER sigval 0x3)
1210 1 ntpd CALL setcontext(0xefffd248)
1210 1 ntpd RET setcontext JUSTRETURN
1210 1 ntpd PSIG SIGIO caught handler=0x6b670 mask=():
code=[1], fd=22, band=41)
1210 1 ntpd PSIG SIGALRM caught handler=0x3ea2c mask=(23):
code=SI_TIMER sigval 0x3)
1210 1 ntpd CALL setcontext(0xefffce00)
1210 1 ntpd RET setcontext JUSTRETURN
1210 1 ntpd CALL clock_gettime(0,0xefffd018)
1210 1 ntpd RET clock_gettime 0, -268447720/0xefffd018
1210 1 ntpd PSIG SIGALRM caught handler=0x3ea2c mask=(23):
code=SI_TIMER sigval 0x3)
1210 1 ntpd CALL setcontext(0xefffcdf8)
1210 1 ntpd RET setcontext JUSTRETURN
1210 1 ntpd CALL select(0x1c,0xefffcf8c,0,0,0xefffcfe4)
1210 1 ntpd RET select 1, -268447860/0xefffcf8c
1210 1 ntpd CALL
recvfrom(0x16,0xefffcba4,0x3e8,0,0xefffcfc8,0xefffd01c)
1210 1 ntpd MISC msghdr: 28,
00000000f02cf7e0f25edeac00000001000000001039485c00000000
1210 1 ntpd GIO fd 22 read 12 bytes
"\^V\^A\0\^A\0\0\0\0\0\0\0\0"
1210 1 ntpd MISC sockname: 16, 1002e7210a00008d0000000000000000
1210 1 ntpd RET recvfrom 12/0xc, -268448860/0xefffcba4
1210 1 ntpd CALL
recvfrom(0x16,0xefffcba4,0x3e8,0,0xefffcfc8,0xefffd01c)
1210 1 ntpd MISC msghdr: 28,
00000000f02cf7e0f25edeac00000001000000001039485c00000000
1210 1 ntpd RET recvfrom -1 errno 35 Resource temporarily
unavailable
1210 1 ntpd CALL setcontext(0xefffd178)
1210 1 ntpd RET setcontext JUSTRETURN
1210 1 ntpd PSIG SIGALRM caught handler=0x3ea2c mask=():
code=SI_TIMER sigval 0x3)
1210 1 ntpd CALL setcontext(0xefffd248)
1210 1 ntpd RET setcontext JUSTRETURN
1210 1 ntpd PSIG SIGALRM caught handler=0x3ea2c mask=():
code=SI_TIMER sigval 0x3)
1210 1 ntpd CALL setcontext(0xefffd248)
1210 1 ntpd RET setcontext JUSTRETURN
1210 1 ntpd PSIG SIGALRM caught handler=0x3ea2c mask=():
code=SI_TIMER sigval 0x3)
1210 1 ntpd CALL setcontext(0xefffd248)
1210 1 ntpd RET setcontext JUSTRETURN
1210 1 ntpd PSIG SIGIO caught handler=0x6b670 mask=():
code=[1], fd=22, band=41)
1210 1 ntpd CALL clock_gettime(0,0xefffd0e8)
1210 1 ntpd RET clock_gettime 0, -268447512/0xefffd0e8
1210 1 ntpd PSIG SIGALRM caught handler=0x3ea2c mask=(23):
code=SI_TIMER sigval 0x3)
1210 1 ntpd CALL setcontext(0xefffcec8)
1210 1 ntpd RET setcontext JUSTRETURN
1210 1 ntpd CALL select(0x1c,0xefffd05c,0,0,0xefffd0b4)
1210 1 ntpd RET select 1, -268447652/0xefffd05c
1210 1 ntpd CALL
recvfrom(0x16,0xefffcc74,0x3e8,0,0xefffd098,0xefffd0ec)
1210 1 ntpd MISC msghdr: 28,
00000000f02cf7e0f25edeac00000001000000000001b58400000000
1210 1 ntpd GIO fd 22 read 12 bytes
"\^V\^A\0\^A\0\0\0\0\0\0\0\0"
1210 1 ntpd MISC sockname: 16, 1002e7210a00008d0000000000000000
1210 1 ntpd RET recvfrom 12/0xc, -268448652/0xefffcc74
1210 1 ntpd CALL
recvfrom(0x16,0xefffcc74,0x3e8,0,0xefffd098,0xefffd0ec)
1210 1 ntpd MISC msghdr: 28,
00000000f02cf7e0f25edeac00000001000000000001b58400000000
1210 1 ntpd RET recvfrom -1 errno 35 Resource temporarily
unavailable
1210 1 ntpd CALL setcontext(0xefffd248)
1210 1 ntpd RET setcontext JUSTRETURN
1210 1 ntpd PSIG SIGALRM caught handler=0x3ea2c mask=():
code=SI_TIMER sigval 0x3)
1210 1 ntpd CALL setcontext(0xefffd248)
1210 1 ntpd RET setcontext JUSTRETURN
1210 1 ntpd PSIG SIGALRM caught handler=0x3ea2c mask=():
code=SI_TIMER sigval 0x3)
1210 1 ntpd CALL setcontext(0xefffd178)
1210 1 ntpd RET setcontext JUSTRETURN
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