2.4.19 crash

Happened again, now with "kernel BUG at buffer.c:510!" message. Everything same as before, except:
(a) kernel was recompiled without high memory option
(b) machine was running but not responding at all (no ping) Seems quite serious to me, any ideas?

--------------------------------------------------------------------------

ksymoops 2.4.4 on i686 2.4.19. Options used
-V (default)
-k /proc/ksyms (default)
-l /proc/modules (default)
-o /lib/modules/2.4.19/ (default)
-m /boot/System.map-2.4.19 (default)

Warning: You did not tell me where to find symbol information. [...]

No modules in ksyms, skipping objects
Warning (read_lsmod): no symbols in lsmod, is /proc/modules a valid lsmod file?

Aug  9 10:11:47 [...] kernel: kernel BUG at buffer.c:510!
Aug  9 10:11:47 [...] kernel: invalid operand: 0000
Aug  9 10:11:47 [...] kernel: CPU:    0
Aug  9 10:11:47 [...] kernel: EIP:    0010:[<c01313ee>]    Not tainted
Using defaults from ksymoops -t elf32-i386 -a i386
Aug  9 10:11:47 [...] kernel: EFLAGS: 00010286
Aug  9 10:11:47 [...] kernel: eax: df5ea969   ebx: 00000002   ecx: d50c0040 
  edx: c02d2794
Aug  9 10:11:47 [...] kernel: esi: d50c0040   edi: 00000001   ebp: d50c0040 
  esp: e5005e68
Aug  9 10:11:47 [...] kernel: ds: 0018   es: 0018   ss: 0018
Aug  9 10:11:47 [...] kernel: Process [...] (pid: 14320, stackpage=e5005000)
Aug  9 10:11:47 [...] kernel: Stack: 00000002 c0131c93 d50c0040 00000002 d757b300 00000000 c0132493 d50c0040
Aug  9 10:11:47 [...] kernel:        d50c0040 00001000 c0131ca9 d50c0040 c01326f6 d50c0040 00001000 00000000
Aug  9 10:11:47 [...] kernel:        00001000 0b2ae000 00000000 d757b300 c0132d32 d757b300 c144fb10 00000000
Aug  9 10:11:47 [...] kernel: Call Trace:    [<c0131c93>] [<c0132493>] [<c0131ca9>] [<c01326f6>] [<c0132d32>]
Aug  9 10:11:47 [...] kernel:   [<c0153045>] [<c01528a0>] [<c01261b8>] [<c011b5dd>] [<c0130175>] [<c011790b>]
Aug  9 10:11:47 [...] kernel:   [<c010878b>]
Aug  9 10:11:48 [...] kernel: Code: 0f 0b fe 01 ba 2f 24 c0 8b 02 85 c0 75 07 89 0a 89 49 24 8b

Trace; c0131c93 <__refile_buffer+53/60>
Trace; c0132493 <__block_prepare_write+103/2e0>
Trace; c0131ca9 <refile_buffer+9/10>
Trace; c01326f6 <__block_commit_write+86/d0>
Trace; c0132d32 <generic_commit_write+32/60>
Trace; c0153045 <ext3_commit_write+135/1c0>
Trace; c01528a0 <ext3_get_block+0/60>
Trace; c01261b8 <generic_file_write+4e8/6e0>
Trace; c011b5dd <do_timer+3d/70>
Trace; c0130175 <sys_write+95/f0>
Trace; c011790b <sys_gettimeofday+1b/a0>
Trace; c010878b <system_call+33/38>
Code; c01313ee <__insert_into_lru_list+1e/70>
00000000 <_EIP>:
Code; c01313ee <__insert_into_lru_list+1e/70> <=====
0: 0f 0b ud2a <=====
Code; c01313f0 <__insert_into_lru_list+20/70>
2: fe 01 incb (%ecx)
Code; c01313f2 <__insert_into_lru_list+22/70>
4: ba 2f 24 c0 8b mov $0x8bc0242f,%edx
Code; c01313f7 <__insert_into_lru_list+27/70>
9: 02 85 c0 75 07 89 add 0x890775c0(%ebp),%al
Code; c01313fd <__insert_into_lru_list+2d/70>
f: 0a 89 49 24 8b 00 or 0x8b2449(%ecx),%cl

Aug  9 10:11:48 [...] kernel:  <1>Unable to handle kernel paging request at virtual address 546a53b8

2 warnings issued. Results may not be reliable.

Looks very much like random memory corruption. Could be many things. Does the box pass memtest86 ?

It just passed memtest-2.93.1 (I don't have physical access to machine to run standalone test). BIOS memcheck also runs ok. It usually crashes after 1-5 days, in the meantime all programs run perfectly.

---------------------------------------------------- memtest.log:

Testing 469684224 bytes at 0x42136000 (4088 bytes lost to page alignment).

Run 1:

  Test  1:         Stuck Address:  Setting...Passed.
  Test  2:          Random value:  Setting...Testing...Passed.
  Test  3:        XOR comparison:  Setting...Testing...Passed.
  Test  4:        SUB comparison:  Setting...Testing...Passed.
  Test  5:        MUL comparison:  Setting...Testing...Passed.
  Test  6:        DIV comparison:  Setting...Testing...Passed.
  Test  7:         OR comparison:  Setting...Testing...Passed.
  Test  8:        AND comparison:  Setting...Testing...Passed.
  Test  9:  Sequential Increment:  Setting...Testing...Passed.
  Test 10:            Solid Bits:  Setting...Passed.
  Test 11:      Block Sequential:  Setting...Passed.
  Test 12:          Checkerboard:  Setting...Passed.
  Test 13:            Bit Spread:  Setting...Passed.
  Test 14:              Bit Flip:  Setting...Passed.
  Test 15:          Walking Ones:  Setting...Passed.
  Test 16:        Walking Zeroes:  Setting...Passed.

Run 1 completed in 1476 seconds (0 tests showed errors).
munlock'ed memory.
1 runs completed. 0 errors detected. Total runtime: 1476 seconds.