[bug report v4.8] fs/locks.c: kernel oops during posix lock stress test

[Ming Lei]

Hi Will,

On Mon, Nov 28, 2016 at 6:52 PM, Will Deacon <will.deacon at arm.com> wrote:
> Hi Ming,
>
> On Mon, Nov 28, 2016 at 11:10:14AM +0800, Ming Lei wrote:
>> When I run stress-ng via the following steps on one ARM64 dual
>> socket system(Cavium Thunder), the kernel oops[1] can often be
>> triggered after running the stress test for several hours(sometimes
>> it may take longer):
>>
>> - git clone git://kernel.ubuntu.com/cking/stress-ng.git
>> - apply the attachment patch which just makes the posix file
>> lock stress test more aggressive
>> - run the test via '~/git/stress-ng$./stress-ng --lockf 128 --aggressive'
>>
>>
>> From the oops log, looks one garbage file_lock node is got
>> from the linked list of 'ctx->flc_posix' when the issue happens.
>>
>> BTW, the issue isn't observed on single socket Cavium Thunder yet,
>> and the same issue can be seen on Ubuntu Xenial(v4.4 based kernel)
>> too.
>
> I've seen issues with the LSE atomics on the Thunder platform -- can you
> try disabling those (CONFIG_ARM64_LSE_ATOMICS) and see if the problem
> persists, please?
>

Ubuntu Xenial doesn't enable CONFIG_ARM64_LSE_ATOMICS, which
is disabled in my v4.8 kernel config too, please see that in the attachement.


Thanks,
Ming
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