From: Liam R. Howlett <Liam.Howlett@oracle.com>
Date: Fri, 24 Oct 2025 15:46:03 +0000 (-0400)
Subject: mm/shmem: Reduce duplicate userfaultfd code
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=779352201217c063f7d6a83cd29ede3c00fd6913;p=users%2Fjedix%2Flinux-maple.git

mm/shmem: Reduce duplicate userfaultfd code

shmem has duplicate code blocks in functions that were earlier split
out.  The duplicate code can be removed by using a function without much
difficulty.

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

diff --git a/mm/shmem.c b/mm/shmem.c
index 1bc84fb55aa8..fe079e2c8f30 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -3159,33 +3159,12 @@ static ssize_t shmem_is_dst_valid(struct vm_area_struct *dst_vma,
 	return 0;
 }
 
-
-static int shmem_mfill_atomic_pte_zeropage(struct vm_area_struct *dst_vma,
-		unsigned long dst_addr)
+static inline int shmem_mfill_complete(struct vm_area_struct *dst_vma,
+		unsigned long dst_addr, pmd_t *dst_pmd, pgoff_t pgoff,
+		struct folio *folio, struct inode *inode, gfp_t gfp)
 {
-	struct inode *inode = file_inode(dst_vma->vm_file);
-	struct shmem_inode_info *info = SHMEM_I(inode);
-	struct address_space *mapping = inode->i_mapping;
-	gfp_t gfp = mapping_gfp_mask(mapping);
-	pgoff_t pgoff = linear_page_index(dst_vma, dst_addr);
-	struct folio *folio;
-	int ret;
 	pgoff_t max_off;
-	pmd_t *dst_pmd;
-
-	ret = uffd_get_dst_pmd(dst_vma, dst_addr, &dst_pmd);
-	if (ret)
-		return ret;
-
-	if (shmem_inode_acct_blocks(inode, 1))
-		return -ENOMEM;
-
-	ret = -ENOMEM;
-	folio = shmem_alloc_folio(gfp, 0, info, pgoff);
-	if (!folio)
-		goto out_unacct_blocks;
-
-	clear_user_highpage(&folio->page, dst_addr);
+	int ret;
 
 	VM_BUG_ON(folio_test_locked(folio));
 	VM_BUG_ON(folio_test_swapbacked(folio));
@@ -3201,7 +3180,8 @@ static int shmem_mfill_atomic_pte_zeropage(struct vm_area_struct *dst_vma,
 	ret = mem_cgroup_charge(folio, dst_vma->vm_mm, gfp);
 	if (ret)
 		goto out_release;
-	ret = shmem_add_to_page_cache(folio, mapping, pgoff, NULL, gfp);
+	ret = shmem_add_to_page_cache(folio, inode->i_mapping, pgoff, NULL,
+				      gfp);
 	if (ret)
 		goto out_release;
 
@@ -3218,11 +3198,42 @@ out_delete_from_cache:
 out_release:
 	folio_unlock(folio);
 	folio_put(folio);
-out_unacct_blocks:
 	shmem_inode_unacct_blocks(inode, 1);
 	return ret;
 }
 
+static int shmem_mfill_atomic_pte_zeropage(struct vm_area_struct *dst_vma,
+		unsigned long dst_addr)
+{
+	struct inode *inode = file_inode(dst_vma->vm_file);
+	struct shmem_inode_info *info = SHMEM_I(inode);
+	gfp_t gfp = mapping_gfp_mask(inode->i_mapping);
+	pgoff_t pgoff = linear_page_index(dst_vma, dst_addr);
+	struct folio *folio;
+	int ret;
+	pmd_t *dst_pmd;
+
+	ret = uffd_get_dst_pmd(dst_vma, dst_addr, &dst_pmd);
+	if (ret)
+		return ret;
+
+	if (shmem_inode_acct_blocks(inode, 1))
+		return -ENOMEM;
+
+	ret = -ENOMEM;
+	folio = shmem_alloc_folio(gfp, 0, info, pgoff);
+	if (!folio) {
+		shmem_inode_unacct_blocks(inode, 1);
+		return -ENOMEM;
+	}
+
+	clear_user_highpage(&folio->page, dst_addr);
+
+	ret = shmem_mfill_complete(dst_vma, dst_addr, dst_pmd, pgoff, folio,
+				   inode, gfp);
+	return ret;
+}
+
 static int shmem_mfill_atomic_pte_copy(struct vm_area_struct *dst_vma,
 		unsigned long dst_addr, unsigned long src_addr,
 		uffd_flags_t flags, struct folio **foliop,
@@ -3236,7 +3247,6 @@ static int shmem_mfill_atomic_pte_copy(struct vm_area_struct *dst_vma,
 	void *page_kaddr;
 	struct folio *folio;
 	int ret;
-	pgoff_t max_off;
 	pmd_t *dst_pmd;
 
 	ret = uffd_get_dst_pmd(dst_vma, dst_addr, &dst_pmd);
@@ -3299,37 +3309,10 @@ static int shmem_mfill_atomic_pte_copy(struct vm_area_struct *dst_vma,
 		*foliop = NULL;
 	}
 
-	VM_BUG_ON(folio_test_locked(folio));
-	VM_BUG_ON(folio_test_swapbacked(folio));
-	__folio_set_locked(folio);
-	__folio_set_swapbacked(folio);
-	__folio_mark_uptodate(folio);
-
-	ret = -EFAULT;
-	max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
-	if (unlikely(pgoff >= max_off))
-		goto out_release;
-
-	ret = mem_cgroup_charge(folio, dst_vma->vm_mm, gfp);
-	if (ret)
-		goto out_release;
-	ret = shmem_add_to_page_cache(folio, mapping, pgoff, NULL, gfp);
-	if (ret)
-		goto out_release;
-
-	ret = mfill_atomic_install_pte(dst_pmd, dst_vma, dst_addr,
-				       &folio->page, true, flags);
-	if (ret)
-		goto out_delete_from_cache;
+	ret = shmem_mfill_complete(dst_vma, dst_addr, dst_pmd, pgoff, folio,
+				   inode, gfp);
+	return ret;
 
-	shmem_recalc_inode(inode, 1, 0);
-	folio_unlock(folio);
-	return 0;
-out_delete_from_cache:
-	filemap_remove_folio(folio);
-out_release:
-	folio_unlock(folio);
-	folio_put(folio);
 out_unacct_blocks:
 	shmem_inode_unacct_blocks(inode, 1);
 	return ret;