Re: s390 && user_enable_single_step() (Was: odd utrace testing results on s390x)

Oleg Nesterov
2010-01-05T19:58:29Z

On 01/05, Oleg Nesterov wrote:
>
> On 01/05, Oleg Nesterov wrote:
> >
> > I'll add clear_bit(TIF_SINGLE_STEP) into do_fork() path and re-test.
>
> Hmm. This patch
>
> --- kernel/fork.c~ 2009-12-22 10:41:53.188084961 -0500
> +++ kernel/fork.c 2010-01-05 11:42:58.370636323 -0500
> @@ -1206,6 +1206,8 @@ static struct task_struct *copy_process(
> * of CLONE_PTRACE.
> */
> clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
> + clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
> + user_disable_single_step(p);
> #ifdef TIF_SYSCALL_EMU
> clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
> #endif
>
> doesn't help, I still see the same XXX's in dmesg...

Oh, now I am totally confused.

I reverted your fix from
https://www.redhat.com/archives/utrace-devel/2010-January/msg00006.html
and now there is nothing in dmesg.

I decided to re-test this all with vanilla 2.6.33-rc2. It is really
amazing how long it takes to recompile/install the kernel! I spent
the rest of this day fighting with this rhts machine. Result - it
doesn't boot:

00: zIPL v1.8.2-5.el6 interactive boot menu
00:
00: 0. default (2.6.33-rc2)
00:
00: 1. 2.6.33-rc2
00: 2. 2.6.32.2-14.s390x.el6.s390x
00: 3. 2.6.32.2-14.el6.s390x
00: 4. linux
00:
00: Note: VM users please use '#cp vi vmsg '
00:
00: Please choose (default will boot in 15 seconds):
00: Booting default (2.6.33-rc2)...
Ý<000000000011c4fc>¨ sysc_return+0x0/0x8
Ý<00000000003cc0c6>¨ selinux_sb_copy_data+0x17e/0x238
(Ý<00000000003cbf94>¨ selinux_sb_copy_data+0x4c/0x238)
Ý<00000000003b62a6>¨ security_sb_copy_data+0x4e/0x60
Ý<0000000000280338>¨ vfs_kern_mount+0x19c/0x1f4
Ý<00000000002803de>¨ kern_mount_data+0x4e/0x5c
Ý<0000000000ae1908>¨ devtmpfs_init+0x60/0xbc
Ý<0000000000ae1818>¨ driver_init+0x28/0x6c
Ý<0000000000abe582>¨ kernel_init+0x32a/0x3d8
Ý<000000000010b8c2>¨ kernel_thread_starter+0x6/0xc
Ý<000000000010b8bc>¨ kernel_thread_starter+0x0/0xc
INFO: lockdep is turned off.
00: HCPGIR450W CP entered; disabled wait PSW 00020001 80000000 00000000 00114BD4
00:
00:
00:
00:
00:
00:

Cai, any chance you can help? Using /usr/bin/console I can't choose another
kernel at the "00: Please choose (default will boot in 15 seconds):" stage,
how can I do this???

Oleg.