Revert "ANDROID: mm: add a field to store names for private anonymous memory"

This reverts commit d5cd22fded2b47e46ac02744c118d25070d5bc09.

12 files changed, 28 insertions, 280 deletions

diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst
index 6016b0b60321..533c79e8d2cd 100644
--- a/Documentation/filesystems/proc.rst
+++ b/Documentation/filesystems/proc.rst
@@ -429,8 +429,6 @@ is not associated with a file:
  [stack]                    the stack of the main process
  [vdso]                     the "virtual dynamic shared object",
                             the kernel system call handler
- [anon:<name>]              an anonymous mapping that has been
-                            named by userspace
  =======                    ====================================
 
  or if empty, the mapping is anonymous.
@@ -464,7 +462,6 @@ Memory Area, or VMA) there is a series of lines such as the following::
     Locked:                0 kB
     THPeligible:           0
     VmFlags: rd ex mr mw me dw
-    Name:           name from userspace
 
 The first of these lines shows the same information as is displayed for the
 mapping in /proc/PID/maps.  Following lines show the size of the mapping
@@ -557,9 +554,6 @@ be vanished or the reverse -- new added. Interpretation of their meaning
 might change in future as well. So each consumer of these flags has to
 follow each specific kernel version for the exact semantic.
 
-The "Name" field will only be present on a mapping that has been named by
-userspace, and will show the name passed in by userspace.
-
 This file is only present if the CONFIG_MMU kernel configuration option is
 enabled.
 
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index b5b31f8dd887..5066b0251ed8 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -123,56 +123,6 @@ static void release_task_mempolicy(struct proc_maps_private *priv)
 }
 #endif
 
-static void seq_print_vma_name(struct seq_file *m, struct vm_area_struct *vma)
-{
-	const char __user *name = vma_get_anon_name(vma);
-	struct mm_struct *mm = vma->vm_mm;
-
-	unsigned long page_start_vaddr;
-	unsigned long page_offset;
-	unsigned long num_pages;
-	unsigned long max_len = NAME_MAX;
-	int i;
-
-	page_start_vaddr = (unsigned long)name & PAGE_MASK;
-	page_offset = (unsigned long)name - page_start_vaddr;
-	num_pages = DIV_ROUND_UP(page_offset + max_len, PAGE_SIZE);
-
-	seq_puts(m, "[anon:");
-
-	for (i = 0; i < num_pages; i++) {
-		int len;
-		int write_len;
-		const char *kaddr;
-		long pages_pinned;
-		struct page *page;
-
-		pages_pinned = get_user_pages_remote(current, mm,
-				page_start_vaddr, 1, 0, &page, NULL, NULL);
-		if (pages_pinned < 1) {
-			seq_puts(m, "<fault>]");
-			return;
-		}
-
-		kaddr = (const char *)kmap(page);
-		len = min(max_len, PAGE_SIZE - page_offset);
-		write_len = strnlen(kaddr + page_offset, len);
-		seq_write(m, kaddr + page_offset, write_len);
-		kunmap(page);
-		put_page(page);
-
-		/* if strnlen hit a null terminator then we're done */
-		if (write_len != len)
-			break;
-
-		max_len -= len;
-		page_offset = 0;
-		page_start_vaddr += PAGE_SIZE;
-	}
-
-	seq_putc(m, ']');
-}
-
 static void *m_start(struct seq_file *m, loff_t *ppos)
 {
 	struct proc_maps_private *priv = m->private;
@@ -369,15 +319,8 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma)
 			goto done;
 		}
 
-		if (is_stack(vma)) {
+		if (is_stack(vma))
 			name = "[stack]";
-			goto done;
-		}
-
-		if (vma_get_anon_name(vma)) {
-			seq_pad(m, ' ');
-			seq_print_vma_name(m, vma);
-		}
 	}
 
 done:
@@ -865,11 +808,6 @@ static int show_smap(struct seq_file *m, void *v)
 	smap_gather_stats(vma, &mss);
 
 	show_map_vma(m, vma);
-	if (vma_get_anon_name(vma)) {
-		seq_puts(m, "Name:           ");
-		seq_print_vma_name(m, vma);
-		seq_putc(m, '\n');
-	}
 
 	SEQ_PUT_DEC("Size:           ", vma->vm_end - vma->vm_start);
 	SEQ_PUT_DEC(" kB\nKernelPageSize: ", vma_kernel_pagesize(vma));
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 2b6233baf7c3..0e4a3837da52 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -874,8 +874,7 @@ static int userfaultfd_release(struct inode *inode, struct file *file)
 					 new_flags, vma->anon_vma,
 					 vma->vm_file, vma->vm_pgoff,
 					 vma_policy(vma),
-					 NULL_VM_UFFD_CTX,
-					 vma_get_anon_name(vma));
+					 NULL_VM_UFFD_CTX);
 			if (prev)
 				vma = prev;
 			else
@@ -1426,8 +1425,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
 		prev = vma_merge(mm, prev, start, vma_end, new_flags,
 				 vma->anon_vma, vma->vm_file, vma->vm_pgoff,
 				 vma_policy(vma),
-				 ((struct vm_userfaultfd_ctx){ ctx }),
-				 vma_get_anon_name(vma));
+				 ((struct vm_userfaultfd_ctx){ ctx }));
 		if (prev) {
 			vma = prev;
 			goto next;
@@ -1599,8 +1597,7 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
 		prev = vma_merge(mm, prev, start, vma_end, new_flags,
 				 vma->anon_vma, vma->vm_file, vma->vm_pgoff,
 				 vma_policy(vma),
-				 NULL_VM_UFFD_CTX,
-				 vma_get_anon_name(vma));
+				 NULL_VM_UFFD_CTX);
 		if (prev) {
 			vma = prev;
 			goto next;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index a0f1e361f31d..ca6e6a81576b 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2489,7 +2489,7 @@ static inline int vma_adjust(struct vm_area_struct *vma, unsigned long start,
 extern struct vm_area_struct *vma_merge(struct mm_struct *,
 	struct vm_area_struct *prev, unsigned long addr, unsigned long end,
 	unsigned long vm_flags, struct anon_vma *, struct file *, pgoff_t,
-	struct mempolicy *, struct vm_userfaultfd_ctx, const char __user *);
+	struct mempolicy *, struct vm_userfaultfd_ctx);
 extern struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *);
 extern int __split_vma(struct mm_struct *, struct vm_area_struct *,
 	unsigned long addr, int new_below);
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 9103b83eb1b0..496c3ff97cce 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -336,18 +336,11 @@ struct vm_area_struct {
 	/*
 	 * For areas with an address space and backing store,
 	 * linkage into the address_space->i_mmap interval tree.
-	 *
-	 * For private anonymous mappings, a pointer to a null terminated string
-	 * in the user process containing the name given to the vma, or NULL
-	 * if unnamed.
 	 */
-	union {
-		struct {
-			struct rb_node rb;
-			unsigned long rb_subtree_last;
-		} shared;
-		const char __user *anon_name;
-	};
+	struct {
+		struct rb_node rb;
+		unsigned long rb_subtree_last;
+	} shared;
 
 	/*
 	 * A file's MAP_PRIVATE vma can be in both i_mmap tree and anon_vma
@@ -779,13 +772,4 @@ typedef struct {
 	unsigned long val;
 } swp_entry_t;
 
-/* Return the name for an anonymous mapping or NULL for a file-backed mapping */
-static inline const char __user *vma_get_anon_name(struct vm_area_struct *vma)
-{
-	if (vma->vm_file)
-		return NULL;
-
-	return vma->anon_name;
-}
-
 #endif /* _LINUX_MM_TYPES_H */
diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h
index 10773270f67b..07b4f8131e36 100644
--- a/include/uapi/linux/prctl.h
+++ b/include/uapi/linux/prctl.h
@@ -238,7 +238,4 @@ struct prctl_mm_map {
 #define PR_SET_IO_FLUSHER		57
 #define PR_GET_IO_FLUSHER		58
 
-#define PR_SET_VMA		0x53564d41
-# define PR_SET_VMA_ANON_NAME		0
-
 #endif /* _LINUX_PRCTL_H */
diff --git a/kernel/sys.c b/kernel/sys.c
index a29a9e240ff2..ab6c409b1159 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -42,8 +42,6 @@
 #include <linux/syscore_ops.h>
 #include <linux/version.h>
 #include <linux/ctype.h>
-#include <linux/mm.h>
-#include <linux/mempolicy.h>
 
 #include <linux/compat.h>
 #include <linux/syscalls.h>
@@ -2280,153 +2278,6 @@ int __weak arch_prctl_spec_ctrl_set(struct task_struct *t, unsigned long which,
 	return -EINVAL;
 }
 
-#ifdef CONFIG_MMU
-static int prctl_update_vma_anon_name(struct vm_area_struct *vma,
-		struct vm_area_struct **prev,
-		unsigned long start, unsigned long end,
-		const char __user *name_addr)
-{
-	struct mm_struct *mm = vma->vm_mm;
-	int error = 0;
-	pgoff_t pgoff;
-
-	if (name_addr == vma_get_anon_name(vma)) {
-		*prev = vma;
-		goto out;
-	}
-
-	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
-	*prev = vma_merge(mm, *prev, start, end, vma->vm_flags, vma->anon_vma,
-				vma->vm_file, pgoff, vma_policy(vma),
-				vma->vm_userfaultfd_ctx, name_addr);
-	if (*prev) {
-		vma = *prev;
-		goto success;
-	}
-
-	*prev = vma;
-
-	if (start != vma->vm_start) {
-		error = split_vma(mm, vma, start, 1);
-		if (error)
-			goto out;
-	}
-
-	if (end != vma->vm_end) {
-		error = split_vma(mm, vma, end, 0);
-		if (error)
-			goto out;
-	}
-
-success:
-	if (!vma->vm_file)
-		vma->anon_name = name_addr;
-
-out:
-	if (error == -ENOMEM)
-		error = -EAGAIN;
-	return error;
-}
-
-static int prctl_set_vma_anon_name(unsigned long start, unsigned long end,
-			unsigned long arg)
-{
-	unsigned long tmp;
-	struct vm_area_struct *vma, *prev;
-	int unmapped_error = 0;
-	int error = -EINVAL;
-
-	/*
-	 * If the interval [start,end) covers some unmapped address
-	 * ranges, just ignore them, but return -ENOMEM at the end.
-	 * - this matches the handling in madvise.
-	 */
-	vma = find_vma_prev(current->mm, start, &prev);
-	if (vma && start > vma->vm_start)
-		prev = vma;
-
-	for (;;) {
-		/* Still start < end. */
-		error = -ENOMEM;
-		if (!vma)
-			return error;
-
-		/* Here start < (end|vma->vm_end). */
-		if (start < vma->vm_start) {
-			unmapped_error = -ENOMEM;
-			start = vma->vm_start;
-			if (start >= end)
-				return error;
-		}
-
-		/* Here vma->vm_start <= start < (end|vma->vm_end) */
-		tmp = vma->vm_end;
-		if (end < tmp)
-			tmp = end;
-
-		/* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
-		error = prctl_update_vma_anon_name(vma, &prev, start, tmp,
-				(const char __user *)arg);
-		if (error)
-			return error;
-		start = tmp;
-		if (prev && start < prev->vm_end)
-			start = prev->vm_end;
-		error = unmapped_error;
-		if (start >= end)
-			return error;
-		if (prev)
-			vma = prev->vm_next;
-		else	/* madvise_remove dropped mmap_sem */
-			vma = find_vma(current->mm, start);
-	}
-}
-
-static int prctl_set_vma(unsigned long opt, unsigned long start,
-		unsigned long len_in, unsigned long arg)
-{
-	struct mm_struct *mm = current->mm;
-	int error;
-	unsigned long len;
-	unsigned long end;
-
-	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;
-
-	mmap_write_lock(mm);
-
-	switch (opt) {
-	case PR_SET_VMA_ANON_NAME:
-		error = prctl_set_vma_anon_name(start, end, arg);
-		break;
-	default:
-		error = -EINVAL;
-	}
-
-	mmap_write_unlock(mm);
-
-	return error;
-}
-#else /* CONFIG_MMU */
-static int prctl_set_vma(unsigned long opt, unsigned long start,
-		unsigned long len_in, unsigned long arg)
-{
-	return -EINVAL;
-}
-#endif
-
 #define PR_IO_FLUSHER (PF_MEMALLOC_NOIO | PF_LOCAL_THROTTLE)
 
 SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
@@ -2641,9 +2492,6 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
 			return -EINVAL;
 		error = arch_prctl_spec_ctrl_set(me, arg2, arg3);
 		break;
-	case PR_SET_VMA:
-		error = prctl_set_vma(arg2, arg3, arg4, arg5);
-		break;
 	case PR_PAC_RESET_KEYS:
 		if (arg3 || arg4 || arg5)
 			return -EINVAL;
diff --git a/mm/madvise.c b/mm/madvise.c
index 3fd89037f472..dd1d43cf026d 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -135,7 +135,7 @@ static long madvise_behavior(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_get_anon_name(vma));
+			  vma->vm_userfaultfd_ctx);
 	if (*prev) {
 		vma = *prev;
 		goto success;
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 133ec4a89faf..eddbe4e56c73 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -829,8 +829,7 @@ static int mbind_range(struct mm_struct *mm, unsigned long start,
 			((vmstart - vma->vm_start) >> PAGE_SHIFT);
 		prev = vma_merge(mm, prev, vmstart, vmend, vma->vm_flags,
 				 vma->anon_vma, vma->vm_file, pgoff,
-				 new_pol, vma->vm_userfaultfd_ctx,
-				 vma_get_anon_name(vma));
+				 new_pol, vma->vm_userfaultfd_ctx);
 		if (prev) {
 			vma = prev;
 			next = vma->vm_next;
diff --git a/mm/mlock.c b/mm/mlock.c
index b845a66d421b..93ca2bf30b4f 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -534,7 +534,7 @@ static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev,
 	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
 	*prev = vma_merge(mm, *prev, start, end, newflags, vma->anon_vma,
 			  vma->vm_file, pgoff, vma_policy(vma),
-			  vma->vm_userfaultfd_ctx, vma_get_anon_name(vma));
+			  vma->vm_userfaultfd_ctx);
 	if (*prev) {
 		vma = *prev;
 		goto success;
diff --git a/mm/mmap.c b/mm/mmap.c
index 2260a9ad9f78..40248d84ad5f 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -987,8 +987,7 @@ again:
  */
 static inline int is_mergeable_vma(struct vm_area_struct *vma,
 				struct file *file, unsigned long vm_flags,
-				struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
-				const char __user *anon_name)
+				struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
 {
 	/*
 	 * VM_SOFTDIRTY should not prevent from VMA merging, if we
@@ -1006,8 +1005,6 @@ static inline int is_mergeable_vma(struct vm_area_struct *vma,
 		return 0;
 	if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx))
 		return 0;
-	if (vma_get_anon_name(vma) != anon_name)
-		return 0;
 	return 1;
 }
 
@@ -1040,10 +1037,9 @@ static int
 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
 		     struct anon_vma *anon_vma, struct file *file,
 		     pgoff_t vm_pgoff,
-		     struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
-		     const char __user *anon_name)
+		     struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
 {
-	if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name) &&
+	if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
 	    is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
 		if (vma->vm_pgoff == vm_pgoff)
 			return 1;
@@ -1062,10 +1058,9 @@ static int
 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
 		    struct anon_vma *anon_vma, struct file *file,
 		    pgoff_t vm_pgoff,
-		    struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
-		    const char __user *anon_name)
+		    struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
 {
-	if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name) &&
+	if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
 	    is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
 		pgoff_t vm_pglen;
 		vm_pglen = vma_pages(vma);
@@ -1076,9 +1071,9 @@ can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
 }
 
 /*
- * Given a mapping request (addr,end,vm_flags,file,pgoff,anon_name),
- * figure out whether that can be merged with its predecessor or its
- * successor.  Or both (it neatly fills a hole).
+ * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
+ * whether that can be merged with its predecessor or its successor.
+ * Or both (it neatly fills a hole).
  *
  * In most cases - when called for mmap, brk or mremap - [addr,end) is
  * certain not to be mapped by the time vma_merge is called; but when
@@ -1123,8 +1118,7 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm,
 			unsigned long end, unsigned long vm_flags,
 			struct anon_vma *anon_vma, struct file *file,
 			pgoff_t pgoff, struct mempolicy *policy,
-			struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
-			const char __user *anon_name)
+			struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
 {
 	pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
 	struct vm_area_struct *area, *next;
@@ -1157,8 +1151,7 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm,
 			mpol_equal(vma_policy(prev), policy) &&
 			can_vma_merge_after(prev, vm_flags,
 					    anon_vma, file, pgoff,
-					    vm_userfaultfd_ctx,
-					    anon_name)) {
+					    vm_userfaultfd_ctx)) {
 		/*
 		 * OK, it can.  Can we now merge in the successor as well?
 		 */
@@ -1167,8 +1160,7 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm,
 				can_vma_merge_before(next, vm_flags,
 						     anon_vma, file,
 						     pgoff+pglen,
-						     vm_userfaultfd_ctx,
-						     anon_name) &&
+						     vm_userfaultfd_ctx) &&
 				is_mergeable_anon_vma(prev->anon_vma,
 						      next->anon_vma, NULL)) {
 							/* cases 1, 6 */
@@ -1191,8 +1183,7 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm,
 			mpol_equal(policy, vma_policy(next)) &&
 			can_vma_merge_before(next, vm_flags,
 					     anon_vma, file, pgoff+pglen,
-					     vm_userfaultfd_ctx,
-					     anon_name)) {
+					     vm_userfaultfd_ctx)) {
 		if (prev && addr < prev->vm_end)	/* case 4 */
 			err = __vma_adjust(prev, prev->vm_start,
 					 addr, prev->vm_pgoff, NULL, next);
@@ -1740,7 +1731,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 	 * Can we just expand an old mapping?
 	 */
 	vma = vma_merge(mm, prev, addr, addr + len, vm_flags,
-			NULL, file, pgoff, NULL, NULL_VM_UFFD_CTX, NULL);
+			NULL, file, pgoff, NULL, NULL_VM_UFFD_CTX);
 	if (vma)
 		goto out;
 
@@ -3072,7 +3063,7 @@ static int do_brk_flags(unsigned long addr, unsigned long len, unsigned long fla
 
 	/* Can we just expand an old private anonymous mapping? */
 	vma = vma_merge(mm, prev, addr, addr + len, flags,
-			NULL, NULL, pgoff, NULL, NULL_VM_UFFD_CTX, NULL);
+			NULL, NULL, pgoff, NULL, NULL_VM_UFFD_CTX);
 	if (vma)
 		goto out;
 
@@ -3271,7 +3262,7 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
 		return NULL;	/* should never get here */
 	new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
 			    vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
-			    vma->vm_userfaultfd_ctx, vma_get_anon_name(vma));
+			    vma->vm_userfaultfd_ctx);
 	if (new_vma) {
 		/*
 		 * Source vma may have been merged into new_vma
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 97529ba11a3b..ce8b8a5eacbb 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -454,7 +454,7 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
 	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
 	*pprev = vma_merge(mm, *pprev, start, end, newflags,
 			   vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
-			   vma->vm_userfaultfd_ctx, vma_get_anon_name(vma));
+			   vma->vm_userfaultfd_ctx);
 	if (*pprev) {
 		vma = *pprev;
 		VM_WARN_ON((vma->vm_flags ^ newflags) & ~VM_SOFTDIRTY);