1 files changed, 125 insertions, 4 deletions

diff --git a/mm/madvise.c b/mm/madvise.c
index 4b9c5509990c..413bbc6e40a0 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -18,6 +18,7 @@
 #include <linux/fadvise.h>
 #include <linux/sched.h>
 #include <linux/sched/mm.h>
+#include <linux/string.h>
 #include <linux/uio.h>
 #include <linux/ksm.h>
 #include <linux/fs.h>
@@ -62,19 +63,84 @@ static int madvise_need_mmap_write(int behavior)
 	}
 }
 
+#ifdef CONFIG_ANON_VMA_NAME
+static inline bool has_vma_anon_name(struct vm_area_struct *vma)
+{
+	return !vma->vm_file && vma->anon_name;
+}
+
+const char *vma_anon_name(struct vm_area_struct *vma)
+{
+	if (!has_vma_anon_name(vma))
+		return NULL;
+
+	mmap_assert_locked(vma->vm_mm);
+
+	return vma->anon_name;
+}
+
+void dup_vma_anon_name(struct vm_area_struct *orig_vma,
+		       struct vm_area_struct *new_vma)
+{
+	if (!has_vma_anon_name(orig_vma))
+		return;
+
+	new_vma->anon_name = kstrdup(orig_vma->anon_name, GFP_KERNEL);
+}
+
+void free_vma_anon_name(struct vm_area_struct *vma)
+{
+	if (!has_vma_anon_name(vma))
+		return;
+
+	kfree(vma->anon_name);
+	vma->anon_name = NULL;
+}
+
+/* mmap_lock should be write-locked */
+static int replace_vma_anon_name(struct vm_area_struct *vma, const char *name)
+{
+	if (!name) {
+		free_vma_anon_name(vma);
+		return 0;
+	}
+
+	if (vma->anon_name) {
+		/* Same name, nothing to do here */
+		if (!strcmp(name, vma->anon_name))
+			return 0;
+
+		free_vma_anon_name(vma);
+	}
+	vma->anon_name = kstrdup(name, GFP_KERNEL);
+	if (!vma->anon_name)
+		return -ENOMEM;
+
+	return 0;
+}
+#else /* CONFIG_ANON_VMA_NAME */
+static int replace_vma_anon_name(struct vm_area_struct *vma, const char *name)
+{
+	if (name)
+		return -EINVAL;
+
+	return 0;
+}
+#endif /* CONFIG_ANON_VMA_NAME */
 /*
  * Update the vm_flags on region of a vma, splitting it or merging it as
  * necessary.  Must be called with mmap_sem held for writing;
  */
 static int madvise_update_vma(struct vm_area_struct *vma,
 			      struct vm_area_struct **prev, unsigned long start,
-			      unsigned long end, unsigned long new_flags)
+			      unsigned long end, unsigned long new_flags,
+			      const char *name)
 {
 	struct mm_struct *mm = vma->vm_mm;
 	int error;
 	pgoff_t pgoff;
 
-	if (new_flags == vma->vm_flags) {
+	if (new_flags == vma->vm_flags && is_same_vma_anon_name(vma, name)) {
 		*prev = vma;
 		return 0;
 	}
@@ -82,7 +148,7 @@ static int madvise_update_vma(struct vm_area_struct *vma,
 	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
 	*prev = vma_merge(mm, *prev, start, end, new_flags, vma->anon_vma,
 			  vma->vm_file, pgoff, vma_policy(vma),
-			  vma->vm_userfaultfd_ctx);
+			  vma->vm_userfaultfd_ctx, name);
 	if (*prev) {
 		vma = *prev;
 		goto success;
@@ -111,6 +177,11 @@ success:
 	 * vm_flags is protected by the mmap_lock held in write mode.
 	 */
 	vma->vm_flags = new_flags;
+	if (!vma->vm_file) {
+		error = replace_vma_anon_name(vma, name);
+		if (error)
+			return error;
+	}
 
 	return 0;
 }
@@ -938,7 +1009,8 @@ static int madvise_vma_behavior(struct vm_area_struct *vma,
 		break;
 	}
 
-	error = madvise_update_vma(vma, prev, start, end, new_flags);
+	error = madvise_update_vma(vma, prev, start, end, new_flags,
+				   vma_anon_name(vma));
 
 out:
 	/*
@@ -1118,6 +1190,55 @@ int madvise_walk_vmas(struct mm_struct *mm, unsigned long start,
 	return unmapped_error;
 }
 
+#ifdef CONFIG_ANON_VMA_NAME
+static int madvise_vma_anon_name(struct vm_area_struct *vma,
+				 struct vm_area_struct **prev,
+				 unsigned long start, unsigned long end,
+				 unsigned long name)
+{
+	int error;
+
+	/* Only anonymous mappings can be named */
+	if (vma->vm_file)
+		return -EBADF;
+
+	error = madvise_update_vma(vma, prev, start, end, vma->vm_flags,
+				   (const char *)name);
+
+	/*
+	 * madvise() returns EAGAIN if kernel resources, such as
+	 * slab, are temporarily unavailable.
+	 */
+	if (error == -ENOMEM)
+		error = -EAGAIN;
+	return error;
+}
+
+int madvise_set_anon_name(struct mm_struct *mm, unsigned long start,
+			  unsigned long len_in, const char *name)
+{
+	unsigned long end;
+	unsigned long len;
+
+	if (start & ~PAGE_MASK)
+		return -EINVAL;
+	len = (len_in + ~PAGE_MASK) & PAGE_MASK;
+
+	/* Check to see whether len was rounded up from small -ve to zero */
+	if (len_in && !len)
+		return -EINVAL;
+
+	end = start + len;
+	if (end < start)
+		return -EINVAL;
+
+	if (end == start)
+		return 0;
+
+	return madvise_walk_vmas(mm, start, end, (unsigned long)name,
+				 madvise_vma_anon_name);
+}
+#endif /* CONFIG_ANON_VMA_NAME */
 /*
  * The madvise(2) system call.
  *