Subject: Re: [powerpc] Next tree Nov 2 : kernel BUG at mm/mmap.c:2135!

From: David Gibson <[email-masked]>
Date: Thu, 5 Nov 2009 11:16:50 +1100

On Wed, Nov 04, 2009 at 06:08:44PM +0530, Sachin Sant wrote:
> Sachin Sant wrote:
> >Today's next tree failed to boot on a POWER 6 box with :
> >
> >------------[ cut here ]------------
> >kernel BUG at mm/mmap.c:2135!
> >Oops: Exception in kernel mode, sig: 5 [#2]
> >SMP NR_CPUS=1024 NUMA pSeries
> Problem exists with today's next as well.
> 
> Likely cause for this problem seems to the following commit.
> If i revert this patch the machine boots fine.
> 
> commit a0668cdc154e54bf0c85182e0535eea237d53146
> powerpc/mm: Cleanup management of kmem_caches for pagetables

Ugh.  Ok, it's not at all obvious how my patch could cause this bug.
Can you send your .config?

> >Modules linked in: ibmvscsic scsi_transport_srp scsi_tgt scsi_mod
> >NIP: c00000000014e30c LR: c00000000014e2f8 CTR: c00000000014db88
> >REGS: c0000000db703620 TRAP: 0700   Tainted: G      D
> >(2.6.32-rc5-autotest-next-20091102)
> >MSR: 8000000000029032 <EE,ME,CE,IR,DR>  CR: 24022442  XER: 2000000c
> >TASK = c0000000db7f6fe0[76] 'init' THREAD: c0000000db700000 CPU: 1
> >GPR00: 0000000000000001 c0000000db7038a0 c000000000b19900
> >0000000000000000
> >GPR04: c0000000db406a40 000000000000000c c0000000fe10c370
> >c000000000bb2800
> >GPR08: 000000000000db40 0000000000000000 c0000000dfdc0e00
> >000000000000000c
> >GPR12: 0000000044022442 c000000000bb2800 00000000ffffffff
> >ffffffffffffffff
> >GPR16: 0000000008430000 00000000003c0000 c0000000db703ea0
> >c0000000db569108
> >GPR20: c0000000db568908 0000000000000000 c0000000db703d60
> >0000000000000000
> >GPR24: 0000000000000001 0000000000040100 c0000000fe503580
> >c0000000db1ac180
> >GPR28: 0000000000000000 c000000000f812d0 c000000000a84f00
> >0000000000000000
> >NIP [c00000000014e30c] .exit_mmap+0x190/0x1b8
> >LR [c00000000014e2f8] .exit_mmap+0x17c/0x1b8
> >Call Trace:
> >[c0000000db7038a0] [c00000000014e2f8] .exit_mmap+0x17c/0x1b8 (unreliable)
> >[c0000000db703950] [c0000000000916cc] .mmput+0x54/0x164
> >[c0000000db7039e0] [c0000000000968d8] .exit_mm+0x17c/0x1a0
> >[c0000000db703a90] [c000000000098cb8] .do_exit+0x248/0x784
> >[c0000000db703b70] [c0000000000992a8] .do_group_exit+0xb4/0xe8
> >[c0000000db703c00] [c0000000000aca2c] .get_signal_to_deliver+0x3ec/0x478
> >[c0000000db703cf0] [c0000000000134ac] .do_signal+0x6c/0x31c
> >[c0000000db703e30] [c000000000008b7c] do_work+0x24/0x28
> >Instruction dump:
> >7c8407b4 387d0018 4800ab11 60000000 939d0008 7fe3fb78 4bfffdbd 7c7f1b79
> >4082fff4 e81b00e8 3120ffff 7c090110 <0b000000> 382100b0 e8010010 eb61ffd8
> >---[ end trace ec052ac77a8e7cb4 ]---
> >Fixing recursive fault but reboot is needed!
> >
> >mm/mmap.c:2135 corresponds to :
> >
> >BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
> >
> 

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson