[PATCH] lmb: remove overlapping region with next range

[Kumar, Udit]

Hi Mark/Tom

On 9/25/2023 9:01 PM, Tom Rini wrote:
> On Mon, Sep 25, 2023 at 05:27:26PM +0200, Mark Kettenis wrote:
>>> Date: Mon, 25 Sep 2023 11:21:26 -0400
>>> From: Tom Rini <trini at konsulko.com>
>>>
>>> On Sun, Sep 24, 2023 at 04:48:32PM +0530, Udit Kumar wrote:
>>>
>>>> In case of new memory range to be added is coalesced
>>>> with any already added non last lmb region.
>>>>
>>>> And there is possibility that, then region in which new memory
>>>> range added is not adjacent to next region. But have some
>>>> sections are overlapping.
>>>>
>>>> So along with adjacency check with next lmb region,
>>>> check for overlap should be done.
>>>>
>>>> In case overlap  is found, adjust and merge these two lmb
>>>> region into one.
>>>>
>>>> Reported-by: Suman Anna <s-anna at ti.com>
>>>> Signed-off-by: Udit Kumar <u-kumar1 at ti.com>
>>> This is good!  I wonder if this addresses the issue that has caused
>>> other platforms to need to set CONFIG_LMB_MAX_REGIONS=64 and I'm
>>> wondering if any of the other maintainers I've cc'd here can drop back
>>> to the default number of regions and then re-test their failure case?
>>> Thanks!
>> Hi Tom,
>>
>> For the Apple M1 systems I don't think it makes sense to reduce the
>> number of regions.  These systems don't have TPL or SPL, have plenty
>> of memory (at least 8GB) and are really fast.  And we anticipate that
>> the number of memory regions will only grow in the future.
> This partly gets at what I see as part of the problem.  It's been
> unclear to me if it's reasonable to just bump the default to 64 for
> aarch64 (and riscv?) because the problem is that 16 is truly too small,
> or given what we're doing we still don't need a ton of LMB regions as at
> the end of the day things should be coalesced in to just a few and it's
> been an underlying bug in an area everyone assumed wasn't buggy.

Did we observed overlapped memory regions added in lmb region ?

which leads to increase in default number of regions.