Re: PROBLEM: 2.6test11 kernel panic on "head -1 /proc/net/tcp"

From: lkml-031128
Date: Fri Dec 05 2003 - 06:24:40 EST

OGAWA Hirofumi wrote:
lkml-031128@xxxxxxxxxxxxxxxxxx writes:

After I added Ogawa's line, "head -1 /proc/net/tcp" stopped
freezing my machine but PPP failed to work.

Also after adding Ogawa's line, PPP works fine (as it is now, as
I write this message) as long as I don't try "head -1 /proc/net/tcp"
after boot. If I'll try "head -1 /proc/net/tcp" now PPP will stop

Can you reproduce the fail of PPP? I couldn't reproduce it.
What reason is the fail of PPP? (the "debug" option of pppd may be helpful)

Sorry. I just tried:

1. From a multi-user mode, after an uptime of 5 days (test11 with your
2. killed the ppp daemon (/etc/init.d/ppp stop). Made sure the ppp0
interface is down.
3. did "head -1 /proc/net/tcp" and "cat /proc/net/tcp". Passed fine.
4. re-startted ppp daemon.
5. System is fine. No kernel errors. PPP works flowlessly.

So I think my linking of PPP to the fix was wrong. Maybe the PPP failure
was unrelated to this.

Of course, the following message is easy reproducible. But it's
debugging message, not the real problem. And probably it's unrelated
to the fail of PPP.

Badness in local_bh_enable at kernel/softirq.c:121
Call Trace:
[<c011df25>] local_bh_enable+0x85/0x90
[<c02315e2>] ppp_async_push+0xa2/0x180
[<c0230efd>] ppp_asynctty_wakeup+0x2d/0x60
[<c0202638>] pty_unthrottle+0x58/0x60
[<c01ff0fd>] check_unthrottle+0x3d/0x40
[<c01ff1a3>] n_tty_flush_buffer+0x13/0x60
[<c0202a47>] pty_flush_buffer+0x67/0x70
[<c01fba41>] do_tty_hangup+0x3f1/0x460

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