block layer bug with 4.4-rc3+

[Ming Lei]

On Wed, Dec 16, 2015 at 11:43 PM, Arnd Bergmann <arnd at arndb.de> wrote:
> On Wednesday 16 December 2015 14:55:43 Andre Przywara wrote:
>> Using the plain multi_v7_defconfig (which doesn't have LPAE and makes me
>> loose half of the RAM on that box) didn't show the bug so far.
>> One of the effects of turning on LPAE is that dma_addr_t and phys_addr_t
>> turn to 64-bit, with long, int and void* still being 32-bit. Can you
>> think of any issues that could be related to that?
>>
>
> Another difference between the platforms is highmem. On Midway,
> almost all of RAM is highmem, which needs a lot of special handling
> that we don't need on platform with less RAM.

Yeah, block bounce can be triggered for highmem generally.

>
> To rule out both of highmem and LPAE, it might be interesting to
> test again on Midway with CONFIG_HIGHMEM and CONFIG_LPAE disabled.
> This will limit the RAM to 768MB, but if the bug still shows up,
> you know it's something else.
>
>         Arnd
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