nilfs2-fix-general-protection-fault-in-nilfs_lookup_dirty_data_buffers.patch removed from -mm tree

The quilt patch titled
Subject: nilfs2: fix general protection fault in nilfs_lookup_dirty_data_buffers()
has been removed from the -mm tree. Its filename was
nilfs2-fix-general-protection-fault-in-nilfs_lookup_dirty_data_buffers.patch

This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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From: Ryusuke Konishi <[email protected]>
Subject: nilfs2: fix general protection fault in nilfs_lookup_dirty_data_buffers()
Date: Sat, 5 Aug 2023 22:20:38 +0900

A syzbot stress test reported that create_empty_buffers() called from nilfs_lookup_dirty_data_buffers() can cause a general protection fault.

Analysis using its reproducer revealed that the back reference "mapping" from a page/folio has been changed to NULL after dirty page/folio gang lookup in nilfs_lookup_dirty_data_buffers().

Fix this issue by excluding pages/folios from being collected if, after acquiring a lock on each page/folio, its back reference "mapping" differs from the pointer to the address space struct that held the page/folio.

---

 fs/nilfs2/segment.c |    5 +++++
 1 file changed, 5 insertions(+)

@@ -725,6 +725,11 @@ static size_t nilfs_lookup_dirty_data_bu
 		struct folio *folio = fbatch.folios[i];
 
 		folio_lock(folio);
+		if (unlikely(folio->mapping != mapping)) {
+			/* Exclude folios removed from the address space */
+			folio_unlock(folio);
+			continue;
+		}
 		head = folio_buffers(folio);
 		if (!head) {
 			create_empty_buffers(&folio->page, i_blocksize(inode), 0);

_

Patches currently in -mm which might be from [email protected] are

nilfs2-fix-warning-in-mark_buffer_dirty-due-to-discarded-buffer-reuse.patch