From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
This commit introduces alloc_contig_free_pages() function
which allocates (ie. removes from buddy system) free pages
in range. Caller has to guarantee that all pages in range
are in buddy system.
Along with alloc_contig_free_pages(), a free_contig_pages()
function is provided which frees (or a subset of) pages
allocated with alloc_contig_free_pages().
I, Michal Nazarewicz, have modified the
alloc_contig_free_pages() function slightly from the original
version, mostly to make it easier to allocate note MAX_ORDER
aligned pages. This is done by making the function return
a pfn of a page one past the one allocated which may be
further then caller requested.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Signed-off-by: Michal Nazarewicz <m.nazarewicz@xxxxxxxxxxx>
Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
---
include/linux/page-isolation.h | 3 ++
mm/page_alloc.c | 42 ++++++++++++++++++++++++++++++++++++++++
2 files changed, 45 insertions(+), 0 deletions(-)
diff --git a/include/linux/page-isolation.h b/include/linux/page-isolation.h
index 58cdbac..f1417ed 100644
--- a/include/linux/page-isolation.h
+++ b/include/linux/page-isolation.h
@@ -32,6 +32,9 @@ test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn);
*/
extern int set_migratetype_isolate(struct page *page);
extern void unset_migratetype_isolate(struct page *page);
+extern unsigned long alloc_contig_freed_pages(unsigned long start,
+ unsigned long end, gfp_t flag);
+extern void free_contig_pages(struct page *page, int nr_pages);
/*
* For migration.
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 07a6544..6dd2854 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5424,6 +5424,48 @@ out:
spin_unlock_irqrestore(&zone->lock, flags);
}
+unsigned long alloc_contig_freed_pages(unsigned long start,
+ unsigned long end, gfp_t flag)
+{
+ unsigned long pfn = start, count;
+ struct page *page;
+ struct zone *zone;
+ int order;
+
+ VM_BUG_ON(!pfn_valid(pfn));
+ page = pfn_to_page(pfn);
+
+ zone = page_zone(page);
+ spin_lock_irq(&zone->lock);
+ for (;;) {
+ VM_BUG_ON(page_count(page) || !PageBuddy(page));
+ list_del(&page->lru);
+ order = page_order(page);
+ zone->free_area[order].nr_free--;
+ rmv_page_order(page);
+ __mod_zone_page_state(zone, NR_FREE_PAGES, -(1UL << order));
+ pfn += 1 << order;
+ if (pfn >= end)
+ break;
+ VM_BUG_ON(!pfn_valid(pfn));
+ page += 1 << order;
+ }
+ spin_unlock_irq(&zone->lock);
+
+ /* After this, pages in the range can be freed one be one */
+ page = pfn_to_page(start);
+ for (count = pfn - start; count; --count, ++page)
+ prep_new_page(page, 0, flag);
+
+ return pfn;
+}
+
+void free_contig_pages(struct page *page, int nr_pages)
+{
+ for (; nr_pages; --nr_pages, ++page)
+ __free_page(page);
+}
+
#ifdef CONFIG_MEMORY_HOTREMOVE
/*
* All pages in the range must be isolated before calling this.
--
1.7.2.3
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