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    SubjectRe: [PATCH v1 06/11] mm/memory_hotplug: drop nr_isolate_pageblock in offline_pages()
    On Wed 19-08-20 12:11:52, David Hildenbrand wrote:
    > 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.
    >
    > Cc: Andrew Morton <akpm@linux-foundation.org>
    > Cc: 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: Oscar Salvador <osalvador@suse.de>
    > Signed-off-by: David Hildenbrand <david@redhat.com>

    Acked-by: Michal Hocko <mhocko@suse.com>

    > ---
    > mm/memory_hotplug.c | 5 ++---
    > 1 file changed, 2 insertions(+), 3 deletions(-)
    >
    > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
    > index 50aa5df696e9d..098361fcb4504 100644
    > --- a/mm/memory_hotplug.c
    > +++ b/mm/memory_hotplug.c
    > @@ -1460,10 +1460,10 @@ 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) */
    > @@ -1507,7 +1507,6 @@ 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;
    > @@ -1569,7 +1568,7 @@ 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 */
    > --
    > 2.26.2
    >

    --
    Michal Hocko
    SUSE Labs

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