Messages in this thread |  | | Date | Thu, 07 Dec 2000 18:16:08 -0800 | From | Joseph Cheek <> | Subject | Re: kernel BUG at buffer.c:827 in test12-pre6 and 7 |
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hi,
comments below.
Linus Torvalds wrote:
> In article <3A30125D.5F71110D@cheek.com>, > Joseph Cheek <joseph@cheek.com> wrote: > >copying files off a loopback-mounted vfat filesystem exposes this bug. > >test11 worked fine. > > It's not a new bug - it's an old bug that apparently is uncovered by a > new stricter test. > > Apparently loopback unlocks an already unlocked page - which has always > been a serious offense, but has never been detected before. > > test12-pre6+ detects it, and thus the BUG(). > > Your stack trace isn't symbolic (see Documentation/oops-tracing.txt), so > it's impossible to debug, but it's already interesting information to > see that it seems to be either loopback of vfat. > > Can you test some more? In particular, I'd love to hear if this happens > with vfat even without loopback, or with loopback even without vfat > (make an ext2 filesystem or similar instead). That woul dnarrow down the > bug further.
this happens on loopbacked ext2, and not on regular vfat. so it appears that the culprit is loopback. i got ksymoops working, here are the traces from the vfat-over-loopback [first] and the ext2-over-loopback [second].
again, these are copied by hand, so i give it a 1% chance of mistranscription.
ksymoops 2.3.5 on i686 2.4.0. Options used -V (default) -k /proc/ksyms (default) -l /proc/modules (default) -o /lib/modules/2.4.0/ (default) -m /usr/src/linux/System.map (default)
Warning: You did not tell me where to find symbol information. I will assume that the log matches the kernel and modules that are running right now and I'll use the default options above for symbol resolution. If the current kernel and/or modules do not match the log, you can get more accurate output by telling me the kernel version and where to find map, modules, ksyms etc. ksymoops -h explains the options.
kernel BUG at buffer.c:827! invalid operand: 0000 CPU: 0 EIP: 0010:[<c013660c>] Using defaults from ksymoops -t elf32-i386 -a i386 EFLAGS: 00010082 eax: 0000001c ebx: c1d8fc60 ecx: 00000000 edx: 00000001 esi: c10658e4 edi: 00000002 ebp: c1d8fca8 esp: c1793dc0 ds: 0018 es: 0018 ss: 0018 Process cp (pid 762, stackpage=c1793000) Stack: c01fe484 c01fe95a 0000033b c1d8fc60 c1cef420 00000001 00000001 c01610e1 c1d8fc60 00000001 c1cef420 00000000 c1cef420 c02c8ed8 c88df91c c1cef420 00000001 c88e0986 00000007 00000000 00000001 c02c8ed8 c02c8ee8 c4f18800 Call Trace: [<c01fe484>] [<c01fe95a>] [<c0130703>] [<c8895de3>] [<c88df91c>] [<c8894494>] [<c0160d2f>] [<c0160ead>] [<c0161011>] [<c0137a49>] [<c0130703>] [<c8895de3>] [<c8894494>] [<c01284d3>] [<c012887b>] [c0128720>] [<c889448d>] [<c01349a7>] [c010b56b>] Code: 0f 0b 83 c4 0c 8d 5e 28 8d 46 2c 39 46 2c 74 24 b9 01 00 00
>>EIP; c013660c <end_buffer_io_async+e0/11c> <===== Trace; c01fe484 <tvecs+4fc0/13968> Trace; c01fe95a <tvecs+5496/13968> Trace; c0130703 <__alloc_pages+df/2d4> Trace; c8895de3 <[fat]fat_readpage+f/14> Trace; c88df91c <[cdrom]cdrom_read_mech_status+c/4c> Trace; c8894494 <[fat]fat_get_block+0/e4> Trace; c0160d2f <__make_request+5cb/648> Trace; c0160ead <generic_make_request+101/110> Trace; c0161011 <ll_rw_block+155/1c4> Trace; c0137a49 <block_read_full_page+1fd/2a8> Trace; c0130703 <__alloc_pages+df/2d4> Trace; c8895de3 <[fat]fat_readpage+f/14> Trace; c8894494 <[fat]fat_get_block+0/e4> Trace; c01284d3 <do_generic_file_read+337/584> Trace; c012887b <generic_file_read+5b/74> Trace; c889448d <[fat]fat_file_read+2d/34> Trace; c01349a7 <sys_read+8f/c4> Code; c013660c <end_buffer_io_async+e0/11c> 0000000000000000 <_EIP>: Code; c013660c <end_buffer_io_async+e0/11c> <===== 0: 0f 0b ud2a <===== Code; c013660e <end_buffer_io_async+e2/11c> 2: 83 c4 0c add $0xc,%esp Code; c0136611 <end_buffer_io_async+e5/11c> 5: 8d 5e 28 lea 0x28(%esi),%ebx Code; c0136614 <end_buffer_io_async+e8/11c> 8: 8d 46 2c lea 0x2c(%esi),%eax Code; c0136617 <end_buffer_io_async+eb/11c> b: 39 46 2c cmp %eax,0x2c(%esi) Code; c013661a <end_buffer_io_async+ee/11c> e: 74 24 je 34 <_EIP+0x34> c0136640 <end_buffer_io_async+114/11c> Code; c013661c <end_buffer_io_async+f0/11c> 10: b9 01 00 00 00 mov $0x1,%ecx
1 warning issued. Results may not be reliable.
ksymoops 2.3.5 on i686 2.4.0. Options used -V (default) -k /proc/ksyms (default) -l /proc/modules (default) -o /lib/modules/2.4.0/ (default) -m /usr/src/linux/System.map (default)
Warning: You did not tell me where to find symbol information. I will assume that the log matches the kernel and modules that are running right now and I'll use the default options above for symbol resolution. If the current kernel and/or modules do not match the log, you can get more accurate output by telling me the kernel version and where to find map, modules, ksyms etc. ksymoops -h explains the options.
kernel BUG at buffer.c:827! invalid operand: 0000 CPU: 0 EIP: 0010:[<c013660c>] Using defaults from ksymoops -t elf32-i386 -a i386 EFLAGS: 00010086 eax: 0000001c ebx: c1d212a0 ecx: 00000000 edx: 00000001 esi: c11274bc edi: 00000002 ebp: c1d212e8 esp: c4f1bddc ds: 0018 es: 0018 ss: 0018 Process cp (pid 772, stackpage=c4f1b000) Stack: c01fe484 c01fe95a 0000033b c1d21290 c1983420 00000002 00000001 c01610e1 c1d212a0 00000001 c1983420 00000000 c1983420 c02c8ed8 c88df91c c1983420 00000001 c88e0986 00000007 00000000 00000002 c02c8ed8 c02c8ee8 c4cdf998 Call Trace: [<c01fe484>] [<c01fe95a>] [<c01610e1>] [<c88df91c>] [<c88e0986>] [<c0160d2f>] [<c0160ead>] [<c0161011>] [<c0137a49>] [<c0130703>] [<c0156223>] [<c0155b38>] [<c012887b>] [c0128720>] [<c01349a7>] [c010b56b>] Code: 0f 0b 83 c4 0c 8d 5e 28 8d 46 2c 39 46 2c 74 24 b9 01 00 00
>>EIP; c013660c <end_buffer_io_async+e0/11c> <===== Trace; c01fe484 <tvecs+4fc0/13968> Trace; c01fe95a <tvecs+5496/13968> Trace; c01610e1 <end_that_request_first+61/b8> Trace; c88df91c <[cdrom]cdrom_read_mech_status+c/4c> Trace; c88e0986 <[cdrom]cdrom_read_block+3a/f8> Trace; c0160d2f <__make_request+5cb/648> Trace; c0160ead <generic_make_request+101/110> Trace; c0161011 <ll_rw_block+155/1c4> Trace; c0137a49 <block_read_full_page+1fd/2a8> Trace; c0130703 <__alloc_pages+df/2d4> Trace; c0156223 <ext2_readpage+f/14> Trace; c0155b38 <ext2_get_block+0/4e0> Trace; c012887b <generic_file_read+5b/74> Trace; c01349a7 <sys_read+8f/c4> Code; c013660c <end_buffer_io_async+e0/11c> 0000000000000000 <_EIP>: Code; c013660c <end_buffer_io_async+e0/11c> <===== 0: 0f 0b ud2a <===== Code; c013660e <end_buffer_io_async+e2/11c> 2: 83 c4 0c add $0xc,%esp Code; c0136611 <end_buffer_io_async+e5/11c> 5: 8d 5e 28 lea 0x28(%esi),%ebx Code; c0136614 <end_buffer_io_async+e8/11c> 8: 8d 46 2c lea 0x2c(%esi),%eax Code; c0136617 <end_buffer_io_async+eb/11c> b: 39 46 2c cmp %eax,0x2c(%esi) Code; c013661a <end_buffer_io_async+ee/11c> e: 74 24 je 34 <_EIP+0x34> c0136640 <end_buffer_io_async+114/11c> Code; c013661c <end_buffer_io_async+f0/11c> 10: b9 01 00 00 00 mov $0x1,%ecx
1 warning issued. Results may not be reliable.
-- thanks!
joe
-- Joseph Cheek, Sr Linux Consultant, Linuxcare | http://www.linuxcare.com/ Linuxcare. Support for the Revolution. | joseph@linuxcare.com CTO / Acting PM, Redmond Linux Project | joseph@redmondlinux.org 425 990-1072 vox [1074 fax] 206 679-6838 pcs | joseph@cheek.com
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