Re: 4.0.0-rc4: panic in free_block

From: David Miller
Date: Sun Mar 22 2015 - 22:00:35 EST

From: David Ahern <david.ahern@xxxxxxxxxx>
Date: Sun, 22 Mar 2015 18:03:30 -0600

> On 3/22/15 5:54 PM, David Miller wrote:
>>> I just put it on 4.0.0-rc4 and ditto -- problem goes away, so it
>>> clearly suggests the memcpy or memmove are the root cause.
>> Thanks, didn't notice that.
>> So, something is amuck.
> to continue to refine the problem ... I modified only the memmove
> lines (not the memcpy) and it works fine. So its the memmove.
> I'm sure this will get whitespaced damaged on the copy and paste but
> to be clear this is the patch I am currently running and system is
> stable. On Friday it failed on every single; with this patch I have
> allyesconfig builds with -j 128 in a loop (clean in between) and
> nothing -- no panics.

Can you just try calling memcpy(), that should work because
I think we agree that if the memcpy() implementation copies
from low to high it should work.

I wonder if the triggering factor is configuring for a high
number of cpus. I always have NR_CPUS=128 since that's the
largest machine I have. I'll give NR_CPUS=1024 a spin.

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