Re: [syzbot] [efi?] [fs?] possible deadlock in efivarfs_actor

[Hillf Danton]

On Sat, 08 Mar 2025 18:52:38 -0800
> syzbot found the following issue on:
> 
> HEAD commit:    e056da87c780 Merge remote-tracking branch 'will/for-next/p..
> git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13b97c64580000

#syz test upstream  master

--- x/fs/efivarfs/super.c
+++ y/fs/efivarfs/super.c
@@ -421,7 +421,7 @@ static bool efivarfs_actor(struct dir_co
 	if (err)
 		size = 0;
 
-	inode_lock(inode);
+	inode_lock_nested(inode, I_MUTEX_CHILD);
 	i_size_write(inode, size);
 	inode_unlock(inode);
 
--