On Sat, Jan 15, 2022 at 01:52:19PM +0900, Masami Hiramatsu wrote:
> On Thu, 13 Jan 2022 13:27:34 +0100
> Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
>
> > On Wed, Jan 12, 2022 at 05:01:15PM +0100, Jiri Olsa wrote:
> > > On Wed, Jan 12, 2022 at 11:02:46PM +0900, Masami Hiramatsu wrote:
> > > > Hi Jiri and Alexei,
> > > >
> > > > Here is the 2nd version of fprobe. This version uses the
> > > > ftrace_set_filter_ips() for reducing the registering overhead.
> > > > Note that this also drops per-probe point private data, which
> > > > is not used anyway.
> > > >
> > > > This introduces the fprobe, the function entry/exit probe with
> > > > multiple probe point support. This also introduces the rethook
> > > > for hooking function return as same as kretprobe does. This
> > >
> > > nice, I was going through the multi-user-graph support
> > > and was wondering that this might be a better way
> > >
> > > > abstraction will help us to generalize the fgraph tracer,
> > > > because we can just switch it from rethook in fprobe, depending
> > > > on the kernel configuration.
> > > >
> > > > The patch [1/8] and [7/8] are from your series[1]. Other libbpf
> > > > patches will not be affected by this change.
> > >
> > > I'll try the bpf selftests on top of this
> >
> > I'm getting crash and stall when running bpf selftests,
> > the fprobe sample module works fine, I'll check on that
>
> OK, I got a kernel stall. I missed to enable CONFIG_FPROBE.
> I think vmtest.sh should support menuconfig option.
>
> #6 bind_perm:OK
> #7 bloom_filter_map:OK
> [ 107.282403] clocksource: timekeeping watchdog on CPU0: Marking clocksource 'tsc' as unstable because the skew is too large:
> [ 107.283240] clocksource: 'hpet' wd_nsec: 496216090 wd_now: 7ddc7120 wd_last: 7ae746b7 mask: ffffffff
> [ 107.284045] clocksource: 'tsc' cs_nsec: 495996979 cs_now: 31fdb69b39 cs_last: 31c2d29219 mask: ffffffffffffffff
> [ 107.284926] clocksource: 'tsc' is current clocksource.
> [ 107.285487] tsc: Marking TSC unstable due to clocksource watchdog
> [ 107.285973] TSC found unstable after boot, most likely due to broken BIOS. Use 'tsc=unstable'.
> [ 107.286616] sched_clock: Marking unstable (107240582544, 45390230)<-(107291410145, -5437339)
> [ 107.290408] clocksource: Not enough CPUs to check clocksource 'tsc'.
> [ 107.290879] clocksource: Switched to clocksource hpet
> [ 604.210415] INFO: rcu_tasks detected stalls on tasks:
> [ 604.210830] (____ptrval____): .. nvcsw: 86/86 holdout: 1 idle_cpu: -1/0
> [ 604.211314] task:test_progs state:R running task stack: 0 pid: 87 ppid: 85 flags:0x00004000
> [ 604.212058] Call Trace:
> [ 604.212246] <TASK>
> [ 604.212452] __schedule+0x362/0xbb0
> [ 604.212723] ? preempt_schedule_notrace_thunk+0x16/0x18
> [ 604.213107] preempt_schedule_notrace+0x48/0x80
> [ 604.217403] ? asm_sysvec_apic_timer_interrupt+0x12/0x20
> [ 604.217790] ? ftrace_regs_call+0xd/0x52
> [ 604.218087] ? bpf_test_finish.isra.0+0x190/0x190
> [ 604.218461] ? bpf_fentry_test1+0x5/0x10
> [ 604.218750] ? trace_clock_x86_tsc+0x10/0x10
> [ 604.219064] ? __sys_bpf+0x8b1/0x2970
> [ 604.219337] ? lock_is_held_type+0xd7/0x130
> [ 604.219680] ? __x64_sys_bpf+0x1c/0x20
> [ 604.219957] ? do_syscall_64+0x35/0x80
> [ 604.220237] ? entry_SYSCALL_64_after_hwframe+0x44/0xae
> [ 604.220653] </TASK>
>
> Jiri, is that what you had seen?
hi,
sorry for late response
I did not get any backtrace for the stall, debugging showed
that the first probed function was called over and over for
some reason
as for the crash I used the small fix below
do you have any newer version I could play with?
jirka
---
diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
index 3333893e5217..883151275892 100644
--- a/kernel/trace/fprobe.c
+++ b/kernel/trace/fprobe.c
@@ -157,7 +157,8 @@ int unregister_fprobe(struct fprobe *fp)
ret = unregister_ftrace_function(&fp->ftrace);
if (!ret) {
- rethook_free(fp->rethook);
+ if (fp->rethook)
+ rethook_free(fp->rethook);
if (fp->syms) {
kfree(fp->addrs);
fp->addrs = NULL;
