mm/page_alloc: simplify __offline_isolated_pages()

offline_pages() is the only user.  __offline_isolated_pages() never gets
called with ranges that contain memory holes and we no longer care about
the return value.  Drop the return value handling and all pfn_valid()
checks.

Update the documentation.

Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Charan Teja Reddy <charante@codeaurora.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michel Lespinasse <walken@google.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/20200819175957.28465-5-david@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index c0faa7a..76b3140 100644 (file)
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -103,8 +103,8 @@ extern int online_pages(unsigned long pfn, unsigned long nr_pages,
                        int online_type, int nid);
 extern struct zone *test_pages_in_a_zone(unsigned long start_pfn,
                                         unsigned long end_pfn);
-extern unsigned long __offline_isolated_pages(unsigned long start_pfn,
-                                               unsigned long end_pfn);
+extern void __offline_isolated_pages(unsigned long start_pfn,
+                                    unsigned long end_pfn);
 
 typedef void (*online_page_callback_t)(struct page *page, unsigned int order);
 

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 7fa55d9..acc04ca 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -8704,35 +8704,21 @@ void zone_pcp_reset(struct zone *zone)
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
 /*
- * All pages in the range must be in a single zone and isolated
- * before calling this.
+ * All pages in the range must be in a single zone, must not contain holes,
+ * must span full sections, and must be isolated before calling this function.
  */
-unsigned long
-__offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
+void __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
 {
+       unsigned long pfn = start_pfn;
        struct page *page;
        struct zone *zone;
        unsigned int order;
-       unsigned long pfn;
        unsigned long flags;
-       unsigned long offlined_pages = 0;
-
-       /* find the first valid pfn */
-       for (pfn = start_pfn; pfn < end_pfn; pfn++)
-               if (pfn_valid(pfn))
-                       break;
-       if (pfn == end_pfn)
-               return offlined_pages;
 
        offline_mem_sections(pfn, end_pfn);
        zone = page_zone(pfn_to_page(pfn));
        spin_lock_irqsave(&zone->lock, flags);
-       pfn = start_pfn;
        while (pfn < end_pfn) {
-               if (!pfn_valid(pfn)) {
-                       pfn++;
-                       continue;
-               }
                page = pfn_to_page(pfn);
                /*
                 * The HWPoisoned page may be not in buddy system, and
@@ -8740,7 +8726,6 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
                 */
                if (unlikely(!PageBuddy(page) && PageHWPoison(page))) {
                        pfn++;
-                       offlined_pages++;
                        continue;
                }
                /*
@@ -8751,20 +8736,16 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
                        BUG_ON(page_count(page));
                        BUG_ON(PageBuddy(page));
                        pfn++;
-                       offlined_pages++;
                        continue;
                }
 
                BUG_ON(page_count(page));
                BUG_ON(!PageBuddy(page));
                order = page_order(page);
-               offlined_pages += 1 << order;
                del_page_from_free_list(page, zone, order);
                pfn += (1 << order);
        }
        spin_unlock_irqrestore(&zone->lock, flags);
-
-       return offlined_pages;
 }
 #endif