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-rw-r--r--include/linux/hugetlb.h6
-rw-r--r--mm/hugetlb.c71
-rw-r--r--mm/memory_hotplug.c42
-rw-r--r--mm/page_alloc.c11
-rw-r--r--mm/page_isolation.c14
5 files changed, 135 insertions, 9 deletions
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index d1db00790a84..2e02c4ed1035 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -68,6 +68,7 @@ void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed);
int dequeue_hwpoisoned_huge_page(struct page *page);
bool isolate_huge_page(struct page *page, struct list_head *list);
void putback_active_hugepage(struct page *page);
+bool is_hugepage_active(struct page *page);
void copy_huge_page(struct page *dst, struct page *src);
#ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE
@@ -138,6 +139,7 @@ static inline int dequeue_hwpoisoned_huge_page(struct page *page)
#define isolate_huge_page(p, l) false
#define putback_active_hugepage(p) do {} while (0)
+#define is_hugepage_active(x) false
static inline void copy_huge_page(struct page *dst, struct page *src)
{
}
@@ -377,6 +379,9 @@ static inline pgoff_t basepage_index(struct page *page)
return __basepage_index(page);
}
+extern void dissolve_free_huge_pages(unsigned long start_pfn,
+ unsigned long end_pfn);
+
#else /* CONFIG_HUGETLB_PAGE */
struct hstate {};
#define alloc_huge_page_node(h, nid) NULL
@@ -403,6 +408,7 @@ static inline pgoff_t basepage_index(struct page *page)
{
return page->index;
}
+#define dissolve_free_huge_pages(s, e) do {} while (0)
#endif /* CONFIG_HUGETLB_PAGE */
#endif /* _LINUX_HUGETLB_H */
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index d37b3b95c439..fb4293b93fd0 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -21,6 +21,7 @@
#include <linux/rmap.h>
#include <linux/swap.h>
#include <linux/swapops.h>
+#include <linux/page-isolation.h>
#include <asm/page.h>
#include <asm/pgtable.h>
@@ -522,9 +523,15 @@ static struct page *dequeue_huge_page_node(struct hstate *h, int nid)
{
struct page *page;
- if (list_empty(&h->hugepage_freelists[nid]))
+ list_for_each_entry(page, &h->hugepage_freelists[nid], lru)
+ if (!is_migrate_isolate_page(page))
+ break;
+ /*
+ * if 'non-isolated free hugepage' not found on the list,
+ * the allocation fails.
+ */
+ if (&h->hugepage_freelists[nid] == &page->lru)
return NULL;
- page = list_entry(h->hugepage_freelists[nid].next, struct page, lru);
list_move(&page->lru, &h->hugepage_activelist);
set_page_refcounted(page);
h->free_huge_pages--;
@@ -878,6 +885,44 @@ static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
return ret;
}
+/*
+ * Dissolve a given free hugepage into free buddy pages. This function does
+ * nothing for in-use (including surplus) hugepages.
+ */
+static void dissolve_free_huge_page(struct page *page)
+{
+ spin_lock(&hugetlb_lock);
+ if (PageHuge(page) && !page_count(page)) {
+ struct hstate *h = page_hstate(page);
+ int nid = page_to_nid(page);
+ list_del(&page->lru);
+ h->free_huge_pages--;
+ h->free_huge_pages_node[nid]--;
+ update_and_free_page(h, page);
+ }
+ spin_unlock(&hugetlb_lock);
+}
+
+/*
+ * Dissolve free hugepages in a given pfn range. Used by memory hotplug to
+ * make specified memory blocks removable from the system.
+ * Note that start_pfn should aligned with (minimum) hugepage size.
+ */
+void dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn)
+{
+ unsigned int order = 8 * sizeof(void *);
+ unsigned long pfn;
+ struct hstate *h;
+
+ /* Set scan step to minimum hugepage size */
+ for_each_hstate(h)
+ if (order > huge_page_order(h))
+ order = huge_page_order(h);
+ VM_BUG_ON(!IS_ALIGNED(start_pfn, 1 << order));
+ for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << order)
+ dissolve_free_huge_page(pfn_to_page(pfn));
+}
+
static struct page *alloc_buddy_huge_page(struct hstate *h, int nid)
{
struct page *page;
@@ -3457,3 +3502,25 @@ void putback_active_hugepage(struct page *page)
spin_unlock(&hugetlb_lock);
put_page(page);
}
+
+bool is_hugepage_active(struct page *page)
+{
+ VM_BUG_ON(!PageHuge(page));
+ /*
+ * This function can be called for a tail page because the caller,
+ * scan_movable_pages, scans through a given pfn-range which typically
+ * covers one memory block. In systems using gigantic hugepage (1GB
+ * for x86_64,) a hugepage is larger than a memory block, and we don't
+ * support migrating such large hugepages for now, so return false
+ * when called for tail pages.
+ */
+ if (PageTail(page))
+ return false;
+ /*
+ * Refcount of a hwpoisoned hugepages is 1, but they are not active,
+ * so we should return false for them.
+ */
+ if (unlikely(PageHWPoison(page)))
+ return false;
+ return page_count(page) > 0;
+}
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index d595606728f9..0eb1a1df649d 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -30,6 +30,7 @@
#include <linux/mm_inline.h>
#include <linux/firmware-map.h>
#include <linux/stop_machine.h>
+#include <linux/hugetlb.h>
#include <asm/tlbflush.h>
@@ -1230,10 +1231,12 @@ static int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
}
/*
- * Scanning pfn is much easier than scanning lru list.
- * Scan pfn from start to end and Find LRU page.
+ * Scan pfn range [start,end) to find movable/migratable pages (LRU pages
+ * and hugepages). We scan pfn because it's much easier than scanning over
+ * linked list. This function returns the pfn of the first found movable
+ * page if it's found, otherwise 0.
*/
-static unsigned long scan_lru_pages(unsigned long start, unsigned long end)
+static unsigned long scan_movable_pages(unsigned long start, unsigned long end)
{
unsigned long pfn;
struct page *page;
@@ -1242,6 +1245,13 @@ static unsigned long scan_lru_pages(unsigned long start, unsigned long end)
page = pfn_to_page(pfn);
if (PageLRU(page))
return pfn;
+ if (PageHuge(page)) {
+ if (is_hugepage_active(page))
+ return pfn;
+ else
+ pfn = round_up(pfn + 1,
+ 1 << compound_order(page)) - 1;
+ }
}
}
return 0;
@@ -1262,6 +1272,19 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
if (!pfn_valid(pfn))
continue;
page = pfn_to_page(pfn);
+
+ if (PageHuge(page)) {
+ struct page *head = compound_head(page);
+ pfn = page_to_pfn(head) + (1<<compound_order(head)) - 1;
+ if (compound_order(head) > PFN_SECTION_SHIFT) {
+ ret = -EBUSY;
+ break;
+ }
+ if (isolate_huge_page(page, &source))
+ move_pages -= 1 << compound_order(head);
+ continue;
+ }
+
if (!get_page_unless_zero(page))
continue;
/*
@@ -1294,7 +1317,7 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
}
if (!list_empty(&source)) {
if (not_managed) {
- putback_lru_pages(&source);
+ putback_movable_pages(&source);
goto out;
}
@@ -1305,7 +1328,7 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
ret = migrate_pages(&source, alloc_migrate_target, 0,
MIGRATE_SYNC, MR_MEMORY_HOTPLUG);
if (ret)
- putback_lru_pages(&source);
+ putback_movable_pages(&source);
}
out:
return ret;
@@ -1548,8 +1571,8 @@ repeat:
drain_all_pages();
}
- pfn = scan_lru_pages(start_pfn, end_pfn);
- if (pfn) { /* We have page on LRU */
+ pfn = scan_movable_pages(start_pfn, end_pfn);
+ if (pfn) { /* We have movable pages */
ret = do_migrate_range(pfn, end_pfn);
if (!ret) {
drain = 1;
@@ -1568,6 +1591,11 @@ repeat:
yield();
/* drain pcp pages, this is synchronous. */
drain_all_pages();
+ /*
+ * dissolve free hugepages in the memory block before doing offlining
+ * actually in order to make hugetlbfs's object counting consistent.
+ */
+ dissolve_free_huge_pages(start_pfn, end_pfn);
/* check again */
offlined_pages = check_pages_isolated(start_pfn, end_pfn);
if (offlined_pages < 0) {
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 7c3f8d7e2d8e..f7cc08dad26a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6008,6 +6008,17 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
continue;
page = pfn_to_page(check);
+
+ /*
+ * Hugepages are not in LRU lists, but they're movable.
+ * We need not scan over tail pages bacause we don't
+ * handle each tail page individually in migration.
+ */
+ if (PageHuge(page)) {
+ iter = round_up(iter + 1, 1<<compound_order(page)) - 1;
+ continue;
+ }
+
/*
* We can't use page_count without pin a page
* because another CPU can free compound page.
diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index 0cee10ffb98d..d1473b2e9481 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -6,6 +6,7 @@
#include <linux/page-isolation.h>
#include <linux/pageblock-flags.h>
#include <linux/memory.h>
+#include <linux/hugetlb.h>
#include "internal.h"
int set_migratetype_isolate(struct page *page, bool skip_hwpoisoned_pages)
@@ -252,6 +253,19 @@ struct page *alloc_migrate_target(struct page *page, unsigned long private,
{
gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE;
+ /*
+ * TODO: allocate a destination hugepage from a nearest neighbor node,
+ * accordance with memory policy of the user process if possible. For
+ * now as a simple work-around, we use the next node for destination.
+ */
+ if (PageHuge(page)) {
+ nodemask_t src = nodemask_of_node(page_to_nid(page));
+ nodemask_t dst;
+ nodes_complement(dst, src);
+ return alloc_huge_page_node(page_hstate(compound_head(page)),
+ next_node(page_to_nid(page), dst));
+ }
+
if (PageHighMem(page))
gfp_mask |= __GFP_HIGHMEM;