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SubjectRe: [PATCH] mm,memory_hotplug: Fix scan_movable_pages for gigantic hugepages
On Mon, 28 Jan 2019 14:53:09 -0800 Andrew Morton <akpm@linux-foundation.org> wrote:

> On Fri, 25 Jan 2019 08:58:33 +0100 Oscar Salvador <osalvador@suse.de> wrote:
>
> > On Wed, Jan 23, 2019 at 11:33:56AM +0100, David Hildenbrand wrote:
> > > If you use {} for the else case, please also do so for the if case.
> >
> > Diff on top:
> >
> > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> > index 25aee4f04a72..d5810e522b72 100644
> > --- a/mm/memory_hotplug.c
> > +++ b/mm/memory_hotplug.c
> > @@ -1338,9 +1338,9 @@ static unsigned long scan_movable_pages(unsigned long start, unsigned long end)
> > struct page *head = compound_head(page);
> >
> > if (hugepage_migration_supported(page_hstate(head)) &&
> > - page_huge_active(head))
> > + page_huge_active(head)) {
> > return pfn;
> > - else {
> > + } else {
> > unsigned long skip;
> >
> > skip = (1 << compound_order(head)) - (page - head);
> >
>
> The indenting is getting a bit deep also, so how about this?
>
> static unsigned long scan_movable_pages(unsigned long start, unsigned long end)
> {
> unsigned long pfn;
>
> for (pfn = start; pfn < end; pfn++) {
> struct page *page, *head;
>
> if (!pfn_valid(pfn))
> continue;
> page = pfn_to_page(pfn);
> if (PageLRU(page))
> return pfn;
> if (__PageMovable(page))
> return pfn;
>
> if (!PageHuge(page))
> continue;
> head = compound_head(page);
> if (hugepage_migration_supported(page_hstate(head)) &&
> page_huge_active(head)) {
> return pfn;

checkpatch pointed out that else-after-return isn't needed so we can do

static unsigned long scan_movable_pages(unsigned long start, unsigned long end)
{
unsigned long pfn;

for (pfn = start; pfn < end; pfn++) {
struct page *page, *head;
unsigned long skip;

if (!pfn_valid(pfn))
continue;
page = pfn_to_page(pfn);
if (PageLRU(page))
return pfn;
if (__PageMovable(page))
return pfn;

if (!PageHuge(page))
continue;
head = compound_head(page);
if (hugepage_migration_supported(page_hstate(head)) &&
page_huge_active(head))
return pfn;
skip = (1 << compound_order(head)) - (page - head);
pfn += skip - 1;
}
return 0;
}

--- a/mm/memory_hotplug.c~mmmemory_hotplug-fix-scan_movable_pages-for-gigantic-hugepages-fix
+++ a/mm/memory_hotplug.c
@@ -1305,28 +1305,27 @@ int test_pages_in_a_zone(unsigned long s
static unsigned long scan_movable_pages(unsigned long start, unsigned long end)
{
unsigned long pfn;
- struct page *page;
+
for (pfn = start; pfn < end; pfn++) {
- if (pfn_valid(pfn)) {
- page = pfn_to_page(pfn);
- if (PageLRU(page))
- return pfn;
- if (__PageMovable(page))
- return pfn;
- if (PageHuge(page)) {
- struct page *head = compound_head(page);
+ struct page *page, *head;
+ unsigned long skip;

- if (hugepage_migration_supported(page_hstate(head)) &&
- page_huge_active(head))
- return pfn;
- else {
- unsigned long skip;
+ if (!pfn_valid(pfn))
+ continue;
+ page = pfn_to_page(pfn);
+ if (PageLRU(page))
+ return pfn;
+ if (__PageMovable(page))
+ return pfn;

- skip = (1 << compound_order(head)) - (page - head);
- pfn += skip - 1;
- }
- }
- }
+ if (!PageHuge(page))
+ continue;
+ head = compound_head(page);
+ if (hugepage_migration_supported(page_hstate(head)) &&
+ page_huge_active(head))
+ return pfn;
+ skip = (1 << compound_order(head)) - (page - head);
+ pfn += skip - 1;
}
return 0;
}
_
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