[bisected][mismerge?] Re: [microcode] 2.6.23.git pulled this morning oopses loading P4 microcode

[Mike Galbraith <efault@gmx.de>]

On Thu, 2007-10-18 at 06:25 +0200, Mike Galbraith wrote:
> Greetings,
> 
> Freshly pulled tree oopes per $subject.
> 
> [  114.714335] BUG: unable to handle kernel NULL pointer dereference at virtual address 00000031
> [  114.732810] printing eip: c03332ff *pde = 00000000 
> [  114.747614] Oops: 0000 [#1] PREEMPT SMP 
> [  114.761320] Modules linked in: microcode snd_seq edd button battery ac ip6t_REJECT xt_tcpudp ipt_REJECT xt_state iptable_mangle iptable_nat nf_nat iptable_filter ip6table_mangle nf_conntrack_ipv4 nf_conntrack ip_tables ip6table_filter ip6_tables x_tables nls_iso8859_1 nls_cp437 nls_utf8 snd_intel8x0 snd_ac97_codec ac97_bus snd_pcm snd_mpu401 snd_timer snd_mpu401_uart snd_rawmidi prism54 snd_page_alloc snd_seq_device snd soundcore intel_agp agpgart i2c_i801 fan thermal processor
> [  114.781462] CPU:    0
> [  114.781464] EIP:    0060:[<c03332ff>]    Not tainted VLI
> [  114.781468] EFLAGS: 00010293   (2.6.23-smp-git #13)
> [  114.781478] EIP is at misc_register+0x53/0x14f
> [  114.781483] eax: 00000025   ebx: f8bff858   ecx: f8bff900   edx: 00000031
> [  114.781490] esi: 000000b8   edi: f8bff864   ebp: c2e0de88   esp: c2e0de68
> [  114.781496] ds: 007b   es: 007b   fs: 00d8  gs: 0033  ss: 0068
> [  114.781502] Process modprobe (pid: 6115, ti=c2e0d000 task=c2efa070 task.ti=c2e0d000)
> [  114.781508] Stack: c1cb4070 f8bff900 c2e0de88 c014818c f8bff900 f8bff900 f8bff900 00000029 
> [  114.781521]        c2e0de9c f8bac011 c01368e6 ffffffff f8bff900 c2e0dfb0 c0149dfa 00000000 
> [  114.781533]        00000000 00002000 c04d4060 c2e0ded0 c2e0df58 f8be0058 f8be0054 f8bff948 
> [  114.781545] Call Trace:
> [  114.781548]  [<c010514a>] show_trace_log_lvl+0x1a/0x30
> [  114.781558]  [<c0105205>] show_stack_log_lvl+0xa5/0xca
> [  114.781564]  [<c0105426>] show_registers+0x1fc/0x33d
> [  114.781571]  [<c010567d>] die+0x116/0x239
> [  114.781577]  [<c011d008>] do_page_fault+0x2dc/0x5c4
> [  114.781585]  [<c04c0662>] error_code+0x72/0x78
> [  114.781594]  [<f8bac011>] microcode_init+0x11/0xbb [microcode]
> [  114.781604]  [<c0149dfa>] sys_init_module+0xef/0x19bb
> [  114.781612]  [<c01041ba>] syscall_call+0x7/0xb
> [  114.781618]  =======================
> [  114.781621] Code: 0c 0f 18 02 90 81 3d 60 d5 61 c0 60 d5 61 c0 0f 84 fb 00 00 00 8b 33 39 30 75 0d e9 a9 00 00 00 39 30 0f 84 a1 00 00 00 8d 42 f4 <8b> 50 0c 0f 18 02 90 3d 54 d5 61 c0 75 e7 81 fe ff 00 00 00 0f 
> [  114.781677] EIP: [<c03332ff>] misc_register+0x53/0x14f SS:ESP 0068:c2e0de68
> 
> (gdb) list *misc_register+0x53
> 0xc03332ff is in misc_register (drivers/char/misc.c:194).
> 189             int err = 0;
> 190
> 191             INIT_LIST_HEAD(&misc->list);
> 192
> 193             mutex_lock(&misc_mtx);
> 194             list_for_each_entry(c, &misc_list, list) {
> 195                     if (c->minor == misc->minor) {
> 196                             mutex_unlock(&misc_mtx);
> 197                             return -EBUSY;
> 198                     }
> 

The winner of a very long git bisect session:

04c71976500352d02f60616d2b960267d8c5fe24 is first bad commit
commit 04c71976500352d02f60616d2b960267d8c5fe24
Author: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date:   Tue Oct 16 23:27:04 2007 -0700

    unicode diacritics support


Attempting to revert with git:

root@Homer: git revert 04c71976500352d02f60616d2b960267d8c5fe24
Auto-merged drivers/char/keyboard.c
Auto-merged drivers/char/vt_ioctl.c
CONFLICT (delete/modify): drivers/tc/lk201-map.c_shipped deleted in HEAD and modified in 04c7197... unicode diacritics support. Version 04c7197... unicode diacritics support of drivers/tc/lk201-map.c_shipped left in tree.
Automatic revert failed.  After resolving the conflicts,
mark the corrected paths with 'git-add <paths>'
and commit the result.

I reverted it manually in my working tree, ignoring a couple of bogus
rejects and the missing lk201-map.c_shipped which is _created_ in the
git tree by the attempt to revert, and now have a working kernel.  The
oops on microcode driver load is gone, as is the freeze on shutdown when
scripts attempt to set hardware clock, nmi_watchdog firing when I poke
SysRq-T, and the inability to login via serial console reported in
thread:

http://groups.google.com/group/fa.linux.kernel/msg/1b08c2f15894aaf7

	-Mike