Re: mem= causes oops (was Re: BIOS causes (exposes?) modprobe (load_module) kernel oops)

["Randy.Dunlap" <rdunlap@xenotime.net>]

On Fri, 24 Mar 2006 09:36:13 -0800 John Z. Bohach wrote:

> On Wednesday 22 March 2006 21:42, Randy.Dunlap wrote:
> > > So it seems that the page fault handler is somehow affected by something
> > > that the BIOS has/has not done, long after the system has booted and been
> > > running, with many page faults under its belt...now I've seen it all...or
> > > not.
> >
> > Sounds like we need to see complete boot logs from both BIOSen boots.
> > Can you do that?
> >
> > I'm just guessing that the memory maps are different, but who knows.
> 
> I got something...
> 
> Here's the symbolic dump.  I've gotten it to break on the BIOS it
> did work on, by adding 512 MB RAM and bringing the total RAM to 1GB.
> In fact, it now breaks during boot-up, and doesn't even give me a chance
> to modprobe anything.  However, the cmdline is what makes it break/work:
> 
> Here it is:
> 
> fails with cmdline:
> 
> Kernel command line: ro root=/dev/sda1 rootdelay=10 mem=0x200M console=ttyS0,115200n8
> 
> works with:
> 
> Kernel command line: ro root=/dev/sda1 rootdelay=10 console=ttyS0,115200n8
> 
> Note the "mem=" being the differentiator!

OK, that is memory map difference.

Can you test a more recent kernel to see if it has the same problem?
(like 2.6.16 or 2.6.16-git9)


> So I guess BIOS is off the hook.  Here's a more interesting dump of the new failing
> case (with 1 GB RAM, and mem=0x200M on command line).  BTW, note that
> mem=0x200M works fine as long as there's only 512 MB in the system.
> 
> (And also note that the kernel was built without ACPI (or APM) support).
> 
> INIT: version 2.85 booting
> INIT: Entering runlevel: 3
> Starting system log daemon...
> [   39.333210] Unable to handle kernel paging request at virtual address b7c4e000
> [   39.340642]  printing eip:
> [   39.343414] c013213c
> [   39.345653] *pde = 017eb067
> [   39.348516] *pte = 00000000
> [   39.351379] Oops: 0002 [#1]
> [   39.354239] SMP DEBUG_PAGEALLOC
> [   39.357476] Modules linked in:
> [   39.360615] CPU:    0
> [   39.360616] EIP:    0060:[<c013213c>]    Not tainted VLI
> [   39.360618] EFLAGS: 00010006   (2.6.14.2) 
> [   39.373302] EIP is at free_block+0x41/0xbc
> [   39.377501] eax: c1508d40   ebx: dffb6000   ecx: dffb6b80   edx: b7c4e000
> [   39.384458] esi: c1508d40   edi: 00000000   ebp: c1505280   esp: c1567ef4
> [   39.391413] ds: 007b   es: 007b   ss: 0068
> [   39.395622] Process events/0 (pid: 4, threadinfo=c1566000 task=c151fa30)
> [   39.402309] Stack: c150aa14 00000003 c150aa00 c1505280 c0132963 c1505280 c150aa14 00000003 
> [   39.410930]        00000000 00000000 c1508368 c1508d10 c1508d40 c1505280 c0132a0d c1505280 
> [   39.419568]        c150aa00 00000000 00000000 00000002 c15052dc 00000246 c14063e0 c14063e4 
> [   39.428186] Call Trace:
> [   39.430878]  [<c0132963>] drain_array_locked+0x61/0x8c
> [   39.436161]  [<c0132a0d>] cache_reap+0x7f/0x18f
> [   39.440823]  [<c011f86a>] worker_thread+0x16f/0x1dd
> [   39.445843]  [<c013298e>] cache_reap+0x0/0x18f
> [   39.450420]  [<c0110299>] default_wake_function+0x0/0x12
> [   39.455879]  [<c0110299>] default_wake_function+0x0/0x12
> [   39.461338]  [<c011f6fb>] worker_thread+0x0/0x1dd
> [   39.466173]  [<c0122d23>] kthread+0x7c/0xa6
> [   39.470472]  [<c0122ca7>] kthread+0x0/0xa6
> [   39.474681]  [<c0100ea5>] kernel_thread_helper+0x5/0xb
> [   39.479967] Code: 24 18 8b 15 50 ec 31 c0 8b 0c b8 8d 81 00 00 00 40 c1 e8 0c c1 e0 05 8b 5c 02 1c 8b 44 24 20 8b 53  
> [   39.499780]  
> 
> [42949372.960000] Linux version 2.6.14.2 (root@zeus) (gcc version 3.3.4) #1 SMP Fri Mar 24 08:27:33 PST 2006
> [42949372.960000] BIOS-provided physical RAM map:
> [42949372.960000]  BIOS-e820: 0000000000000000 - 000000000009fc00 (usable)
> [42949372.960000]  BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved)
> [42949372.960000]  BIOS-e820: 00000000000e0000 - 0000000000100000 (reserved)
> [42949372.960000]  BIOS-e820: 0000000000100000 - 000000003fe30000 (usable)
> [42949372.960000]  BIOS-e820: 000000003fe30000 - 000000003fe40000 (ACPI data)
> [42949372.960000]  BIOS-e820: 000000003fe40000 - 000000003ff00000 (ACPI NVS)
> [42949372.960000]  BIOS-e820: 000000003ff00000 - 0000000040000000 (reserved)
> [42949372.960000]  BIOS-e820: 00000000fec00000 - 00000000fec01000 (reserved)
> [42949372.960000]  BIOS-e820: 00000000fee00000 - 00000000fee01000 (reserved)
> [42949372.960000] user-defined physical RAM map:
> [42949372.960000]  user: 0000000000000000 - 000000000009fc00 (usable)
> [42949372.960000]  user: 000000000009fc00 - 00000000000a0000 (reserved)
> [42949372.960000]  user: 00000000000e0000 - 0000000000100000 (reserved)
> [42949372.960000]  user: 0000000000100000 - 0000000020000000 (usable)
> [42949372.960000] 512MB LOWMEM available.
> [42949372.960000] found SMP MP-table at 000ff780
> ...
> 
> Thanks for taking a look...

---
~Randy