When we free a HugeTLB page to the buddy allocator, we should allocate the
vmemmap pages associated with it. We can do that in the __free_hugepage()
before freeing it to buddy.
Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
---
include/linux/mm.h | 1 +
mm/hugetlb.c | 2 ++
mm/hugetlb_vmemmap.c | 11 +++++++++
mm/hugetlb_vmemmap.h | 5 ++++
mm/sparse-vmemmap.c | 69 +++++++++++++++++++++++++++++++++++++++++++++++++++-
5 files changed, 87 insertions(+), 1 deletion(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index ab02e405a979..5b8dc36e4d20 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3006,6 +3006,7 @@ static inline void print_vma_addr(char *prefix, unsigned long rip)
#endif
void vmemmap_remap_reuse(unsigned long start, unsigned long size);
+void vmemmap_remap_restore(unsigned long start, unsigned long size);
void *sparse_buffer_alloc(unsigned long size);
struct page * __populate_section_memmap(unsigned long pfn,
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 0ff9b90e524f..542e6cb81321 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1362,6 +1362,8 @@ static void __free_hugepage(struct hstate *h, struct page *page)
{
int i;
+ alloc_huge_page_vmemmap(h, page);
+
for (i = 0; i < pages_per_huge_page(h); i++) {
page[i].flags &= ~(1 << PG_locked | 1 << PG_error |
1 << PG_referenced | 1 << PG_dirty |
diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
index 6d4e77a2b6c7..02201c2e3dfa 100644
--- a/mm/hugetlb_vmemmap.c
+++ b/mm/hugetlb_vmemmap.c
@@ -185,6 +185,17 @@ static inline unsigned long free_vmemmap_pages_size_per_hpage(struct hstate *h)
return (unsigned long)free_vmemmap_pages_per_hpage(h) << PAGE_SHIFT;
}
+void alloc_huge_page_vmemmap(struct hstate *h, struct page *head)
+{
+ unsigned long vmemmap_addr = (unsigned long)head;
+
+ if (!free_vmemmap_pages_per_hpage(h))
+ return;
+
+ vmemmap_remap_restore(vmemmap_addr + RESERVE_VMEMMAP_SIZE,
+ free_vmemmap_pages_size_per_hpage(h));
+}
+
void free_huge_page_vmemmap(struct hstate *h, struct page *head)
{
unsigned long vmemmap_addr = (unsigned long)head;
diff --git a/mm/hugetlb_vmemmap.h b/mm/hugetlb_vmemmap.h
index 01f8637adbe0..b2c8d2f11d48 100644
--- a/mm/hugetlb_vmemmap.h
+++ b/mm/hugetlb_vmemmap.h
@@ -11,6 +11,7 @@
#include <linux/hugetlb.h>
#ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP
+void alloc_huge_page_vmemmap(struct hstate *h, struct page *head);
void free_huge_page_vmemmap(struct hstate *h, struct page *head);
/*
@@ -25,6 +26,10 @@ static inline unsigned int free_vmemmap_pages_per_hpage(struct hstate *h)
return 0;
}
#else
+static inline void alloc_huge_page_vmemmap(struct hstate *h, struct page *head)
+{
+}
+
static inline void free_huge_page_vmemmap(struct hstate *h, struct page *head)
{
}
diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
index 78c527617e8d..ffcf092c92ed 100644
--- a/mm/sparse-vmemmap.c
+++ b/mm/sparse-vmemmap.c
@@ -29,6 +29,7 @@
#include <linux/sched.h>
#include <linux/pgtable.h>
#include <linux/bootmem_info.h>
+#include <linux/delay.h>
#include <asm/dma.h>
#include <asm/pgalloc.h>
@@ -39,7 +40,8 @@
*
* @rmap_pte: called for each non-empty PTE (lowest-level) entry.
* @reuse: the page which is reused for the tail vmemmap pages.
- * @vmemmap_pages: the list head of the vmemmap pages that can be freed.
+ * @vmemmap_pages: the list head of the vmemmap pages that can be freed
+ * or is mapped from.
*/
struct vmemmap_rmap_walk {
void (*rmap_pte)(pte_t *pte, unsigned long addr,
@@ -54,6 +56,9 @@ struct vmemmap_rmap_walk {
*/
#define VMEMMAP_TAIL_PAGE_REUSE -1
+/* The gfp mask of allocating vmemmap page */
+#define GFP_VMEMMAP_PAGE (GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_NOWARN)
+
static void vmemmap_pte_range(pmd_t *pmd, unsigned long addr,
unsigned long end, struct vmemmap_rmap_walk *walk)
{
@@ -200,6 +205,68 @@ void vmemmap_remap_reuse(unsigned long start, unsigned long size)
free_vmemmap_page_list(&vmemmap_pages);
}
+static void vmemmap_remap_restore_pte(pte_t *pte, unsigned long addr,
+ struct vmemmap_rmap_walk *walk)
+{
+ pgprot_t pgprot = PAGE_KERNEL;
+ struct page *page;
+ void *to;
+
+ BUG_ON(pte_page(*pte) != walk->reuse);
+
+ page = list_first_entry(walk->vmemmap_pages, struct page, lru);
+ list_del(&page->lru);
+ to = page_to_virt(page);
+ copy_page(to, page_to_virt(walk->reuse));
+
+ set_pte_at(&init_mm, addr, pte, mk_pte(page, pgprot));
+}
+
+static void alloc_vmemmap_page_list(struct list_head *list,
+ unsigned long nr_pages)
+{
+ while (nr_pages--) {
+ struct page *page;
+
+retry:
+ page = alloc_page(GFP_VMEMMAP_PAGE);
+ if (unlikely(!page)) {
+ msleep(100);
+ /*
+ * We should retry infinitely, because we cannot
+ * handle allocation failures. Once we allocate
+ * vmemmap pages successfully, then we can free
+ * a HugeTLB page.
+ */
+ goto retry;
+ }
+ list_add_tail(&page->lru, list);
+ }
+}
+
+/**
+ * vmemmap_remap_restore - remap the vmemmap virtual address range
+ * [start, start + size) to the page respectively
+ * which from the @vmemmap_pages
+ * @start: start address of the vmemmap virtual address range
+ * @end: size of the vmemmap virtual address range
+ */
+void vmemmap_remap_restore(unsigned long start, unsigned long size)
+{
+ LIST_HEAD(vmemmap_pages);
+ unsigned long end = start + size;
+
+ struct vmemmap_rmap_walk walk = {
+ .rmap_pte = vmemmap_remap_restore_pte,
+ .vmemmap_pages = &vmemmap_pages,
+ };
+
+ might_sleep();
+
+ alloc_vmemmap_page_list(&vmemmap_pages, size >> PAGE_SHIFT);
+ vmemmap_remap_range(start, end, &walk);
+}
+
/*
* Allocate a block of memory to be used to back the virtual memory map
* or to back the page tables that are used to create the mapping.
--
2.11.0
