linux-kernel - Re: [syzbot] [ext4?] WARNING: locking bug in ext4_xattr_inode_update

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Message-Id: <20240411113939.749-1-hdanton@sina.com>
Date: Thu, 11 Apr 2024 19:39:39 +0800
From: Hillf Danton <hdanton@...a.com>
To: syzbot <syzbot+3ca210b2c10e57015b3c@...kaller.appspotmail.com>
Cc: linux-kernel@...r.kernel.org,
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [ext4?] WARNING: locking bug in ext4_xattr_inode_update_ref (3)

On Thu, 11 Apr 2024 02:48:27 -0700
> syzbot found the following issue on:
> 
> HEAD commit:    f2f80ac80987 Merge tag 'nfsd-6.9-2' of git://git.kernel.or..
> git tree:       upstream
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1614c105180000

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git  f2f80ac80987

--- x/fs/ext4/xattr.c
+++ y/fs/ext4/xattr.c
@@ -119,11 +119,12 @@ ext4_expand_inode_array(struct ext4_xatt
 			struct inode *inode);
 
 #ifdef CONFIG_LOCKDEP
+static struct lock_class_key ea_i_rwsem_key;
 void ext4_xattr_inode_set_class(struct inode *ea_inode)
 {
 	struct ext4_inode_info *ei = EXT4_I(ea_inode);
 
-	lockdep_set_subclass(&ea_inode->i_rwsem, 1);
+	lockdep_set_class(&ea_inode->i_rwsem, &ea_i_rwsem_key);
 	(void) ei;	/* shut up clang warning if !CONFIG_LOCKDEP */
 	lockdep_set_subclass(&ei->i_data_sem, I_DATA_SEM_EA);
 }
--