Re: [PATCH v5 4/5] mm/sparse: add new sparse_init_nid() and sparse_init()

[Oscar Salvador]

On Thu, Jul 12, 2018 at 04:37:29PM -0400, Pavel Tatashin wrote:
> sparse_init() requires to temporary allocate two large buffers:
> usemap_map and map_map. Baoquan He has identified that these buffers are so
> large that Linux is not bootable on small memory machines, such as a kdump
> boot. The buffers are especially large when CONFIG_X86_5LEVEL is set, as
> they are scaled to the maximum physical memory size.
> 
> Baoquan provided a fix, which reduces these sizes of these buffers, but it
> is much better to get rid of them entirely.
> 
> Add a new way to initialize sparse memory: sparse_init_nid(), which only
> operates within one memory node, and thus allocates memory either in large
> contiguous block or allocates section by section. This eliminates the need
> for use of temporary buffers.
> 
> For simplified bisecting and review temporarly call sparse_init()
> new_sparse_init(), the new interface is going to be enabled as well as old
> code removed in the next patch.
> 
> Signed-off-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>

Looks good to me, and it will make the code much shorter/easier.

Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>

Thanks
-- 
Oscar Salvador
SUSE L3