On Wed, Jul 24, 2013 at 6:24 PM, Steven Rostedt <rost...@goodmis.org> wrote: > > On Wed, 2013-07-24 at 12:04 -0400, Jörn Engel wrote: > > On Fri, 5 July 2013 10:53:54 -0400, Steven Rostedt wrote: > > > > > > Can you find an easy reproducer for this? > > > > We might have found something: > > > > Jul 23 19:00:59 [28253.487058,08] WARNING: at kernel/trace/ftrace.c:1529 > > __ftrace_hash_rec_update+0x1e3/0x230() > > Jul 23 19:00:59 [28253.487203,08] Pid: 20903, comm: bash Tainted: G > > O 3.6.11+ #38405.trunk > > Jul 23 19:00:59 [28253.487206,08] Call Trace: > > Jul 23 19:00:59 [28253.487213,08] [<ffffffff8103e5ff>] > > warn_slowpath_common+0x7f/0xc0 > > Jul 23 19:00:59 [28253.487218,08] [<ffffffff8103e65a>] > > warn_slowpath_null+0x1a/0x20 > > Jul 23 19:00:59 [28253.487222,08] [<ffffffff810c2ee3>] > > __ftrace_hash_rec_update+0x1e3/0x230 > > Jul 23 19:00:59 [28253.487227,08] [<ffffffff810c4f28>] > > ftrace_hash_move+0x28/0x1d0 > > Jul 23 19:00:59 [28253.487232,08] [<ffffffff811401cc>] ? kfree+0x2c/0x110 > > Jul 23 19:00:59 [28253.487237,08] [<ffffffff810c68ee>] > > ftrace_regex_release+0x8e/0x150 > > Jul 23 19:00:59 [28253.487242,08] [<ffffffff81149f1e>] __fput+0xae/0x220 > > Jul 23 19:00:59 [28253.487247,08] [<ffffffff8114a09e>] ____fput+0xe/0x10 > > Jul 23 19:00:59 [28253.487252,08] [<ffffffff8105fa22>] > > task_work_run+0x72/0x90 > > Jul 23 19:00:59 [28253.487257,08] [<ffffffff810028ec>] > > do_notify_resume+0x6c/0xc0 > > Jul 23 19:00:59 [28253.487262,08] [<ffffffff8126596e>] ? > > trace_hardirqs_on_thunk+0x3a/0x3c > > Jul 23 19:00:59 [28253.487267,08] [<ffffffff815c0f88>] int_signal+0x12/0x17 > > Jul 23 19:00:59 [28253.487271,08] ---[ end trace 793179526ee09b2c ]--- > > > > Jul 23 19:21:02 [ 775.393547,08] WARNING: at kernel/trace/ftrace.c:1529 > > __ftrace_hash_rec_update+0x1e3/0x230() > > Jul 23 19:21:02 [ 775.393715,08] Pid: 6376, comm: bash Tainted: G > > O 3.6.11+ #38405.trunk > > Jul 23 19:21:02 [ 775.393718,08] Call Trace: > > Jul 23 19:21:02 [ 775.393727,08] [<ffffffff8103e5ff>] > > warn_slowpath_common+0x7f/0xc0 > > Jul 23 19:21:02 [ 775.393732,08] [<ffffffff8103e65a>] > > warn_slowpath_null+0x1a/0x20 > > Jul 23 19:21:02 [ 775.393737,08] [<ffffffff810c2ee3>] > > __ftrace_hash_rec_update+0x1e3/0x230 > > Jul 23 19:21:02 [ 775.393741,08] [<ffffffff810c4f28>] > > ftrace_hash_move+0x28/0x1d0 > > Jul 23 19:21:02 [ 775.393748,08] [<ffffffff811401cc>] ? kfree+0x2c/0x110 > > Jul 23 19:21:02 [ 775.393754,08] [<ffffffff810c68ee>] > > ftrace_regex_release+0x8e/0x150 > > Jul 23 19:21:02 [ 775.393771,08] [<ffffffff81149f1e>] __fput+0xae/0x220 > > Jul 23 19:21:02 [ 775.393784,08] [<ffffffff8114a09e>] ____fput+0xe/0x10 > > Jul 23 19:21:02 [ 775.393792,08] [<ffffffff8105fa22>] > > task_work_run+0x72/0x90 > > Jul 23 19:21:02 [ 775.393798,08] [<ffffffff810028ec>] > > do_notify_resume+0x6c/0xc0 > > Jul 23 19:21:02 [ 775.393804,08] [<ffffffff8126596e>] ? > > trace_hardirqs_on_thunk+0x3a/0x3c > > Jul 23 19:21:02 [ 775.393810,08] [<ffffffff815c0f88>] int_signal+0x12/0x17 > > Jul 23 19:21:02 [ 775.393814,08] ---[ end trace 3b86cc549cc5483e ]--- > > > > If I understand Steve correctly, you have to enable a trace somewhere > > in a module, them rmmod that module without disabling the trace. Easy > > enough to avoid, but maybe you are interested. > > I'm a bit confused by this. What do you mean exactly by enable a trace > somewhere in a module? The module enables the trace? Does it have its > own ftrace_ops? Or the module just starts tracing?
No, nothing so complicated. I added symbols from a kernel module into /sys/kernel/debug/tracing/set_ftrace_filter, enabled tracing, then unloaded the kernel module. Which I'll admit is a stupid thing to do. I was then punished for my stupidity by being unable to use ftrace until the next reboot. - Steve -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
