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

From: lkml-031128
Date: Sat Nov 29 2003 - 12:03:18 EST

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In reply to: OGAWA Hirofumi: "Re: PROBLEM: 2.6test11 kernel panic on "head -1 /proc/net/tcp""
Next in thread: Thomas Cataldo: "Re: PROBLEM: 2.6test11 kernel panic on "head -1 /proc/net/tcp""
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OGAWA Hirofumi wrote:

lkml-031128@xxxxxxxxxxxxxxxxxx writes:

"bad: scheduling while atomic!
Call Trace:
schedule+0x55d/0x570

Does this patch fix this problem?

diff -puN net/ipv4/tcp_ipv4.c~tcp_seq-oops-fix net/ipv4/tcp_ipv4.c
--- linux-2.6.0-test11/net/ipv4/tcp_ipv4.c~tcp_seq-oops-fix 2003-11-29 00:52:15.000000000 +0900
+++ linux-2.6.0-test11-hirofumi/net/ipv4/tcp_ipv4.c 2003-11-29 00:52:28.000000000 +0900
@@ -2356,6 +2356,7 @@ static void *tcp_get_idx(struct seq_file
static void *tcp_seq_start(struct seq_file *seq, loff_t *pos)
{
struct tcp_iter_state* st = seq->private;
+ st->state = TCP_SEQ_STATE_LISTENING;
st->num = 0;
return *pos ? tcp_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
}

_

Partially. It seems to trigger ppp failure later.

What I do to test this:

1. Compiled a pre-emptive kernel with nothing different in the config
and the code except that I added your patch.

2. Boot to single user mode as before.

3. "cat /proc/net/tcp" runs fine.

4. "head -1 /proc/net/tcp" runs fine (it used to freeze with an oops, as
described in my original message).

5. I logout from single user mode and let the system boot to multi-user.

This gives me tons of messages like the following:

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
[<c01fcfbc>] release_dev+0x62c/0x660
[<c013dfab>] zap_pmd_range+0x4b/0x70
[<c013e013>] unmap_page_range+0x43/0x70
[<c01622a2>] dput+0x22/0x210
[<c01fd38a>] tty_release+0x2a/0x60
[<c014ccf8>] __fput+0x108/0x120
[<c014b359>] filp_close+0x59/0x90
[<c011b874>] put_files_struct+0x54/0xc0
[<c011c47d>] do_exit+0x15d/0x3e0
[<c011c79a>] do_group_exit+0x3a/0xb0
[<c01091b7>] syscall_call+0x7/0xb

PPP fails. Re-run "pon adsl-provider" or "/etc/init.d/ppp start" fails.
What I get on such attempts are messages in /var/log/messages
like:

Nov 29 18:48:57 picton kernel: Badness in local_bh_enable at kernel/softirq.c:121
Nov 29 18:48:57 picton kernel: Call Trace:
Nov 29 18:48:57 picton kernel: [local_bh_enable+133/144] local_bh_enable+0x85/0x90
Nov 29 18:48:57 picton kernel: [ppp_async_push+162/384] ppp_async_push+0xa2/0x180
Nov 29 18:48:57 picton kernel: [ppp_asynctty_wakeup+45/96] ppp_asynctty_wakeup+0x2d/0x60
Nov 29 18:48:57 picton kernel: [pty_unthrottle+88/96] pty_unthrottle+0x58/0x60
Nov 29 18:48:57 picton kernel: [check_unthrottle+61/64] check_unthrottle+0x3d/0x40
Nov 29 18:48:57 picton kernel: [n_tty_flush_buffer+19/96] n_tty_flush_buffer+0x13/0x60
Nov 29 18:48:57 picton kernel: [pty_flush_buffer+103/112] pty_flush_buffer+0x67/0x70
Nov 29 18:48:57 picton kernel: [do_tty_hangup+1009/1120] do_tty_hangup+0x3f1/0x460
Nov 29 18:48:57 picton kernel: [release_dev+1580/1632] release_dev+0x62c/0x660
Nov 29 18:48:57 picton kernel: [zap_pmd_range+75/112] zap_pmd_range+0x4b/0x70
Nov 29 18:48:57 picton kernel: [unmap_page_range+67/112] unmap_page_range+0x43/0x70
Nov 29 18:48:57 picton kernel: [dput+34/528] dput+0x22/0x210
Nov 29 18:48:57 picton kernel: [tty_release+42/96] tty_release+0x2a/0x60
Nov 29 18:48:57 picton kernel: [__fput+264/288] __fput+0x108/0x120
Nov 29 18:48:57 picton kernel: [filp_close+89/144] filp_close+0x59/0x90
Nov 29 18:48:57 picton kernel: [put_files_struct+84/192] put_files_struct+0x54/0xc0
Nov 29 18:48:57 picton kernel: [do_exit+349/992] do_exit+0x15d/0x3e0
Nov 29 18:48:57 picton kernel: [do_group_exit+58/176] do_group_exit+0x3a/0xb0
Nov 29 18:48:57 picton kernel: [syscall_call+7/11] syscall_call+0x7/0xb
Nov 29 18:48:57 picton kernel:
Nov 29 18:48:57 picton pppd[32717]: Modem hangup
Nov 29 18:48:57 picton pppd[32717]: Connection terminated.
Nov 29 18:48:57 picton pppd[32717]: Exit.

Ksymoops doesn't seem to add much useful data, here is what I get
from it:

Trace; c011df25 <local_bh_enable+85/90>
Trace; c02315e2 <ppp_async_push+a2/180>
Trace; c0230efd <ppp_asynctty_wakeup+2d/60>
Trace; c0202638 <pty_unthrottle+58/60>
Trace; c01ff0fd <check_unthrottle+3d/40>
Trace; c01ff1a3 <n_tty_flush_buffer+13/60>
Trace; c0202a47 <pty_flush_buffer+67/70>
Trace; c01fba41 <do_tty_hangup+3f1/460>
Trace; c01fcfbc <release_dev+62c/660>
Trace; c013dfab <zap_pmd_range+4b/70>
Trace; c013e013 <unmap_page_range+43/70>
Trace; c01622a2 <dput+22/210>
Trace; c01fd38a <tty_release+2a/60>
Trace; c014ccf8 <__fput+108/120>
Trace; c014b359 <filp_close+59/90>
Trace; c011b874 <put_files_struct+54/c0>
Trace; c011c47d <do_exit+15d/3e0>
Trace; c011c79a <do_group_exit+3a/b0>
Trace; c01091b7 <syscall_call+7/b>

If I avoid doing the "head -1 /proc/net/tcp" in single user then PPP
works.

Thanks,

--Amos

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Next message: Larry McVoy: "Re: Too soon for stable release?"
Previous message: Jeff Garzik: "Re: Silicon Image 3112A SATA trouble"
In reply to: OGAWA Hirofumi: "Re: PROBLEM: 2.6test11 kernel panic on "head -1 /proc/net/tcp""
Next in thread: Thomas Cataldo: "Re: PROBLEM: 2.6test11 kernel panic on "head -1 /proc/net/tcp""
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