bash hangs after every command when running on Linux < 2.6.10

[Jonathan Riddell]

Bash 3.0-14ubuntu1 hangs on amd64 after any command taking up 99% CPU cycles. 3.0-13
did not have this problem.

x86 and ppc seem fine.

This was in a breezy chroot.

[Guido Nickels (gsn)]

definately broken. start a shell, execute a command and bash will immediately
hang and use 99% cpu.
affected package versions: 3.0-14ubuntu1

[Laurent Baillet (laurent-baillet)]

> Bash 3.0-14ubuntu1 hangs on amd64 after any command taking up 99% CPU cycles.
 3.0-13
> did not have this problem.
>
> x86 and ppc seem fine.

the problem occurs on a x86 too.

> This was in a breezy chroot.

[Colin Watson (cjwatson)]

I see this too. strace fragment as follows:

11411 exit_group(0) = ?
11408 <... waitpid resumed> 0x7ffff188, WUNTRACED|0x8) = -1 EINVAL (Invalid
argument)
11408 waitpid(-1, 0x7ffff188, WUNTRACED|0x8) = -1 EINVAL (Invalid argument)
[...]

I became curious as to what that mysterious 0x8 was, and found it in breezy's
/usr/include/bits/waitflags.h (but not in sid's). According to the waitpid(2)
man page, WCONTINUED is available only since Linux 2.6.10, and warty's kernel
has the following code at the top of sys_wait4():

        if (options & ~(WNOHANG|WUNTRACED|__WNOTHREAD|__WCLONE|__WALL))
                return -EINVAL;

If you can test for whether WCONTINUED is available at run-time, then that would
be best; otherwise, perhaps it would be best to disable use of WCONTINUED
entirely, if that doesn't cause significant breakage?

[Matthias Klose (doko)]

fixed in 3.0-15