overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
======================================================
WARNING: possible circular locking dependency detected
4.19.107-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.2/17698 is trying to acquire lock:
00000000484cda04 (sb_writers#4){.+.+}, at: sb_start_write include/linux/fs.h:1578 [inline]
00000000484cda04 (sb_writers#4){.+.+}, at: mnt_want_write+0x3a/0xb0 fs/namespace.c:360

but task is already holding lock:
00000000b5228392 (&ovl_i_mutex_dir_key[depth]){++++}, at: inode_lock include/linux/fs.h:747 [inline]
00000000b5228392 (&ovl_i_mutex_dir_key[depth]){++++}, at: vfs_setxattr+0x92/0xf0 fs/xattr.c:218

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&ovl_i_mutex_dir_key[depth]){++++}:
       inode_lock_shared include/linux/fs.h:757 [inline]
       do_last fs/namei.c:3326 [inline]
       path_openat+0x1d18/0x4200 fs/namei.c:3537
       do_filp_open+0x1a1/0x280 fs/namei.c:3567
       do_open_execat+0x124/0x5b0 fs/exec.c:853
       __do_execve_file.isra.0+0x1577/0x2110 fs/exec.c:1755
       do_execveat_common fs/exec.c:1866 [inline]
       do_execve fs/exec.c:1883 [inline]
       __do_sys_execve fs/exec.c:1964 [inline]
       __se_sys_execve fs/exec.c:1959 [inline]
       __x64_sys_execve+0x8a/0xb0 fs/exec.c:1959
       do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #2 (&sig->cred_guard_mutex){+.+.}:
       do_io_accounting+0x1da/0x7b0 fs/proc/base.c:2738
       proc_single_show+0xeb/0x170 fs/proc/base.c:755
       seq_read+0x4b9/0x10f0 fs/seq_file.c:229
       do_loop_readv_writev fs/read_write.c:701 [inline]
       do_loop_readv_writev fs/read_write.c:688 [inline]
       do_iter_read+0x46b/0x640 fs/read_write.c:925
       vfs_readv+0xf0/0x160 fs/read_write.c:987
       do_preadv+0x1b6/0x270 fs/read_write.c:1071
       do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #1 (&p->lock){+.+.}:
       seq_read+0x6b/0x10f0 fs/seq_file.c:161
       do_loop_readv_writev fs/read_write.c:701 [inline]
       do_loop_readv_writev fs/read_write.c:688 [inline]
       do_iter_read+0x46b/0x640 fs/read_write.c:925
       vfs_readv+0xf0/0x160 fs/read_write.c:987
       kernel_readv fs/splice.c:362 [inline]
       default_file_splice_read+0x478/0x970 fs/splice.c:417
       do_splice_to+0x10e/0x160 fs/splice.c:881
       splice_direct_to_actor+0x2b9/0x8d0 fs/splice.c:959
       do_splice_direct+0x1a8/0x270 fs/splice.c:1068
       do_sendfile+0x549/0xc10 fs/read_write.c:1447
       __do_sys_sendfile64 fs/read_write.c:1508 [inline]
       __se_sys_sendfile64 fs/read_write.c:1494 [inline]
       __x64_sys_sendfile64+0x1cc/0x210 fs/read_write.c:1494
       do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #0 (sb_writers#4){.+.+}:
       percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:36 [inline]
       percpu_down_read include/linux/percpu-rwsem.h:59 [inline]
       __sb_start_write+0x1e6/0x340 fs/super.c:1387
       sb_start_write include/linux/fs.h:1578 [inline]
       mnt_want_write+0x3a/0xb0 fs/namespace.c:360
       ovl_xattr_set+0x53/0x5a0 fs/overlayfs/inode.c:338
       __vfs_setxattr+0x10e/0x170 fs/xattr.c:149
       __vfs_setxattr_noperm+0x11a/0x410 fs/xattr.c:180
       vfs_setxattr+0xd2/0xf0 fs/xattr.c:223
       setxattr+0x23d/0x330 fs/xattr.c:450
       path_setxattr+0x170/0x190 fs/xattr.c:469
       __do_sys_lsetxattr fs/xattr.c:491 [inline]
       __se_sys_lsetxattr fs/xattr.c:487 [inline]
       __x64_sys_lsetxattr+0xbd/0x150 fs/xattr.c:487
       do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

other info that might help us debug this:

Chain exists of:
  sb_writers#4 --> &sig->cred_guard_mutex --> &ovl_i_mutex_dir_key[depth]

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&ovl_i_mutex_dir_key[depth]);
                               lock(&sig->cred_guard_mutex);
                               lock(&ovl_i_mutex_dir_key[depth]);
  lock(sb_writers#4);

 *** DEADLOCK ***

2 locks held by syz-executor.2/17698:
 #0: 0000000094da3619 (sb_writers#13){.+.+}, at: sb_start_write include/linux/fs.h:1578 [inline]
 #0: 0000000094da3619 (sb_writers#13){.+.+}, at: mnt_want_write+0x3a/0xb0 fs/namespace.c:360
 #1: 00000000b5228392 (&ovl_i_mutex_dir_key[depth]){++++}, at: inode_lock include/linux/fs.h:747 [inline]
 #1: 00000000b5228392 (&ovl_i_mutex_dir_key[depth]){++++}, at: vfs_setxattr+0x92/0xf0 fs/xattr.c:218

stack backtrace:
CPU: 1 PID: 17698 Comm: syz-executor.2 Not tainted 4.19.107-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x188/0x20d lib/dump_stack.c:118
 print_circular_bug.isra.0.cold+0x1c4/0x282 kernel/locking/lockdep.c:1221
 check_prev_add kernel/locking/lockdep.c:1861 [inline]
 check_prevs_add kernel/locking/lockdep.c:1974 [inline]
 validate_chain kernel/locking/lockdep.c:2415 [inline]
 __lock_acquire+0x2e19/0x49c0 kernel/locking/lockdep.c:3411
 lock_acquire+0x170/0x400 kernel/locking/lockdep.c:3903
 percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:36 [inline]
 percpu_down_read include/linux/percpu-rwsem.h:59 [inline]
 __sb_start_write+0x1e6/0x340 fs/super.c:1387
 sb_start_write include/linux/fs.h:1578 [inline]
 mnt_want_write+0x3a/0xb0 fs/namespace.c:360
 ovl_xattr_set+0x53/0x5a0 fs/overlayfs/inode.c:338
 __vfs_setxattr+0x10e/0x170 fs/xattr.c:149
 __vfs_setxattr_noperm+0x11a/0x410 fs/xattr.c:180
 vfs_setxattr+0xd2/0xf0 fs/xattr.c:223
 setxattr+0x23d/0x330 fs/xattr.c:450
 path_setxattr+0x170/0x190 fs/xattr.c:469
 __do_sys_lsetxattr fs/xattr.c:491 [inline]
 __se_sys_lsetxattr fs/xattr.c:487 [inline]
 __x64_sys_lsetxattr+0xbd/0x150 fs/xattr.c:487
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c479
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f409090cc78 EFLAGS: 00000246 ORIG_RAX: 00000000000000bd
RAX: ffffffffffffffda RBX: 00007f409090d6d4 RCX: 000000000045c479
RDX: 0000000000000000 RSI: 0000000020000200 RDI: 0000000020000140
RBP: 000000000076bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 000000000000071a R14: 00000000004c9a45 R15: 000000000076bf2c
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: failed to resolve 'file0': -2
overlayfs: failed to resolve 'file0': -2
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: failed to resolve 'file0': -2
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: failed to resolve 'file0': -2
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: failed to resolve 'file0': -2
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: failed to resolve 'file0': -2
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: failed to resolve 'file0': -2
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: failed to resolve 'file0': -2
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: failed to resolve 'file0': -2
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: failed to resolve 'file0': -2
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: failed to resolve 'file0': -2
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: failed to resolve 'file0': -2
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: failed to resolve 'file0': -2
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: failed to resolve 'file0': -2
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: failed to resolve 'file0': -2
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: failed to resolve 'file0': -2
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: failed to resolve 'file0': -2
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: failed to resolve 'file0': -2
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: failed to resolve 'file0': -2
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: './bus' not a directory
overlayfs: filesystem on './file0' not supported as upperdir
overlayfs: filesystem on './file0' not supported as upperdir