[patch 056/166] mm/memory_hotplug.c: simplify calculation of number of pages in __remove_pages()

Andrew Morton
2020-04-07T03:06:56Z

From: David Hildenbrand <david@redhat.com>
Subject: mm/memory_hotplug.c: simplify calculation of number of pages in __remove_pages()

In commit 52fb87c81f11 ("mm/memory_hotplug: cleanup __remove_pages()"), we
cleaned up __remove_pages(), and introduced a shorter variant to calculate
the number of pages to the next section boundary.

Turns out we can make this calculation easier to read. We always want to
have the number of pages (> 0) to the next section boundary, starting from
the current pfn.

We'll clean up __remove_pages() in a follow-up patch and directly make use
of this computation.

Link: http://lkml.kernel.org/r/20200228095819.10750-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Suggested-by: Segher Boessenkool <segher@kernel.crashing.org>
Reviewed-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

mm/memory_hotplug.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/mm/memory_hotplug.c~mm-memory_hotplug-simplify-calculation-of-number-of-pages-in-__remove_pages
+++ a/mm/memory_hotplug.c
@@ -534,7 +534,8 @@ void __remove_pages(unsigned long pfn, u
for (; pfn < end_pfn; pfn += cur_nr_pages) {
cond_resched();
/* Select all remaining pages up to the next section boundary */
- cur_nr_pages = min(end_pfn - pfn, -(pfn | PAGE_SECTION_MASK));
+ cur_nr_pages = min(end_pfn - pfn,
+ SECTION_ALIGN_UP(pfn + 1) - pfn);
__remove_section(pfn, cur_nr_pages, map_offset, altmap);
map_offset = 0;
}
_