Messages in this thread | | | Subject | Re: __ftrace_hash_rec_update FTRACE_WARN_ON. | From | Steven Rostedt <> | Date | Thu, 25 Jul 2013 14:59:01 -0400 |
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On Wed, 2013-07-24 at 22:46 -0700, Steve Hodgson wrote:
> 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.
It's not stupid. ftrace should be robust enough to handle this. Anyway, thank you, I found a reproducer.
Removing the module isn't good enough. You need to load it again.
# cd /sys/kernel/debug/tracing # cat set_ftrace_filter #### all functions enabled #### # modprobe uinput # echo uniput_release > set_ftrace_filter # cat set_ftrace_filter uinput_release [uinput] # rmmod uinput # cat set_ftrace_filter # # note this is empty # modprobe uinput # cat set_ftrace_filter uinput_release [uinput] # # '<it magically appeared>' # echo > set_ftrace_filter [BOOM]
Now that I know what's the problem, it shouldn't be too hard to fix.
Thanks!
-- Steve
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