linux-kernel - [PATCH v1] mm/memory_hotplug: Easier calculation to get pages to next section boundary

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Date:   Wed,  5 Feb 2020 14:52:51 +0100
From:   David Hildenbrand <david@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     linux-mm@...ck.org, David Hildenbrand <david@...hat.com>,
        Segher Boessenkool <segher@...nel.crashing.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...nel.org>,
        Oscar Salvador <osalvador@...e.de>,
        Baoquan He <bhe@...hat.com>,
        Wei Yang <richardw.yang@...ux.intel.com>
Subject: [PATCH v1] mm/memory_hotplug: Easier calculation to get pages to next section boundary

Let's use a calculation that's easier to understand and calculates the
same result. Reusing existing macros makes this look nicer.

We always want to have the number of pages (> 0) to the next section
boundary, starting from the current pfn.

Suggested-by: Segher Boessenkool <segher@...nel.crashing.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Michal Hocko <mhocko@...nel.org>
Cc: Oscar Salvador <osalvador@...e.de>
Cc: Baoquan He <bhe@...hat.com>
Cc: Wei Yang <richardw.yang@...ux.intel.com>
Signed-off-by: David Hildenbrand <david@...hat.com>
---
 mm/memory_hotplug.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 0a54ffac8c68..c30191183c04 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -528,7 +528,8 @@ void __remove_pages(unsigned long pfn, unsigned long nr_pages,
 	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;
 	}
-- 
2.24.1