mm/memory_hotplug: drop nr_isolate_pageblock in offline_pages()

We make sure that we cannot have any memory holes right at the beginning
of offline_pages() and we only support to online/offline full sections.
Both, sections and pageblocks are a power of two in size, and sections
always span full pageblocks.

We can directly calculate the number of isolated pageblocks from nr_pages.

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/20200819175957.28465-6-david@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index c3977ce..9052444 100644 (file)
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1471,10 +1471,10 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages)
 {
        const unsigned long end_pfn = start_pfn + nr_pages;
        unsigned long pfn, system_ram_pages = 0;
-       int ret, node, nr_isolate_pageblock;
        unsigned long flags;
        struct zone *zone;
        struct memory_notify arg;
+       int ret, node;
        char *reason;
 
        /* We can only offline full sections (e.g., SECTION_IS_ONLINE) */
@@ -1518,7 +1518,6 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages)
                reason = "failure to isolate range";
                goto failed_removal;
        }
-       nr_isolate_pageblock = ret;
 
        arg.start_pfn = start_pfn;
        arg.nr_pages = nr_pages;
@@ -1596,7 +1595,7 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages)
         * pageblocks zone counter here.
         */
        spin_lock_irqsave(&zone->lock, flags);
-       zone->nr_isolate_pageblock -= nr_isolate_pageblock;
+       zone->nr_isolate_pageblock -= nr_pages / pageblock_nr_pages;
        spin_unlock_irqrestore(&zone->lock, flags);
 
        /* removal success */