1 files changed, 151 insertions, 76 deletions

diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index aefdf3a812a1..af61b95c89e4 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -1026,18 +1026,64 @@ static inline bool is_pte_pages_stable(pte_t *dst_pte, pte_t *src_pte,
 	       pmd_same(dst_pmdval, pmdp_get_lockless(dst_pmd));
 }
 
-static int move_present_pte(struct mm_struct *mm,
-			    struct vm_area_struct *dst_vma,
-			    struct vm_area_struct *src_vma,
-			    unsigned long dst_addr, unsigned long src_addr,
-			    pte_t *dst_pte, pte_t *src_pte,
-			    pte_t orig_dst_pte, pte_t orig_src_pte,
-			    pmd_t *dst_pmd, pmd_t dst_pmdval,
-			    spinlock_t *dst_ptl, spinlock_t *src_ptl,
-			    struct folio *src_folio)
+/*
+ * Checks if the two ptes and the corresponding folio are eligible for batched
+ * move. If so, then returns pointer to the locked folio. Otherwise, returns NULL.
+ *
+ * NOTE: folio's reference is not required as the whole operation is within
+ * PTL's critical section.
+ */
+static struct folio *check_ptes_for_batched_move(struct vm_area_struct *src_vma,
+						 unsigned long src_addr,
+						 pte_t *src_pte, pte_t *dst_pte,
+						 struct anon_vma *src_anon_vma)
+{
+	pte_t orig_dst_pte, orig_src_pte;
+	struct folio *folio;
+
+	orig_dst_pte = ptep_get(dst_pte);
+	if (!pte_none(orig_dst_pte))
+		return NULL;
+
+	orig_src_pte = ptep_get(src_pte);
+	if (!pte_present(orig_src_pte) || is_zero_pfn(pte_pfn(orig_src_pte)))
+		return NULL;
+
+	folio = vm_normal_folio(src_vma, src_addr, orig_src_pte);
+	if (!folio || !folio_trylock(folio))
+		return NULL;
+	if (!PageAnonExclusive(&folio->page) || folio_test_large(folio) ||
+	    folio_anon_vma(folio) != src_anon_vma) {
+		folio_unlock(folio);
+		return NULL;
+	}
+	return folio;
+}
+
+/*
+ * Moves src folios to dst in a batch as long as they share the same
+ * anon_vma as the first folio, are not large, and can successfully
+ * take the lock via folio_trylock().
+ */
+static long move_present_ptes(struct mm_struct *mm,
+			      struct vm_area_struct *dst_vma,
+			      struct vm_area_struct *src_vma,
+			      unsigned long dst_addr, unsigned long src_addr,
+			      pte_t *dst_pte, pte_t *src_pte,
+			      pte_t orig_dst_pte, pte_t orig_src_pte,
+			      pmd_t *dst_pmd, pmd_t dst_pmdval,
+			      spinlock_t *dst_ptl, spinlock_t *src_ptl,
+			      struct folio **first_src_folio, unsigned long len,
+			      struct anon_vma *src_anon_vma)
 {
 	int err = 0;
+	struct folio *src_folio = *first_src_folio;
+	unsigned long src_start = src_addr;
+	unsigned long src_end;
 
+	len = pmd_addr_end(dst_addr, dst_addr + len) - dst_addr;
+	src_end = pmd_addr_end(src_addr, src_addr + len);
+	flush_cache_range(src_vma, src_addr, src_end);
 	double_pt_lock(dst_ptl, src_ptl);
 
 	if (!is_pte_pages_stable(dst_pte, src_pte, orig_dst_pte, orig_src_pte,
@@ -1051,31 +1097,56 @@ static int move_present_pte(struct mm_struct *mm,
 		err = -EBUSY;
 		goto out;
 	}
+	/* It's safe to drop the reference now as the page-table is holding one. */
+	folio_put(*first_src_folio);
+	*first_src_folio = NULL;
+	arch_enter_lazy_mmu_mode();
+
+	while (true) {
+		orig_src_pte = ptep_get_and_clear(mm, src_addr, src_pte);
+		/* Folio got pinned from under us. Put it back and fail the move. */
+		if (folio_maybe_dma_pinned(src_folio)) {
+			set_pte_at(mm, src_addr, src_pte, orig_src_pte);
+			err = -EBUSY;
+			break;
+		}
 
-	orig_src_pte = ptep_clear_flush(src_vma, src_addr, src_pte);
-	/* Folio got pinned from under us. Put it back and fail the move. */
-	if (folio_maybe_dma_pinned(src_folio)) {
-		set_pte_at(mm, src_addr, src_pte, orig_src_pte);
-		err = -EBUSY;
-		goto out;
-	}
-
-	folio_move_anon_rmap(src_folio, dst_vma);
-	src_folio->index = linear_page_index(dst_vma, dst_addr);
+		folio_move_anon_rmap(src_folio, dst_vma);
+		src_folio->index = linear_page_index(dst_vma, dst_addr);
 
-	orig_dst_pte = folio_mk_pte(src_folio, dst_vma->vm_page_prot);
-	/* Set soft dirty bit so userspace can notice the pte was moved */
+		orig_dst_pte = folio_mk_pte(src_folio, dst_vma->vm_page_prot);
+		/* Set soft dirty bit so userspace can notice the pte was moved */
 #ifdef CONFIG_MEM_SOFT_DIRTY
-	orig_dst_pte = pte_mksoft_dirty(orig_dst_pte);
+		orig_dst_pte = pte_mksoft_dirty(orig_dst_pte);
 #endif
-	if (pte_dirty(orig_src_pte))
-		orig_dst_pte = pte_mkdirty(orig_dst_pte);
-	orig_dst_pte = pte_mkwrite(orig_dst_pte, dst_vma);
+		if (pte_dirty(orig_src_pte))
+			orig_dst_pte = pte_mkdirty(orig_dst_pte);
+		orig_dst_pte = pte_mkwrite(orig_dst_pte, dst_vma);
+		set_pte_at(mm, dst_addr, dst_pte, orig_dst_pte);
+
+		src_addr += PAGE_SIZE;
+		if (src_addr == src_end)
+			break;
+		dst_addr += PAGE_SIZE;
+		dst_pte++;
+		src_pte++;
+
+		folio_unlock(src_folio);
+		src_folio = check_ptes_for_batched_move(src_vma, src_addr, src_pte,
+							dst_pte, src_anon_vma);
+		if (!src_folio)
+			break;
+	}
 
-	set_pte_at(mm, dst_addr, dst_pte, orig_dst_pte);
+	arch_leave_lazy_mmu_mode();
+	if (src_addr > src_start)
+		flush_tlb_range(src_vma, src_start, src_addr);
+
+	if (src_folio)
+		folio_unlock(src_folio);
 out:
 	double_pt_unlock(dst_ptl, src_ptl);
-	return err;
+	return src_addr > src_start ? src_addr - src_start : err;
 }
 
 static int move_swap_pte(struct mm_struct *mm, struct vm_area_struct *dst_vma,
@@ -1140,7 +1211,7 @@ static int move_swap_pte(struct mm_struct *mm, struct vm_area_struct *dst_vma,
 	set_pte_at(mm, dst_addr, dst_pte, orig_src_pte);
 	double_pt_unlock(dst_ptl, src_ptl);
 
-	return 0;
+	return PAGE_SIZE;
 }
 
 static int move_zeropage_pte(struct mm_struct *mm,
@@ -1167,20 +1238,20 @@ static int move_zeropage_pte(struct mm_struct *mm,
 	set_pte_at(mm, dst_addr, dst_pte, zero_pte);
 	double_pt_unlock(dst_ptl, src_ptl);
 
-	return 0;
+	return PAGE_SIZE;
 }
 
 
 /*
- * The mmap_lock for reading is held by the caller. Just move the page
- * from src_pmd to dst_pmd if possible, and return true if succeeded
- * in moving the page.
+ * The mmap_lock for reading is held by the caller. Just move the page(s)
+ * from src_pmd to dst_pmd if possible, and return number of bytes moved.
+ * On failure, an error code is returned.
  */
-static int move_pages_pte(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd,
-			  struct vm_area_struct *dst_vma,
-			  struct vm_area_struct *src_vma,
-			  unsigned long dst_addr, unsigned long src_addr,
-			  __u64 mode)
+static long move_pages_ptes(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd,
+			    struct vm_area_struct *dst_vma,
+			    struct vm_area_struct *src_vma,
+			    unsigned long dst_addr, unsigned long src_addr,
+			    unsigned long len, __u64 mode)
 {
 	swp_entry_t entry;
 	struct swap_info_struct *si = NULL;
@@ -1194,11 +1265,10 @@ static int move_pages_pte(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd,
 	struct folio *src_folio = NULL;
 	struct anon_vma *src_anon_vma = NULL;
 	struct mmu_notifier_range range;
-	int err = 0;
+	long ret = 0;
 
-	flush_cache_range(src_vma, src_addr, src_addr + PAGE_SIZE);
 	mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm,
-				src_addr, src_addr + PAGE_SIZE);
+				src_addr, src_addr + len);
 	mmu_notifier_invalidate_range_start(&range);
 retry:
 	/*
@@ -1212,7 +1282,7 @@ retry:
 
 	/* Retry if a huge pmd materialized from under us */
 	if (unlikely(!dst_pte)) {
-		err = -EAGAIN;
+		ret = -EAGAIN;
 		goto out;
 	}
 
@@ -1231,14 +1301,14 @@ retry:
 	 * transparent huge pages under us.
 	 */
 	if (unlikely(!src_pte)) {
-		err = -EAGAIN;
+		ret = -EAGAIN;
 		goto out;
 	}
 
 	/* Sanity checks before the operation */
 	if (pmd_none(*dst_pmd) || pmd_none(*src_pmd) ||
 	    pmd_trans_huge(*dst_pmd) || pmd_trans_huge(*src_pmd)) {
-		err = -EINVAL;
+		ret = -EINVAL;
 		goto out;
 	}
 
@@ -1246,7 +1316,7 @@ retry:
 	orig_dst_pte = ptep_get(dst_pte);
 	spin_unlock(dst_ptl);
 	if (!pte_none(orig_dst_pte)) {
-		err = -EEXIST;
+		ret = -EEXIST;
 		goto out;
 	}
 
@@ -1255,21 +1325,21 @@ retry:
 	spin_unlock(src_ptl);
 	if (pte_none(orig_src_pte)) {
 		if (!(mode & UFFDIO_MOVE_MODE_ALLOW_SRC_HOLES))
-			err = -ENOENT;
+			ret = -ENOENT;
 		else /* nothing to do to move a hole */
-			err = 0;
+			ret = PAGE_SIZE;
 		goto out;
 	}
 
 	/* If PTE changed after we locked the folio them start over */
 	if (src_folio && unlikely(!pte_same(src_folio_pte, orig_src_pte))) {
-		err = -EAGAIN;
+		ret = -EAGAIN;
 		goto out;
 	}
 
 	if (pte_present(orig_src_pte)) {
 		if (is_zero_pfn(pte_pfn(orig_src_pte))) {
-			err = move_zeropage_pte(mm, dst_vma, src_vma,
+			ret = move_zeropage_pte(mm, dst_vma, src_vma,
 					       dst_addr, src_addr, dst_pte, src_pte,
 					       orig_dst_pte, orig_src_pte,
 					       dst_pmd, dst_pmdval, dst_ptl, src_ptl);
@@ -1292,14 +1362,14 @@ retry:
 			spin_lock(src_ptl);
 			if (!pte_same(orig_src_pte, ptep_get(src_pte))) {
 				spin_unlock(src_ptl);
-				err = -EAGAIN;
+				ret = -EAGAIN;
 				goto out;
 			}
 
 			folio = vm_normal_folio(src_vma, src_addr, orig_src_pte);
 			if (!folio || !PageAnonExclusive(&folio->page)) {
 				spin_unlock(src_ptl);
-				err = -EBUSY;
+				ret = -EBUSY;
 				goto out;
 			}
 
@@ -1313,7 +1383,7 @@ retry:
 			 */
 			if (!locked && folio_test_large(folio)) {
 				spin_unlock(src_ptl);
-				err = -EAGAIN;
+				ret = -EAGAIN;
 				goto out;
 			}
 
@@ -1332,7 +1402,7 @@ retry:
 			}
 
 			if (WARN_ON_ONCE(!folio_test_anon(src_folio))) {
-				err = -EBUSY;
+				ret = -EBUSY;
 				goto out;
 			}
 		}
@@ -1343,8 +1413,8 @@ retry:
 			pte_unmap(src_pte);
 			pte_unmap(dst_pte);
 			src_pte = dst_pte = NULL;
-			err = split_folio(src_folio);
-			if (err)
+			ret = split_folio(src_folio);
+			if (ret)
 				goto out;
 			/* have to reacquire the folio after it got split */
 			folio_unlock(src_folio);
@@ -1362,7 +1432,7 @@ retry:
 			src_anon_vma = folio_get_anon_vma(src_folio);
 			if (!src_anon_vma) {
 				/* page was unmapped from under us */
-				err = -EAGAIN;
+				ret = -EAGAIN;
 				goto out;
 			}
 			if (!anon_vma_trylock_write(src_anon_vma)) {
@@ -1375,10 +1445,11 @@ retry:
 			}
 		}
 
-		err = move_present_pte(mm,  dst_vma, src_vma,
-				       dst_addr, src_addr, dst_pte, src_pte,
-				       orig_dst_pte, orig_src_pte, dst_pmd,
-				       dst_pmdval, dst_ptl, src_ptl, src_folio);
+		ret = move_present_ptes(mm, dst_vma, src_vma,
+					dst_addr, src_addr, dst_pte, src_pte,
+					orig_dst_pte, orig_src_pte, dst_pmd,
+					dst_pmdval, dst_ptl, src_ptl, &src_folio,
+					len, src_anon_vma);
 	} else {
 		struct folio *folio = NULL;
 
@@ -1389,20 +1460,20 @@ retry:
 				pte_unmap(dst_pte);
 				src_pte = dst_pte = NULL;
 				migration_entry_wait(mm, src_pmd, src_addr);
-				err = -EAGAIN;
+				ret = -EAGAIN;
 			} else
-				err = -EFAULT;
+				ret = -EFAULT;
 			goto out;
 		}
 
 		if (!pte_swp_exclusive(orig_src_pte)) {
-			err = -EBUSY;
+			ret = -EBUSY;
 			goto out;
 		}
 
 		si = get_swap_device(entry);
 		if (unlikely(!si)) {
-			err = -EAGAIN;
+			ret = -EAGAIN;
 			goto out;
 		}
 		/*
@@ -1418,11 +1489,10 @@ retry:
 		 * separately to allow proper handling.
 		 */
 		if (!src_folio)
-			folio = filemap_get_folio(swap_address_space(entry),
-					swap_cache_index(entry));
-		if (!IS_ERR_OR_NULL(folio)) {
+			folio = swap_cache_get_folio(entry);
+		if (folio) {
 			if (folio_test_large(folio)) {
-				err = -EBUSY;
+				ret = -EBUSY;
 				folio_put(folio);
 				goto out;
 			}
@@ -1439,7 +1509,7 @@ retry:
 				goto retry;
 			}
 		}
-		err = move_swap_pte(mm, dst_vma, dst_addr, src_addr, dst_pte, src_pte,
+		ret = move_swap_pte(mm, dst_vma, dst_addr, src_addr, dst_pte, src_pte,
 				orig_dst_pte, orig_src_pte, dst_pmd, dst_pmdval,
 				dst_ptl, src_ptl, src_folio, si, entry);
 	}
@@ -1466,7 +1536,7 @@ out:
 	if (si)
 		put_swap_device(si);
 
-	return err;
+	return ret;
 }
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
@@ -1737,7 +1807,7 @@ ssize_t move_pages(struct userfaultfd_ctx *ctx, unsigned long dst_start,
 {
 	struct mm_struct *mm = ctx->mm;
 	struct vm_area_struct *src_vma, *dst_vma;
-	unsigned long src_addr, dst_addr;
+	unsigned long src_addr, dst_addr, src_end;
 	pmd_t *src_pmd, *dst_pmd;
 	long err = -EINVAL;
 	ssize_t moved = 0;
@@ -1780,8 +1850,8 @@ ssize_t move_pages(struct userfaultfd_ctx *ctx, unsigned long dst_start,
 	if (err)
 		goto out_unlock;
 
-	for (src_addr = src_start, dst_addr = dst_start;
-	     src_addr < src_start + len;) {
+	for (src_addr = src_start, dst_addr = dst_start, src_end = src_start + len;
+	     src_addr < src_end;) {
 		spinlock_t *ptl;
 		pmd_t dst_pmdval;
 		unsigned long step_size;
@@ -1849,6 +1919,8 @@ ssize_t move_pages(struct userfaultfd_ctx *ctx, unsigned long dst_start,
 						  dst_addr, src_addr);
 			step_size = HPAGE_PMD_SIZE;
 		} else {
+			long ret;
+
 			if (pmd_none(*src_pmd)) {
 				if (!(mode & UFFDIO_MOVE_MODE_ALLOW_SRC_HOLES)) {
 					err = -ENOENT;
@@ -1865,10 +1937,13 @@ ssize_t move_pages(struct userfaultfd_ctx *ctx, unsigned long dst_start,
 				break;
 			}
 
-			err = move_pages_pte(mm, dst_pmd, src_pmd,
-					     dst_vma, src_vma,
-					     dst_addr, src_addr, mode);
-			step_size = PAGE_SIZE;
+			ret = move_pages_ptes(mm, dst_pmd, src_pmd,
+					      dst_vma, src_vma, dst_addr,
+					      src_addr, src_end - src_addr, mode);
+			if (ret < 0)
+				err = ret;
+			else
+				step_size = ret;
 		}
 
 		cond_resched();