Date: Tue, 07 Nov 2017 12:15:22 +0100 From: Andreas Longwitz <longwitz@incore.de> To: Mark Johnston <markj@FreeBSD.org> Cc: "freebsd-dtrace@freebsd.org" <freebsd-dtrace@freebsd.org> Subject: Re: dtrace pid provider on entry == Trace/BPT trap process Message-ID: <5A0195CA.2010907@incore.de> In-Reply-To: <20170905144154.GC65864@wkstn-mjohnston.west.isilon.com> References: <59AE834E.1090700@incore.de> <20170905144154.GC65864@wkstn-mjohnston.west.isilon.com>
next in thread | previous in thread | raw e-mail | index | archive | help
Maybe the following is of interest for DTrace experts:
>> I use FreeBSD 10.3-STABLE r317936 with updated /usr/lib/dtrace/ip.c and
>> see an issue that in my opinion should have been solved in r269342:
>
> 10.3 would be missing a number of other fixes for issues that might
> cause the symptom you're seeing. Unfortunately, userland DTrace is not
> very usable on FreeBSD before 11.0.
I have repeated my looptest on a server running FreeBSD 12.0-CURRENT #0
r324306 with GENERIC kernel. I saw the same problem as described before
for FreeBSD 10.3-Stable r317936:
Nov 7 10:54:09 <kern.info> dssbkp2 kernel: pid 38041 (looptest), uid
1003: exited on signal 5
Further I saw following error message from dtrace:
dtrace: failed to grab pid 38622: Device busy.
After some minutes playing around the server crashed with
panic: PHOLD of exiting process 0xfffff80004c80540
cpuid = 0
time = 1510051083
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame
0xfffffe0231e22700
vpanic() at vpanic+0x19c/frame 0xfffffe0231e22780
kassert_panic() at kassert_panic+0x126/frame 0xfffffe0231e227f0
uread() at uread+0x173/frame 0xfffffe0231e22830
fasttrap_tracepoint_remove() at fasttrap_tracepoint_remove+0x23/frame
0xfffffe0231e22860
fasttrap_tracepoint_disable() at fasttrap_tracepoint_disable+0x31a/frame
0xfffffe0231e228d0
fasttrap_pid_disable() at fasttrap_pid_disable+0x8e/frame 0xfffffe0231e22910
dtrace_ecb_disable() at dtrace_ecb_disable+0x11c/frame 0xfffffe0231e22940
dtrace_state_destroy() at dtrace_state_destroy+0x169/frame
0xfffffe0231e22980
dtrace_dtr() at dtrace_dtr+0x63/frame 0xfffffe0231e229a0
devfs_destroy_cdevpriv() at devfs_destroy_cdevpriv+0x8b/frame
0xfffffe0231e229c0
devfs_close_f() at devfs_close_f+0x65/frame 0xfffffe0231e229f0
closef() at closef+0x1f5/frame 0xfffffe0231e22a80
closefp() at closefp+0x9f/frame 0xfffffe0231e22ac0
amd64_syscall() at amd64_syscall+0x79b/frame 0xfffffe0231e22bf0
Xfast_syscall() at Xfast_syscall+0xfb/frame 0xfffffe0231e22bf0
--- syscall (6, FreeBSD ELF64, sys_close), rip = 0x80128f47a, rsp =
0x7fffffffe878, rbp = 0x7fffffffe890 ---
>> I run a simple program looptest, that loops around a sprintf() call and
>> want to check this program with
>>
>> dtrace -n 'pid$target:libc.so.*::entry {@[probefunc] = count();}' -p
>> $(pgrep looptest)
>> dtrace: description 'pid$target:libc.so.*::entry ' matched 3863 probes
>>
>> After some seconds I hit CTRL-C and see
>>
>> __vfprintf 741685
>> localeconv_l 741685
>> memset 741685
>> sprintf 741685
>> vsprintf 741685
>> __sfvwrite 1483369
>> memcpy 2225052
>>
>> and at the same time looptest stops with
>> Trace/BPT trap (Speicherabzug geschrieben)
>> and on the console I see the kernel message
>> pid 67550 (looptest), uid 1003: exited on signal 5 (core dumped)
>>
>> The trap does not occur all the time, but it is no problem to repeat the
>> trap.
--
Andreas Longwitz
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?5A0195CA.2010907>