On Thu, Jun 15, 2023 at 08:59:20AM -0400, Steven Rostedt wrote:
>
> Masami,
>
> Want to take this via your probes/urgent branch and send it off to Linus?
hi,
did this one make it into some tree?
thanks,
jirka
>
> -- Steve
>
>
> On Thu, 15 Jun 2023 13:52:36 +0200
> Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
>
> > While running bpf selftests it's possible to get following fault:
> >
> > general protection fault, probably for non-canonical address \
> > 0x6b6b6b6b6b6b6b6b: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC NOPTI
> > ...
> > Call Trace:
> > <TASK>
> > fprobe_handler+0xc1/0x270
> > ? __pfx_bpf_testmod_init+0x10/0x10
> > ? __pfx_bpf_testmod_init+0x10/0x10
> > ? bpf_fentry_test1+0x5/0x10
> > ? bpf_fentry_test1+0x5/0x10
> > ? bpf_testmod_init+0x22/0x80
> > ? do_one_initcall+0x63/0x2e0
> > ? rcu_is_watching+0xd/0x40
> > ? kmalloc_trace+0xaf/0xc0
> > ? do_init_module+0x60/0x250
> > ? __do_sys_finit_module+0xac/0x120
> > ? do_syscall_64+0x37/0x90
> > ? entry_SYSCALL_64_after_hwframe+0x72/0xdc
> > </TASK>
> >
> > In unregister_fprobe function we can't release fp->rethook while it's
> > possible there are some of its users still running on another cpu.
> >
> > Moving rethook_free call after fp->ops is unregistered with
> > unregister_ftrace_function call.
> >
> > Fixes: 5b0ab78998e3 ("fprobe: Add exit_handler support")
> > Reviewed-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
> > Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> > ---
> > kernel/trace/fprobe.c | 12 +++---------
> > 1 file changed, 3 insertions(+), 9 deletions(-)
> >
> > diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
> > index 18d36842faf5..0121e8c0d54e 100644
> > --- a/kernel/trace/fprobe.c
> > +++ b/kernel/trace/fprobe.c
> > @@ -364,19 +364,13 @@ int unregister_fprobe(struct fprobe *fp)
> > fp->ops.saved_func != fprobe_kprobe_handler))
> > return -EINVAL;
> >
> > - /*
> > - * rethook_free() starts disabling the rethook, but the rethook handlers
> > - * may be running on other processors at this point. To make sure that all
> > - * current running handlers are finished, call unregister_ftrace_function()
> > - * after this.
> > - */
> > - if (fp->rethook)
> > - rethook_free(fp->rethook);
> > -
> > ret = unregister_ftrace_function(&fp->ops);
> > if (ret < 0)
> > return ret;
> >
> > + if (fp->rethook)
> > + rethook_free(fp->rethook);
> > +
> > ftrace_free_filter(&fp->ops);
> >
> > return ret;
>
