On October 5, 2018 6:25:38 AM GMT+03:00, Benjamin Herrenschmidt [off-list ref] wrote:

On Fri, 2018-10-05 at 00:07 +0300, Mike Rapoport wrote:

quoted

When a memblock allocation APIs are called with align = 0, the

alignment is

quoted

implicitly set to SMP_CACHE_BYTES.

Replace all such uses of memblock APIs with the 'align' parameter

explicitly

quoted

set to SMP_CACHE_BYTES and stop implicit alignment assignment in the
memblock internal allocation functions.

For the case when memblock APIs are used via helper functions, e.g.

like

quoted

iommu_arena_new_node() in Alpha, the helper functions were detected

with

quoted

Coccinelle's help and then manually examined and updated where

appropriate.

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The direct memblock APIs users were updated using the semantic patch

below:

What is the purpose of this ? It sounds rather counter-intuitive...

Why?
I think it actually more intuitive to explicitly set alignment to SMP_CACHE_BYTES rather than use align = 0 because deeply inside allocator it will be implicitly reset to SMP_CACHE_BYTES...

Ben.

-- 
Sincerely yours,
Mike.