Re: 4.0.0-rc4: panic in free_block

[David Miller <davem@davemloft.net>]

From: David Ahern <david.ahern@oracle.com>
Date: Sun, 22 Mar 2015 17:35:49 -0600

> I don't know if you caught Bob's message; he has a hack to bypass
> memcpy and memmove in mm/slab.c use a for loop to move entries. With
> the hack he is not seeing the problem.
> 
> This is the hack:
> 
> +static void move_entries(void *dest, void *src, int nr)
> +{
> +       unsigned long *dp = dest;
> +       unsigned long *sp = src;
> +
> +       for (; nr; nr--, dp++, sp++)
> +               *dp = *sp;
> +}
> +
> 
> and then replace the mempy and memmove calls in transfer_objects,
> cache_flusharray and drain_array to use move_entries.
> 
> 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.

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