1 files changed, 139 insertions, 103 deletions

diff --git a/mm/shmem.c b/mm/shmem.c
index b9081b817d28..3f194c9842a8 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -66,7 +66,7 @@ static struct vfsmount *shm_mnt __ro_after_init;
 #include <linux/falloc.h>
 #include <linux/splice.h>
 #include <linux/security.h>
-#include <linux/swapops.h>
+#include <linux/leafops.h>
 #include <linux/mempolicy.h>
 #include <linux/namei.h>
 #include <linux/ctype.h>
@@ -131,8 +131,7 @@ struct shmem_options {
 #define SHMEM_SEEN_INODES 2
 #define SHMEM_SEEN_HUGE 4
 #define SHMEM_SEEN_INUMS 8
-#define SHMEM_SEEN_NOSWAP 16
-#define SHMEM_SEEN_QUOTA 32
+#define SHMEM_SEEN_QUOTA 16
 };
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
@@ -175,20 +174,20 @@ static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
  */
 static inline int shmem_acct_size(unsigned long flags, loff_t size)
 {
-	return (flags & VM_NORESERVE) ?
+	return (flags & SHMEM_F_NORESERVE) ?
 		0 : security_vm_enough_memory_mm(current->mm, VM_ACCT(size));
 }
 
 static inline void shmem_unacct_size(unsigned long flags, loff_t size)
 {
-	if (!(flags & VM_NORESERVE))
+	if (!(flags & SHMEM_F_NORESERVE))
 		vm_unacct_memory(VM_ACCT(size));
 }
 
 static inline int shmem_reacct_size(unsigned long flags,
 		loff_t oldsize, loff_t newsize)
 {
-	if (!(flags & VM_NORESERVE)) {
+	if (!(flags & SHMEM_F_NORESERVE)) {
 		if (VM_ACCT(newsize) > VM_ACCT(oldsize))
 			return security_vm_enough_memory_mm(current->mm,
 					VM_ACCT(newsize) - VM_ACCT(oldsize));
@@ -206,7 +205,7 @@ static inline int shmem_reacct_size(unsigned long flags,
  */
 static inline int shmem_acct_blocks(unsigned long flags, long pages)
 {
-	if (!(flags & VM_NORESERVE))
+	if (!(flags & SHMEM_F_NORESERVE))
 		return 0;
 
 	return security_vm_enough_memory_mm(current->mm,
@@ -215,11 +214,11 @@ static inline int shmem_acct_blocks(unsigned long flags, long pages)
 
 static inline void shmem_unacct_blocks(unsigned long flags, long pages)
 {
-	if (flags & VM_NORESERVE)
+	if (flags & SHMEM_F_NORESERVE)
 		vm_unacct_memory(pages * VM_ACCT(PAGE_SIZE));
 }
 
-static int shmem_inode_acct_blocks(struct inode *inode, long pages)
+int shmem_inode_acct_blocks(struct inode *inode, long pages)
 {
 	struct shmem_inode_info *info = SHMEM_I(inode);
 	struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
@@ -435,7 +434,7 @@ static void shmem_free_inode(struct super_block *sb, size_t freed_ispace)
  *
  * Return: true if swapped was incremented from 0, for shmem_writeout().
  */
-static bool shmem_recalc_inode(struct inode *inode, long alloced, long swapped)
+bool shmem_recalc_inode(struct inode *inode, long alloced, long swapped)
 {
 	struct shmem_inode_info *info = SHMEM_I(inode);
 	bool first_swapped = false;
@@ -570,8 +569,37 @@ static int shmem_confirm_swap(struct address_space *mapping, pgoff_t index,
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 /* ifdef here to avoid bloating shmem.o when not necessary */
 
-static int shmem_huge __read_mostly = SHMEM_HUGE_NEVER;
-static int tmpfs_huge __read_mostly = SHMEM_HUGE_NEVER;
+#if defined(CONFIG_TRANSPARENT_HUGEPAGE_SHMEM_HUGE_NEVER)
+#define SHMEM_HUGE_DEFAULT SHMEM_HUGE_NEVER
+#elif defined(CONFIG_TRANSPARENT_HUGEPAGE_SHMEM_HUGE_ALWAYS)
+#define SHMEM_HUGE_DEFAULT SHMEM_HUGE_ALWAYS
+#elif defined(CONFIG_TRANSPARENT_HUGEPAGE_SHMEM_HUGE_WITHIN_SIZE)
+#define SHMEM_HUGE_DEFAULT SHMEM_HUGE_WITHIN_SIZE
+#elif defined(CONFIG_TRANSPARENT_HUGEPAGE_SHMEM_HUGE_ADVISE)
+#define SHMEM_HUGE_DEFAULT SHMEM_HUGE_ADVISE
+#else
+#define SHMEM_HUGE_DEFAULT SHMEM_HUGE_NEVER
+#endif
+
+static int shmem_huge __read_mostly = SHMEM_HUGE_DEFAULT;
+
+#undef SHMEM_HUGE_DEFAULT
+
+#if defined(CONFIG_TRANSPARENT_HUGEPAGE_TMPFS_HUGE_NEVER)
+#define TMPFS_HUGE_DEFAULT SHMEM_HUGE_NEVER
+#elif defined(CONFIG_TRANSPARENT_HUGEPAGE_TMPFS_HUGE_ALWAYS)
+#define TMPFS_HUGE_DEFAULT SHMEM_HUGE_ALWAYS
+#elif defined(CONFIG_TRANSPARENT_HUGEPAGE_TMPFS_HUGE_WITHIN_SIZE)
+#define TMPFS_HUGE_DEFAULT SHMEM_HUGE_WITHIN_SIZE
+#elif defined(CONFIG_TRANSPARENT_HUGEPAGE_TMPFS_HUGE_ADVISE)
+#define TMPFS_HUGE_DEFAULT SHMEM_HUGE_ADVISE
+#else
+#define TMPFS_HUGE_DEFAULT SHMEM_HUGE_NEVER
+#endif
+
+static int tmpfs_huge __read_mostly = TMPFS_HUGE_DEFAULT;
+
+#undef TMPFS_HUGE_DEFAULT
 
 static unsigned int shmem_get_orders_within_size(struct inode *inode,
 		unsigned long within_size_orders, pgoff_t index,
@@ -616,34 +644,23 @@ static unsigned int shmem_huge_global_enabled(struct inode *inode, pgoff_t index
 	 * the mTHP interface, so we still use PMD-sized huge order to
 	 * check whether global control is enabled.
 	 *
-	 * For tmpfs mmap()'s huge order, we still use PMD-sized order to
-	 * allocate huge pages due to lack of a write size hint.
-	 *
 	 * For tmpfs with 'huge=always' or 'huge=within_size' mount option,
 	 * we will always try PMD-sized order first. If that failed, it will
 	 * fall back to small large folios.
 	 */
 	switch (SHMEM_SB(inode->i_sb)->huge) {
 	case SHMEM_HUGE_ALWAYS:
-		if (vma)
-			return maybe_pmd_order;
-
 		return THP_ORDERS_ALL_FILE_DEFAULT;
 	case SHMEM_HUGE_WITHIN_SIZE:
-		if (vma)
-			within_size_orders = maybe_pmd_order;
-		else
-			within_size_orders = THP_ORDERS_ALL_FILE_DEFAULT;
-
-		within_size_orders = shmem_get_orders_within_size(inode, within_size_orders,
-								  index, write_end);
+		within_size_orders = shmem_get_orders_within_size(inode,
+				THP_ORDERS_ALL_FILE_DEFAULT, index, write_end);
 		if (within_size_orders > 0)
 			return within_size_orders;
 
 		fallthrough;
 	case SHMEM_HUGE_ADVISE:
 		if (vm_flags & VM_HUGEPAGE)
-			return maybe_pmd_order;
+			return THP_ORDERS_ALL_FILE_DEFAULT;
 		fallthrough;
 	default:
 		return 0;
@@ -853,17 +870,17 @@ static unsigned int shmem_huge_global_enabled(struct inode *inode, pgoff_t index
 static void shmem_update_stats(struct folio *folio, int nr_pages)
 {
 	if (folio_test_pmd_mappable(folio))
-		__lruvec_stat_mod_folio(folio, NR_SHMEM_THPS, nr_pages);
-	__lruvec_stat_mod_folio(folio, NR_FILE_PAGES, nr_pages);
-	__lruvec_stat_mod_folio(folio, NR_SHMEM, nr_pages);
+		lruvec_stat_mod_folio(folio, NR_SHMEM_THPS, nr_pages);
+	lruvec_stat_mod_folio(folio, NR_FILE_PAGES, nr_pages);
+	lruvec_stat_mod_folio(folio, NR_SHMEM, nr_pages);
 }
 
 /*
  * Somewhat like filemap_add_folio, but error if expected item has gone.
  */
-static int shmem_add_to_page_cache(struct folio *folio,
-				   struct address_space *mapping,
-				   pgoff_t index, void *expected, gfp_t gfp)
+int shmem_add_to_page_cache(struct folio *folio,
+			    struct address_space *mapping,
+			    pgoff_t index, void *expected, gfp_t gfp)
 {
 	XA_STATE_ORDER(xas, &mapping->i_pages, index, folio_order(folio));
 	unsigned long nr = folio_nr_pages(folio);
@@ -1076,7 +1093,7 @@ static struct folio *shmem_get_partial_folio(struct inode *inode, pgoff_t index)
  * Remove range of pages and swap entries from page cache, and free them.
  * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate.
  */
-static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
+static void shmem_undo_range(struct inode *inode, loff_t lstart, uoff_t lend,
 								 bool unfalloc)
 {
 	struct address_space *mapping = inode->i_mapping;
@@ -1133,7 +1150,7 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
 	same_folio = (lstart >> PAGE_SHIFT) == (lend >> PAGE_SHIFT);
 	folio = shmem_get_partial_folio(inode, lstart >> PAGE_SHIFT);
 	if (folio) {
-		same_folio = lend < folio_pos(folio) + folio_size(folio);
+		same_folio = lend < folio_next_pos(folio);
 		folio_mark_dirty(folio);
 		if (!truncate_inode_partial_folio(folio, lstart, lend)) {
 			start = folio_next_index(folio);
@@ -1227,7 +1244,7 @@ whole_folios:
 	shmem_recalc_inode(inode, 0, -nr_swaps_freed);
 }
 
-void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
+void shmem_truncate_range(struct inode *inode, loff_t lstart, uoff_t lend)
 {
 	shmem_undo_range(inode, lstart, lend, false);
 	inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
@@ -1297,6 +1314,8 @@ static int shmem_setattr(struct mnt_idmap *idmap,
 			return -EPERM;
 
 		if (newsize != oldsize) {
+			if (info->flags & SHMEM_F_MAPPING_FROZEN)
+				return -EPERM;
 			error = shmem_reacct_size(SHMEM_I(inode)->flags,
 					oldsize, newsize);
 			if (error)
@@ -1551,7 +1570,7 @@ int shmem_writeout(struct folio *folio, struct swap_iocb **plug,
 	int nr_pages;
 	bool split = false;
 
-	if ((info->flags & VM_LOCKED) || sbinfo->noswap)
+	if ((info->flags & SHMEM_F_LOCKED) || sbinfo->noswap)
 		goto redirty;
 
 	if (!total_swap_pages)
@@ -1617,7 +1636,7 @@ try_split:
 		folio_mark_uptodate(folio);
 	}
 
-	if (!folio_alloc_swap(folio, __GFP_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN)) {
+	if (!folio_alloc_swap(folio)) {
 		bool first_swapped = shmem_recalc_inode(inode, 0, nr_pages);
 		int error;
 
@@ -1882,6 +1901,7 @@ static struct folio *shmem_alloc_and_add_folio(struct vm_fault *vmf,
 	struct shmem_inode_info *info = SHMEM_I(inode);
 	unsigned long suitable_orders = 0;
 	struct folio *folio = NULL;
+	pgoff_t aligned_index;
 	long pages;
 	int error, order;
 
@@ -1895,10 +1915,12 @@ static struct folio *shmem_alloc_and_add_folio(struct vm_fault *vmf,
 		order = highest_order(suitable_orders);
 		while (suitable_orders) {
 			pages = 1UL << order;
-			index = round_down(index, pages);
-			folio = shmem_alloc_folio(gfp, order, info, index);
-			if (folio)
+			aligned_index = round_down(index, pages);
+			folio = shmem_alloc_folio(gfp, order, info, aligned_index);
+			if (folio) {
+				index = aligned_index;
 				goto allocated;
+			}
 
 			if (pages == HPAGE_PMD_NR)
 				count_vm_event(THP_FILE_FALLBACK);
@@ -2254,7 +2276,8 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
 	struct address_space *mapping = inode->i_mapping;
 	struct mm_struct *fault_mm = vma ? vma->vm_mm : NULL;
 	struct shmem_inode_info *info = SHMEM_I(inode);
-	swp_entry_t swap, index_entry;
+	swp_entry_t swap;
+	softleaf_t index_entry;
 	struct swap_info_struct *si;
 	struct folio *folio = NULL;
 	bool skip_swapcache = false;
@@ -2266,7 +2289,7 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
 	swap = index_entry;
 	*foliop = NULL;
 
-	if (is_poisoned_swp_entry(index_entry))
+	if (softleaf_is_poison_marker(index_entry))
 		return -EIO;
 
 	si = get_swap_device(index_entry);
@@ -2756,8 +2779,7 @@ unsigned long shmem_get_unmapped_area(struct file *file,
 	if (len > TASK_SIZE)
 		return -ENOMEM;
 
-	addr = mm_get_unmapped_area(current->mm, file, uaddr, len, pgoff,
-				    flags);
+	addr = mm_get_unmapped_area(file, uaddr, len, pgoff, flags);
 
 	if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
 		return addr;
@@ -2835,8 +2857,7 @@ unsigned long shmem_get_unmapped_area(struct file *file,
 	if (inflated_len < len)
 		return addr;
 
-	inflated_addr = mm_get_unmapped_area(current->mm, NULL, uaddr,
-					     inflated_len, 0, flags);
+	inflated_addr = mm_get_unmapped_area(NULL, uaddr, inflated_len, 0, flags);
 	if (IS_ERR_VALUE(inflated_addr))
 		return addr;
 	if (inflated_addr & ~PAGE_MASK)
@@ -2907,15 +2928,15 @@ int shmem_lock(struct file *file, int lock, struct ucounts *ucounts)
 	 * ipc_lock_object() when called from shmctl_do_lock(),
 	 * no serialization needed when called from shm_destroy().
 	 */
-	if (lock && !(info->flags & VM_LOCKED)) {
+	if (lock && !(info->flags & SHMEM_F_LOCKED)) {
 		if (!user_shm_lock(inode->i_size, ucounts))
 			goto out_nomem;
-		info->flags |= VM_LOCKED;
+		info->flags |= SHMEM_F_LOCKED;
 		mapping_set_unevictable(file->f_mapping);
 	}
-	if (!lock && (info->flags & VM_LOCKED) && ucounts) {
+	if (!lock && (info->flags & SHMEM_F_LOCKED) && ucounts) {
 		user_shm_unlock(inode->i_size, ucounts);
-		info->flags &= ~VM_LOCKED;
+		info->flags &= ~SHMEM_F_LOCKED;
 		mapping_clear_unevictable(file->f_mapping);
 	}
 	retval = 0;
@@ -2924,16 +2945,17 @@ out_nomem:
 	return retval;
 }
 
-static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
+static int shmem_mmap_prepare(struct vm_area_desc *desc)
 {
+	struct file *file = desc->file;
 	struct inode *inode = file_inode(file);
 
 	file_accessed(file);
 	/* This is anonymous shared memory if it is unlinked at the time of mmap */
 	if (inode->i_nlink)
-		vma->vm_ops = &shmem_vm_ops;
+		desc->vm_ops = &shmem_vm_ops;
 	else
-		vma->vm_ops = &shmem_anon_vm_ops;
+		desc->vm_ops = &shmem_anon_vm_ops;
 	return 0;
 }
 
@@ -3059,7 +3081,7 @@ static struct inode *__shmem_get_inode(struct mnt_idmap *idmap,
 	spin_lock_init(&info->lock);
 	atomic_set(&info->stop_eviction, 0);
 	info->seals = F_SEAL_SEAL;
-	info->flags = flags & VM_NORESERVE;
+	info->flags = (flags & VM_NORESERVE) ? SHMEM_F_NORESERVE : 0;
 	info->i_crtime = inode_get_mtime(inode);
 	info->fsflags = (dir == NULL) ? 0 :
 		SHMEM_I(dir)->fsflags & SHMEM_FL_INHERITED;
@@ -3286,6 +3308,10 @@ shmem_write_begin(const struct kiocb *iocb, struct address_space *mapping,
 			return -EPERM;
 	}
 
+	if (unlikely((info->flags & SHMEM_F_MAPPING_FROZEN) &&
+		     pos + len > inode->i_size))
+		return -EPERM;
+
 	ret = shmem_get_folio(inode, index, pos + len, &folio, SGP_WRITE);
 	if (ret)
 		return ret;
@@ -3659,6 +3685,11 @@ static long shmem_fallocate(struct file *file, int mode, loff_t offset,
 
 	inode_lock(inode);
 
+	if (info->flags & SHMEM_F_MAPPING_FROZEN) {
+		error = -EPERM;
+		goto out;
+	}
+
 	if (mode & FALLOC_FL_PUNCH_HOLE) {
 		struct address_space *mapping = file->f_mapping;
 		loff_t unmap_start = round_up(offset, PAGE_SIZE);
@@ -3858,12 +3889,7 @@ shmem_mknod(struct mnt_idmap *idmap, struct inode *dir,
 	inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
 	inode_inc_iversion(dir);
 
-	if (IS_ENABLED(CONFIG_UNICODE) && IS_CASEFOLDED(dir))
-		d_add(dentry, inode);
-	else
-		d_instantiate(dentry, inode);
-
-	dget(dentry); /* Extra count - pin the dentry in core */
+	d_make_persistent(dentry, inode);
 	return error;
 
 out_iput:
@@ -3924,7 +3950,7 @@ static int shmem_link(struct dentry *old_dentry, struct inode *dir,
 		      struct dentry *dentry)
 {
 	struct inode *inode = d_inode(old_dentry);
-	int ret = 0;
+	int ret;
 
 	/*
 	 * No ordinary (disk based) filesystem counts links as inodes;
@@ -3936,29 +3962,19 @@ static int shmem_link(struct dentry *old_dentry, struct inode *dir,
 	if (inode->i_nlink) {
 		ret = shmem_reserve_inode(inode->i_sb, NULL);
 		if (ret)
-			goto out;
+			return ret;
 	}
 
 	ret = simple_offset_add(shmem_get_offset_ctx(dir), dentry);
 	if (ret) {
 		if (inode->i_nlink)
 			shmem_free_inode(inode->i_sb, 0);
-		goto out;
+		return ret;
 	}
 
 	dir->i_size += BOGO_DIRENT_SIZE;
-	inode_set_mtime_to_ts(dir,
-			      inode_set_ctime_to_ts(dir, inode_set_ctime_current(inode)));
 	inode_inc_iversion(dir);
-	inc_nlink(inode);
-	ihold(inode);	/* New dentry reference */
-	dget(dentry);	/* Extra pinning count for the created dentry */
-	if (IS_ENABLED(CONFIG_UNICODE) && IS_CASEFOLDED(dir))
-		d_add(dentry, inode);
-	else
-		d_instantiate(dentry, inode);
-out:
-	return ret;
+	return simple_link(old_dentry, dir, dentry);
 }
 
 static int shmem_unlink(struct inode *dir, struct dentry *dentry)
@@ -3971,11 +3987,8 @@ static int shmem_unlink(struct inode *dir, struct dentry *dentry)
 	simple_offset_remove(shmem_get_offset_ctx(dir), dentry);
 
 	dir->i_size -= BOGO_DIRENT_SIZE;
-	inode_set_mtime_to_ts(dir,
-			      inode_set_ctime_to_ts(dir, inode_set_ctime_current(inode)));
 	inode_inc_iversion(dir);
-	drop_nlink(inode);
-	dput(dentry);	/* Undo the count from "create" - does all the work */
+	simple_unlink(dir, dentry);
 
 	/*
 	 * For now, VFS can't deal with case-insensitive negative dentries, so
@@ -4130,11 +4143,7 @@ static int shmem_symlink(struct mnt_idmap *idmap, struct inode *dir,
 	dir->i_size += BOGO_DIRENT_SIZE;
 	inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
 	inode_inc_iversion(dir);
-	if (IS_ENABLED(CONFIG_UNICODE) && IS_CASEFOLDED(dir))
-		d_add(dentry, inode);
-	else
-		d_instantiate(dentry, inode);
-	dget(dentry);
+	d_make_persistent(dentry, inode);
 	return 0;
 
 out_remove_offset:
@@ -4677,7 +4686,6 @@ static int shmem_parse_one(struct fs_context *fc, struct fs_parameter *param)
 				       "Turning off swap in unprivileged tmpfs mounts unsupported");
 		}
 		ctx->noswap = true;
-		ctx->seen |= SHMEM_SEEN_NOSWAP;
 		break;
 	case Opt_quota:
 		if (fc->user_ns != &init_user_ns)
@@ -4827,14 +4835,15 @@ static int shmem_reconfigure(struct fs_context *fc)
 		err = "Current inum too high to switch to 32-bit inums";
 		goto out;
 	}
-	if ((ctx->seen & SHMEM_SEEN_NOSWAP) && ctx->noswap && !sbinfo->noswap) {
+
+	/*
+	 * "noswap" doesn't use fsparam_flag_no, i.e. there's no "swap"
+	 * counterpart for (re-)enabling swap.
+	 */
+	if (ctx->noswap && !sbinfo->noswap) {
 		err = "Cannot disable swap on remount";
 		goto out;
 	}
-	if (!(ctx->seen & SHMEM_SEEN_NOSWAP) && !ctx->noswap && sbinfo->noswap) {
-		err = "Cannot enable swap on remount if it was disabled on first mount";
-		goto out;
-	}
 
 	if (ctx->seen & SHMEM_SEEN_QUOTA &&
 	    !sb_any_quota_loaded(fc->root->d_sb)) {
@@ -5203,7 +5212,7 @@ static const struct address_space_operations shmem_aops = {
 };
 
 static const struct file_operations shmem_file_operations = {
-	.mmap		= shmem_mmap,
+	.mmap_prepare	= shmem_mmap_prepare,
 	.open		= shmem_file_open,
 	.get_unmapped_area = shmem_get_unmapped_area,
 #ifdef CONFIG_TMPFS
@@ -5334,7 +5343,7 @@ static struct file_system_type shmem_fs_type = {
 #ifdef CONFIG_TMPFS
 	.parameters	= shmem_fs_parameters,
 #endif
-	.kill_sb	= kill_litter_super,
+	.kill_sb	= kill_anon_super,
 	.fs_flags	= FS_USERNS_MOUNT | FS_ALLOW_IDMAP | FS_MGTIME,
 };
 
@@ -5772,11 +5781,11 @@ unsigned long shmem_get_unmapped_area(struct file *file,
 				      unsigned long addr, unsigned long len,
 				      unsigned long pgoff, unsigned long flags)
 {
-	return mm_get_unmapped_area(current->mm, file, addr, len, pgoff, flags);
+	return mm_get_unmapped_area(file, addr, len, pgoff, flags);
 }
 #endif
 
-void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
+void shmem_truncate_range(struct inode *inode, loff_t lstart, uoff_t lend)
 {
 	truncate_inode_pages_range(inode->i_mapping, lstart, lend);
 }
@@ -5801,8 +5810,10 @@ static inline struct inode *shmem_get_inode(struct mnt_idmap *idmap,
 /* common code */
 
 static struct file *__shmem_file_setup(struct vfsmount *mnt, const char *name,
-			loff_t size, unsigned long flags, unsigned int i_flags)
+				       loff_t size, unsigned long vm_flags,
+				       unsigned int i_flags)
 {
+	unsigned long flags = (vm_flags & VM_NORESERVE) ? SHMEM_F_NORESERVE : 0;
 	struct inode *inode;
 	struct file *res;
 
@@ -5819,7 +5830,7 @@ static struct file *__shmem_file_setup(struct vfsmount *mnt, const char *name,
 		return ERR_PTR(-ENOMEM);
 
 	inode = shmem_get_inode(&nop_mnt_idmap, mnt->mnt_sb, NULL,
-				S_IFREG | S_IRWXUGO, 0, flags);
+				S_IFREG | S_IRWXUGO, 0, vm_flags);
 	if (IS_ERR(inode)) {
 		shmem_unacct_size(flags, size);
 		return ERR_CAST(inode);
@@ -5878,14 +5889,9 @@ struct file *shmem_file_setup_with_mnt(struct vfsmount *mnt, const char *name,
 }
 EXPORT_SYMBOL_GPL(shmem_file_setup_with_mnt);
 
-/**
- * shmem_zero_setup - setup a shared anonymous mapping
- * @vma: the vma to be mmapped is prepared by do_mmap
- */
-int shmem_zero_setup(struct vm_area_struct *vma)
+static struct file *__shmem_zero_setup(unsigned long start, unsigned long end, vm_flags_t vm_flags)
 {
-	struct file *file;
-	loff_t size = vma->vm_end - vma->vm_start;
+	loff_t size = end - start;
 
 	/*
 	 * Cloning a new file under mmap_lock leads to a lock ordering conflict
@@ -5893,7 +5899,18 @@ int shmem_zero_setup(struct vm_area_struct *vma)
 	 * accessible to the user through its mapping, use S_PRIVATE flag to
 	 * bypass file security, in the same way as shmem_kernel_file_setup().
 	 */
-	file = shmem_kernel_file_setup("dev/zero", size, vma->vm_flags);
+	return shmem_kernel_file_setup("dev/zero", size, vm_flags);
+}
+
+/**
+ * shmem_zero_setup - setup a shared anonymous mapping
+ * @vma: the vma to be mmapped is prepared by do_mmap
+ * Returns: 0 on success, or error
+ */
+int shmem_zero_setup(struct vm_area_struct *vma)
+{
+	struct file *file = __shmem_zero_setup(vma->vm_start, vma->vm_end, vma->vm_flags);
+
 	if (IS_ERR(file))
 		return PTR_ERR(file);
 
@@ -5906,6 +5923,25 @@ int shmem_zero_setup(struct vm_area_struct *vma)
 }
 
 /**
+ * shmem_zero_setup_desc - same as shmem_zero_setup, but determined by VMA
+ * descriptor for convenience.
+ * @desc: Describes VMA
+ * Returns: 0 on success, or error
+ */
+int shmem_zero_setup_desc(struct vm_area_desc *desc)
+{
+	struct file *file = __shmem_zero_setup(desc->start, desc->end, desc->vm_flags);
+
+	if (IS_ERR(file))
+		return PTR_ERR(file);
+
+	desc->vm_file = file;
+	desc->vm_ops = &shmem_anon_vm_ops;
+
+	return 0;
+}
+
+/**
  * shmem_read_folio_gfp - read into page cache, using specified page allocation flags.
  * @mapping:	the folio's address_space
  * @index:	the folio index