mm/memory_hotplug: cleanup __remove_pages()

Let's drop the basically unused section stuff and simplify.

Also, let's use a shorter variant to calculate the number of pages to
the next section boundary.

Link: http://lkml.kernel.org/r/20191006085646.5768-11-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Pankaj Gupta <pagupta@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index a2b6ca2..4344e85 100644 (file)
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -516,25 +516,20 @@ static void __remove_section(unsigned long pfn, unsigned long nr_pages,
 void __remove_pages(unsigned long pfn, unsigned long nr_pages,
                    struct vmem_altmap *altmap)
 {
+       const unsigned long end_pfn = pfn + nr_pages;
+       unsigned long cur_nr_pages;
        unsigned long map_offset = 0;
-       unsigned long nr, start_sec, end_sec;
 
        map_offset = vmem_altmap_offset(altmap);
 
        if (check_pfn_span(pfn, nr_pages, "remove"))
                return;
 
-       start_sec = pfn_to_section_nr(pfn);
-       end_sec = pfn_to_section_nr(pfn + nr_pages - 1);
-       for (nr = start_sec; nr <= end_sec; nr++) {
-               unsigned long pfns;
-
+       for (; pfn < end_pfn; pfn += cur_nr_pages) {
                cond_resched();
-               pfns = min(nr_pages, PAGES_PER_SECTION
-                               - (pfn & ~PAGE_SECTION_MASK));
-               __remove_section(pfn, pfns, map_offset, altmap);
-               pfn += pfns;
-               nr_pages -= pfns;
+               /* Select all remaining pages up to the next section boundary */
+               cur_nr_pages = min(end_pfn - pfn, -(pfn | PAGE_SECTION_MASK));
+               __remove_section(pfn, cur_nr_pages, map_offset, altmap);
                map_offset = 0;
        }
 }