#syz test

---
 fs/hugetlbfs/inode.c    | 33 ++++++++++++++++++++++-----------
 include/linux/hugetlb.h |  2 +-
 include/linux/pagemap.h |  6 ++++++
 3 files changed, 29 insertions(+), 12 deletions(-)

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 9c94ed8c3ab0..a8f33b72a8a6 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -643,17 +643,16 @@ static void hugetlb_vmtruncate(struct inode *inode, loff_t offset)
 	remove_inode_hugepages(inode, offset, LLONG_MAX);
 }
 
-static void hugetlbfs_zero_partial_page(struct hstate *h,
-					struct address_space *mapping,
-					loff_t start,
-					loff_t end)
+static int hugetlbfs_zero_partial_page(struct hstate *h,
+				       struct address_space *mapping,
+				       loff_t start, loff_t end)
 {
 	pgoff_t idx = start >> huge_page_shift(h);
 	struct folio *folio;
 
 	folio = filemap_lock_hugetlb_folio(h, mapping, idx);
 	if (IS_ERR(folio))
-		return;
+		return PTR_ERR(folio);
 
 	start = start & ~huge_page_mask(h);
 	end = end & ~huge_page_mask(h);
@@ -673,6 +672,7 @@ static long hugetlbfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
 	struct hstate *h = hstate_inode(inode);
 	loff_t hpage_size = huge_page_size(h);
 	loff_t hole_start, hole_end;
+	int rc;
 
 	/*
 	 * hole_start and hole_end indicate the full pages within the hole.
@@ -688,12 +688,18 @@ static long hugetlbfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
 		return -EPERM;
 	}
 
+repeat:
 	i_mmap_lock_write(mapping);
 
 	/* If range starts before first full page, zero partial page. */
-	if (offset < hole_start)
-		hugetlbfs_zero_partial_page(h, mapping,
-				offset, min(offset + len, hole_start));
+	if (offset < hole_start) {
+		rc = hugetlbfs_zero_partial_page(h, mapping, offset,
+						 min(offset + len, hole_start));
+		if (rc == -EAGAIN) {
+			i_mmap_unlock_write(mapping);
+			goto repeat;
+		}
+	}
 
 	/* Unmap users of full pages in the hole. */
 	if (hole_end > hole_start) {
@@ -704,9 +710,14 @@ static long hugetlbfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
 	}
 
 	/* If range extends beyond last full page, zero partial page. */
-	if ((offset + len) > hole_end && (offset + len) > hole_start)
-		hugetlbfs_zero_partial_page(h, mapping,
-				hole_end, offset + len);
+	if ((offset + len) > hole_end && (offset + len) > hole_start) {
+		rc = hugetlbfs_zero_partial_page(h, mapping, hole_end,
+						 offset + len);
+		if (rc == -EAGAIN) {
+			i_mmap_unlock_write(mapping);
+			goto repeat;
+		}
+	}
 
 	i_mmap_unlock_write(mapping);
 
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 8e63e46b8e1f..e7d99183361a 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -811,7 +811,7 @@ static inline unsigned int blocks_per_huge_page(struct hstate *h)
 static inline struct folio *filemap_lock_hugetlb_folio(struct hstate *h,
 				struct address_space *mapping, pgoff_t idx)
 {
-	return filemap_lock_folio(mapping, idx << huge_page_order(h));
+	return filemap_lock_folio_nowait(mapping, idx << huge_page_order(h));
 }
 
 #include <asm/hugetlb.h>
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 09b581c1d878..94f31035fe1d 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -820,6 +820,12 @@ static inline struct folio *filemap_lock_folio(struct address_space *mapping,
 	return __filemap_get_folio(mapping, index, FGP_LOCK, 0);
 }
 
+static inline struct folio *filemap_lock_folio_nowait(struct address_space *mapping,
+						      pgoff_t index)
+{
+	return __filemap_get_folio(mapping, index, FGP_LOCK | FGP_NOWAIT, 0);
+}
+
 /**
  * filemap_grab_folio - grab a folio from the page cache
  * @mapping: The address space to search
-- 
2.43.0

Hello,

syzbot tried to test the proposed patch but the build/boot failed:

fs/hugetlbfs/inode.c:676:1: error: non-void function does not return a value in all control paths [-Werror,-Wreturn-type]


Tested on:

commit:         f0b9d8eb Merge tag 'nfsd-6.19-3' of git://git.kernel.o..
git tree:       upstream
kernel config:  https://syzkaller.appspot.com/x/.config?x=67b63a24f3c26fca
dashboard link: https://syzkaller.appspot.com/bug?extid=2d9c96466c978346b55f
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=163a1074580000