From mboxrd@z Thu Jan 1 00:00:00 1970 From: mathieu.desnoyers@efficios.com (Mathieu Desnoyers) Date: Thu, 23 Apr 2015 20:13:29 +0000 (UTC) Subject: [lttng-dev] [BUG] lttng-sessiond In-Reply-To: <1230298824.35208.1429817200877.JavaMail.zimbra@efficios.com> References: <3E06425C-5C41-4BF7-8156-A62C4E9B5E60@mailbox.tu-dresden.de> <1230298824.35208.1429817200877.JavaMail.zimbra@efficios.com> Message-ID: <1795330554.35257.1429820009277.JavaMail.zimbra@efficios.com> ----- Original Message ----- > ----- Original Message ----- > > Hello, > > > > I'm using LTTng with a kernel that has lock debugging enabled. I > > familiarized myself with LTTng using the "Hello world" example, where > > I encountered two bugs. > > Hi Hannes, > > Can you share with us the code of your "hello" probe ? > > Which version or git commit of lttng-modules are you > using ? I think the two issues should be fixed by this new git commit in lttng-modules master branch: commit 66fd8d5e4a6080f1b2db0f525c26c07e5b723aab Author: Mathieu Desnoyers Date: Thu Apr 23 16:11:15 2015 -0400 Fix: double-unlock of session mutex Signed-off-by: Mathieu Desnoyers Can you give it a try ? Thanks! Mathieu > > Thanks, > > Mathieu > > > > > 1) Using multiple probes for the lttng-sessiond arguments > > --kmod-probes and --extra-kmod-probes does not work: > > > > $ sudo lttng-sessiond --kmod-probes="hello,sched" -vvv > > [...] > > DEBUG1 - 11:54:22.413830 [17827/17827]: Modprobe successfully > > lttng-probe-sched (in modprobe_lttng() at modprobe.c:285) > > sh: 1: Syntax error: "(" unexpected > > DEBUG1 - 11:54:22.415273 [17827/17827]: Unable to load optional module > > (null); continuing (in modprobe_lttng() at modprobe.c:281) > > [...] > > > > $ sudo lttng-sessiond --kmod-probes="sched,hello" -vvv > > [...] > > DEBUG1 - 11:55:13.879976 [17896/17896]: Modprobe successfully > > lttng-probe-hello (in modprobe_lttng() at modprobe.c:285) > > sh: 1: Syntax error: "(" unexpected > > DEBUG1 - 11:55:13.881183 [17896/17896]: Unable to load optional module > > (null); continuing (in modprobe_lttng() at modprobe.c:281) > > [...] > > > > $ sudo lttng-sessiond --extra-kmod-probes="sched,hello" -vvv > > [...] > > DEBUG1 - 11:55:54.244515 [17966/17966]: Modprobe successfully > > lttng-probe-hello (in modprobe_lttng() at modprobe.c:285) > > sh: 1: Syntax error: "(" unexpected > > DEBUG1 - 11:55:54.245758 [17966/17966]: Unable to load optional module > > (null); continuing (in modprobe_lttng() at modprobe.c:281) > > [...] > > > > It seems, only the last argument (module) is loaded correctly. > > > > 2) Having lttng-sessiond started: > > $ sudo lttng-sessiond --kmod-probes=hello > > And the tracer configured: > > lttng create > > lttng enable-event hello_world -k > > > > 'lttng start' causes a locking failure to be reported: > > [ 159.783420] > > [ 159.783922] ===================================== > > [ 159.784067] [ BUG: bad unlock balance detected! ] > > [ 159.784067] 4.0.0-rc4-atlas+ #200 Tainted: G O > > [ 159.784067] ------------------------------------- > > [ 159.784067] lttng-sessiond/1441 is trying to release lock > > (sessions_mutex) > > at: > > [ 159.784067] [] mutex_unlock+0xe/0x10 > > [ 159.784067] but there are no more locks to release! > > [ 159.784067] > > [ 159.784067] other info that might help us debug this: > > [ 159.784067] no locks held by lttng-sessiond/1441. > > [ 159.784067] > > [ 159.784067] stack backtrace: > > [ 159.784067] CPU: 0 PID: 1441 Comm: lttng-sessiond Tainted: G O > > 4.0.0-rc4-atlas+ #200 > > [ 159.784067] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS > > Bochs 01/01/2011 > > [ 159.784067] ffffffff81808c3e ffff88005d24fa28 ffffffff818029e0 > > 0000000000000007 > > [ 159.784067] ffff880057c9cd60 ffff88005d24fa58 ffffffff810c1924 > > ffff88005d24fad8 > > [ 159.784067] ffff880057c9cd60 ffffffffa01ce070 ffffffff81808c3e > > ffff88005d24fa98 > > [ 159.784067] Call Trace: > > [ 159.784067] [] ? mutex_unlock+0xe/0x10 > > [ 159.784067] [] dump_stack+0x4c/0x65 > > [ 159.784067] [] print_unlock_imbalance_bug+0xf4/0x100 > > [ 159.784067] [] ? mutex_unlock+0xe/0x10 > > [ 159.784067] [] lock_release+0x2e6/0x460 > > [ 159.784067] [] __mutex_unlock_slowpath+0x76/0x190 > > [ 159.784067] [] mutex_unlock+0xe/0x10 > > [ 159.784067] [] lttng_session_enable+0x208/0x5b0 > > [lttng_tracer] > > [ 159.784067] [] lttng_session_ioctl+0x155/0x300 > > [lttng_tracer] > > [ 159.784067] [] ? __lock_acquire+0x570/0x1f60 > > [ 159.784067] [] ? sched_clock_local+0x25/0x90 > > [ 159.784067] [] ? do_wp_page+0x3a7/0x900 > > [ 159.784067] [] ? sched_clock_cpu+0x98/0xc0 > > [ 159.784067] [] ? local_clock+0x15/0x30 > > [ 159.784067] [] ? sched_clock_local+0x25/0x90 > > [ 159.784067] [] ? do_wp_page+0x3a7/0x900 > > [ 159.784067] [] ? __lock_acquire+0x570/0x1f60 > > [ 159.784067] [] ? do_wp_page+0x3a7/0x900 > > [ 159.784067] [] ? handle_mm_fault+0x310/0x18b0 > > [ 159.784067] [] ? sched_clock_local+0x25/0x90 > > [ 159.784067] [] ? sched_clock_local+0x25/0x90 > > [ 159.784067] [] ? __fget+0x111/0x260 > > [ 159.784067] [] ? sched_clock_cpu+0x98/0xc0 > > [ 159.784067] [] ? local_clock+0x15/0x30 > > [ 159.784067] [] ? __fget+0x111/0x260 > > [ 159.784067] [] do_vfs_ioctl+0x308/0x560 > > [ 159.784067] [] ? __fget+0x5/0x260 > > [ 159.784067] [] ? __do_page_fault+0x1f1/0x4c0 > > [ 159.784067] [] SyS_ioctl+0x81/0xa0 > > [ 159.784067] [] system_call_fastpath+0x16/0x1b > > > > I hope this helps. > > > > -- > > Best regards, > > Hannes > > > > _______________________________________________ > > lttng-dev mailing list > > lttng-dev at lists.lttng.org > > http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev > > > > -- > Mathieu Desnoyers > EfficiOS Inc. > http://www.efficios.com > > _______________________________________________ > lttng-dev mailing list > lttng-dev at lists.lttng.org > http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev > -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com