From: Liam R. Howlett <Liam.Howlett@oracle.com>
Date: Tue, 28 Oct 2025 19:06:36 +0000 (-0400)
Subject: mm/userfaultfd: Use uffd_info for uffd_ctx_lock_and_validate_dst()
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=ba76e00461c6986ec4f94553b08bbd46641bc2e0;p=users%2Fjedix%2Flinux-maple.git

mm/userfaultfd: Use uffd_info for uffd_ctx_lock_and_validate_dst()

uffd_info has all the necessary information for many function including
uffd_ctx_lock_and_validate_dst(), so just pass the struct around as
needed.

Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
---

diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 931b428dd7ec..9c45223e7d92 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -561,11 +561,8 @@ uffd_failed_do_unlock(struct userfaultfd_ctx *ctx, struct vm_area_struct *dst,
  */
 static inline ssize_t
 uffd_ctx_lock_and_validate_dst(struct userfaultfd_ctx *ctx,
-		struct vm_area_struct *dst_vma, unsigned long dst_start,
-		unsigned long len, uffd_flags_t flags)
+		struct uffd_info *info)
 {
-	const struct vm_uffd_ops *uffd_ops;
-
 	/*
 	 * If memory mappings are changing because of non-cooperative
 	 * operation (e.g. mremap) running in parallel, bail out and
@@ -579,30 +576,20 @@ uffd_ctx_lock_and_validate_dst(struct userfaultfd_ctx *ctx,
 	 * shmem_zero_setup is invoked in mmap for MAP_ANONYMOUS|MAP_SHARED but
 	 * it will overwrite vm_ops, so vma_is_anonymous must return false.
 	 */
-	if (WARN_ON_ONCE(vma_is_anonymous(dst_vma) &&
-	    dst_vma->vm_flags & VM_SHARED))
+	if (WARN_ON_ONCE(vma_is_anonymous(info->dst_vma) &&
+	    info->dst_vma->vm_flags & VM_SHARED))
 		return -EINVAL;
 	/*
 	 * validate 'mode' now that we know the dst_vma: don't allow
 	 * a wrprotect copy if the userfaultfd didn't register as WP.
 	 */
-	if ((flags & MFILL_ATOMIC_WP) && !(dst_vma->vm_flags & VM_UFFD_WP))
+	if (info->wp && !(info->dst_vma->vm_flags & VM_UFFD_WP))
 		return -EINVAL;
 
-	uffd_ops = vma_get_uffd_ops(dst_vma);
-	WARN_ON_ONCE(!uffd_ops || !uffd_ops->is_dst_valid);
-
-	/*
-	 * There is no default zero huge page for all huge page sizes as
-	 * supported by hugetlb.  A PMD_SIZE huge pages may exist as used
-	 * by THP.  Since we can not reliably insert a zero page, this
-	 * feature is not supported.
-	 */
-	if (!uffd_ops->zeropage &&
-	    uffd_flags_mode_is(flags, MFILL_ATOMIC_ZEROPAGE))
-		return -EINVAL;
+	WARN_ON_ONCE(!info->uffd_ops->is_dst_valid);
 
-	return uffd_ops->is_dst_valid(dst_vma, dst_start, len);
+	return info->uffd_ops->is_dst_valid(info->dst_vma, info->dst_addr,
+					    info->len);
 }
 
 ssize_t
@@ -648,7 +635,6 @@ static __always_inline ssize_t mfill_atomic(struct userfaultfd_ctx *ctx,
 	unsigned long src_addr, dst_addr;
 	long copied;
 	struct folio *folio;
-	const struct vm_uffd_ops *uffd_ops;
 	unsigned long increment;
 	struct uffd_info info = UFFD_STRUCT_INIT(dst_start, src_start, len,
 						 flags & MFILL_ATOMIC_WP);
@@ -678,23 +664,32 @@ retry:
 		goto out;
 
 	dst_vma = info.dst_vma;
-	uffd_ops = vma_get_uffd_ops(dst_vma);
-	if (WARN_ON_ONCE(!uffd_ops->increment)) {
+	info.uffd_ops = vma_get_uffd_ops(dst_vma);
+	if (WARN_ON_ONCE(!info.uffd_ops->increment)) {
 		increment = PAGE_SIZE;
 	} else {
-		increment = uffd_ops->increment(dst_vma);
+		increment = info.uffd_ops->increment(dst_vma);
 	}
 
-	err = uffd_ctx_lock_and_validate_dst(ctx, dst_vma, dst_start, len,
-					     flags);
+	err = uffd_ctx_lock_and_validate_dst(ctx, &info);
 	if (err)
 		goto out_unlock;
 
 	err = -EINVAL;
-	if (!uffd_ops->cont &&
+	if (!info.uffd_ops->cont &&
 	    uffd_flags_mode_is(flags, MFILL_ATOMIC_CONTINUE))
 		goto out_unlock;
 
+	/*
+	 * There is no default zero huge page for all huge page sizes as
+	 * supported by hugetlb.  A PMD_SIZE huge pages may exist as used
+	 * by THP.  Since we can not reliably insert a zero page, this
+	 * feature is not supported.
+	 */
+	if (!info.uffd_ops->zeropage &&
+	    uffd_flags_mode_is(flags, MFILL_ATOMIC_ZEROPAGE))
+		goto out_unlock;
+
 	info.increment = increment;
 	while (src_addr < src_start + len) {
 		VM_WARN_ON_ONCE(dst_addr >= dst_start + len);
@@ -704,13 +699,14 @@ retry:
 		 * tables under us; pte_offset_map_lock() will deal with that.
 		 */
 		if (uffd_flags_mode_is(flags, MFILL_ATOMIC_POISON)) {
-			err = uffd_ops->poison(dst_vma, dst_addr, increment);
+			err = info.uffd_ops->poison(dst_vma, dst_addr,
+						    increment);
 		} else if (uffd_flags_mode_is(flags, MFILL_ATOMIC_CONTINUE)) {
-			err = uffd_ops->cont(dst_vma, dst_addr,
+			err = info.uffd_ops->cont(dst_vma, dst_addr,
 					     flags & MFILL_ATOMIC_WP,
 					     increment);
 		} else if (uffd_flags_mode_is(flags, MFILL_ATOMIC_COPY)) {
-			err = uffd_ops->copy(dst_vma, dst_addr, src_addr,
+			err = info.uffd_ops->copy(dst_vma, dst_addr, src_addr,
 					     flags & MFILL_ATOMIC_WP,
 					     &folio, increment);
 			/*
@@ -725,14 +721,14 @@ retry:
 			 * the radix tree.
 			 */
 		} else {
-			err = uffd_ops->zeropage(dst_vma, dst_addr);
+			err = info.uffd_ops->zeropage(dst_vma, dst_addr);
 		}
 
 		cond_resched();
 
 		if (unlikely(err == -ENOENT)) {
-			err = uffd_ops->failed_do_unlock(ctx, dst_vma, folio,
-							 src_addr);
+			err = info.uffd_ops->failed_do_unlock(ctx, dst_vma,
+							      folio, src_addr);
 			if (unlikely(err))
 				goto out;