Re: [PATCHSET] ptrace,signal: group stop / ptrace updates

From: Ingo Molnar
Date: Fri Jan 28 2011 - 11:55:26 EST


I'm hijacking this thread, to report a signal handling bug that Linux and Bash has,
and which has been there at least for 10 years since i started using SMP Linux
systems ...

It's not easy to reproduce but today i found a reproducer - maybe you guys have an
idea what's going on.

There's two very simple scripts, one calls the other in an infinite loop:

$ cat test-signal

while true; do ./test-signal2; done

$ cat test-signal2


The bug is that occasionally Ctrl-C does not get processed, and that the Ctrl-C is
'lost'. It can be reproduced here by running ./test-signal several times, and
Ctrl-C-ing it:

$ ./test-signal
$ ./test-signal
$ ./test-signal

See that '^C^C' line? That is where i had to do Ctrl-C twice.

It only fails here about once every 10 times, so it's very rare. I have a stock F14
system running on that box, with the very latest .38 based kernel.

Any ideas what's going on?


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at