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From: Michael Ellerman <mpe@ellerman•id.au>
To: vrbagal1 <vrbagal1@linux•vnet.ibm.com>,
	Nicholas Piggin <npiggin@gmail•com>
Cc: linux-fsdevel@vger•kernel.org,
	sachinp <sachinp@linux•vnet.ibm.com>,
	linuxppc-dev <linuxppc-dev@lists•ozlabs.org>,
	Linuxppc-dev
	<linuxppc-dev-bounces+vrbagal1=linux.vnet.ibm.com@lists•ozlabs.org>
Subject: Re: [powerpc/powervm]Oops: Kernel access of bad area, sig: 11 [#1] while running stress-ng
Date: Tue, 10 Jul 2018 23:42:00 +1000	[thread overview]
Message-ID: <877em3b42f.fsf@concordia.ellerman.id.au> (raw)
In-Reply-To: <920d9bc6a2c3449700dec191c271bdff@linux.vnet.ibm.com>

vrbagal1 <vrbagal1@linux•vnet.ibm.com> writes:

> On 2018-07-10 13:37, Nicholas Piggin wrote:
>> On Tue, 10 Jul 2018 11:58:40 +0530
>> vrbagal1 <vrbagal1@linux•vnet.ibm.com> wrote:
>> 
>>> Hi,
>>> 
>>> Observing kernel oops on Power9(ZZ) box, running on PowerVM, while
>>> running stress-ng.
>>> 
>>> 
>>> Kernel: 4.18.0-rc4
>>> Machine: Power9 ZZ (PowerVM)
>>> Test: Stress-ng
>>> 
>>> Attached is .config file
>>> 
>>> Traces:
>>> 
>>>   [12251.245209] Oops: Kernel access of bad area, sig: 11 [#1]
>> 
>> Can you post the lines above this? Otherwise we don't know what address
>> it tried to access (without decoding the instructions and 
>> reconstructing
>> it from registers at least, which the XFS devs wouldn't be inclined to
>> do).
>> 
>
> ah my bad.
>
>   [12251.245179] Unable to handle kernel paging request for data at address 0x6000000060000000
>   [12251.245199] Faulting instruction address: 0xc000000000319e2c

Which matches the regs & disassembly:

r4 = 6000000060000000 
r9 = 0
ldx     r9,r4,r9	<- pop

So object was 0x6000000060000000.

That looks like two nops, ie. we got some code?

And there's only one caller of prefetch_freepointer() in slab_alloc_node():

	prefetch_freepointer(s, next_object);


So slab corruption is looking likely.

Do you have slub_debug=FZP on the kernel command line?

cheers

  reply	other threads:[~2018-07-10 13:42 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-10  6:28 [powerpc/powervm]Oops: Kernel access of bad area, sig: 11 [#1] while running stress-ng vrbagal1
2018-07-10  8:07 ` Nicholas Piggin
2018-07-10 10:11   ` vrbagal1
2018-07-10 13:42     ` Michael Ellerman [this message]
2018-07-19  6:17       ` vrbagal1
2018-07-19 13:33         ` Brian Foster
2018-07-20  6:02           ` vrbagal1

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