mm/page_alloc: remove unnecessary check in break_down_buddy_pages

mm/page_alloc: remove unnecessary check in break_down_buddy_pages

Patch series "Two minor cleanups to break_down_buddy_pages", v2.

Two minor cleanups to break_down_buddy_pages.

This patch (of 2):

1. We always have target in range started with next_page and full free
   range started with current_buddy.

2. The last split range size is 1 << low and low should be >= 0, then
   size >= 1.  So page + size != page is always true (because size > 0).
   As summary, current_page will not equal to target page.

Link: https://lkml.kernel.org/r/20230927103514.98281-1-shikemeng@huaweicloud.com
Link: https://lkml.kernel.org/r/20230927103514.98281-2-shikemeng@huaweicloud.com
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>