1 files changed, 36 insertions, 10 deletions

diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
index ba2a2596fb4e..45e93a545dd7 100644
--- a/mm/hugetlb_vmemmap.c
+++ b/mm/hugetlb_vmemmap.c
@@ -11,6 +11,7 @@
 #define pr_fmt(fmt)	"HugeTLB: " fmt
 
 #include <linux/pgtable.h>
+#include <linux/moduleparam.h>
 #include <linux/bootmem_info.h>
 #include <asm/pgalloc.h>
 #include <asm/tlbflush.h>
@@ -202,12 +203,7 @@ static int vmemmap_remap_range(unsigned long start, unsigned long end,
 			return ret;
 	} while (pgd++, addr = next, addr != end);
 
-	/*
-	 * We only change the mapping of the vmemmap virtual address range
-	 * [@start + PAGE_SIZE, end), so we only need to flush the TLB which
-	 * belongs to the range.
-	 */
-	flush_tlb_kernel_range(start + PAGE_SIZE, end);
+	flush_tlb_kernel_range(start, end);
 
 	return 0;
 }
@@ -231,10 +227,8 @@ static void free_vmemmap_page_list(struct list_head *list)
 {
 	struct page *page, *next;
 
-	list_for_each_entry_safe(page, next, list, lru) {
-		list_del(&page->lru);
+	list_for_each_entry_safe(page, next, list, lru)
 		free_vmemmap_page(page);
-	}
 }
 
 static void vmemmap_remap_pte(pte_t *pte, unsigned long addr,
@@ -245,9 +239,23 @@ static void vmemmap_remap_pte(pte_t *pte, unsigned long addr,
 	 * to the tail pages.
 	 */
 	pgprot_t pgprot = PAGE_KERNEL_RO;
-	pte_t entry = mk_pte(walk->reuse_page, pgprot);
 	struct page *page = pte_page(*pte);
+	pte_t entry;
 
+	/* Remapping the head page requires r/w */
+	if (unlikely(addr == walk->reuse_addr)) {
+		pgprot = PAGE_KERNEL;
+		list_del(&walk->reuse_page->lru);
+
+		/*
+		 * Makes sure that preceding stores to the page contents from
+		 * vmemmap_remap_free() become visible before the set_pte_at()
+		 * write.
+		 */
+		smp_wmb();
+	}
+
+	entry = mk_pte(walk->reuse_page, pgprot);
 	list_add_tail(&page->lru, walk->vmemmap_pages);
 	set_pte_at(&init_mm, addr, pte, entry);
 }
@@ -316,6 +324,24 @@ static int vmemmap_remap_free(unsigned long start, unsigned long end,
 		.reuse_addr	= reuse,
 		.vmemmap_pages	= &vmemmap_pages,
 	};
+	int nid = page_to_nid((struct page *)start);
+	gfp_t gfp_mask = GFP_KERNEL | __GFP_THISNODE | __GFP_NORETRY |
+			__GFP_NOWARN;
+
+	/*
+	 * Allocate a new head vmemmap page to avoid breaking a contiguous
+	 * block of struct page memory when freeing it back to page allocator
+	 * in free_vmemmap_page_list(). This will allow the likely contiguous
+	 * struct page backing memory to be kept contiguous and allowing for
+	 * more allocations of hugepages. Fallback to the currently
+	 * mapped head page in case should it fail to allocate.
+	 */
+	walk.reuse_page = alloc_pages_node(nid, gfp_mask, 0);
+	if (walk.reuse_page) {
+		copy_page(page_to_virt(walk.reuse_page),
+			  (void *)walk.reuse_addr);
+		list_add(&walk.reuse_page->lru, &vmemmap_pages);
+	}
 
 	/*
 	 * In order to make remapping routine most efficient for the huge pages,