====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.5.673/7842 is trying to acquire lock: ffff0000d814a410 (sb_writers#3){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:493 but task is already holding lock: ffff0000dc947230 (&ovl_i_lock_key[depth]){+.+.}-{4:4}, at: ovl_inode_lock_interruptible fs/overlayfs/overlayfs.h:705 [inline] ffff0000dc947230 (&ovl_i_lock_key[depth]){+.+.}-{4:4}, at: ovl_nlink_start+0xc8/0x350 fs/overlayfs/util.c:1173 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&ovl_i_lock_key[depth]){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x160/0xef8 kernel/locking/mutex.c:820 mutex_lock_interruptible_nested+0x24/0x30 kernel/locking/mutex.c:898 ovl_inode_lock_interruptible fs/overlayfs/overlayfs.h:705 [inline] ovl_copy_up_start+0x58/0x264 fs/overlayfs/util.c:735 ovl_copy_up_one fs/overlayfs/copy_up.c:1182 [inline] ovl_copy_up_flags+0x768/0x28a4 fs/overlayfs/copy_up.c:1243 ovl_copy_up+0x24/0x34 fs/overlayfs/copy_up.c:1282 ovl_link+0x8c/0x26c fs/overlayfs/dir.c:774 vfs_link+0x40c/0x580 fs/namei.c:5774 filename_linkat+0x224/0x478 fs/namei.c:5842 __do_sys_linkat fs/namei.c:5868 [inline] __se_sys_linkat fs/namei.c:5863 [inline] __arm64_sys_linkat+0xe8/0x118 fs/namei.c:5863 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:140 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594 -> #1 (&ovl_i_mutex_key[depth]){+.+.}-{4:4}: down_write+0x50/0xc0 kernel/locking/rwsem.c:1625 inode_lock include/linux/fs.h:1029 [inline] lock_two_nondirectories+0xc4/0x148 fs/inode.c:1254 ext4_move_extents+0x194/0x3580 fs/ext4/move_extent.c:589 __ext4_ioctl fs/ext4/ioctl.c:1657 [inline] ext4_ioctl+0x2a14/0x4234 fs/ext4/ioctl.c:1922 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __arm64_sys_ioctl+0x14c/0x1c4 fs/ioctl.c:583 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:140 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594 -> #0 (sb_writers#3){.+.+}-{0:0}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x1780/0x2f44 kernel/locking/lockdep.c:5237 lock_acquire+0x140/0x368 kernel/locking/lockdep.c:5868 percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline] percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline] __sb_start_write include/linux/fs/super.h:19 [inline] sb_start_write+0x5c/0x294 include/linux/fs/super.h:125 mnt_want_write+0x44/0x9c fs/namespace.c:493 ovl_want_write fs/overlayfs/util.c:38 [inline] ovl_nlink_start+0x154/0x350 fs/overlayfs/util.c:1177 ovl_do_remove+0x1c0/0xa04 fs/overlayfs/dir.c:954 ovl_rmdir+0x24/0x34 fs/overlayfs/dir.c:993 vfs_rmdir+0x34c/0x5a0 fs/namei.c:5366 filename_rmdir+0x208/0x3dc fs/namei.c:5421 __do_sys_unlinkat fs/namei.c:5596 [inline] __se_sys_unlinkat fs/namei.c:5589 [inline] __arm64_sys_unlinkat+0xc8/0x104 fs/namei.c:5589 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:140 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594 other info that might help us debug this: Chain exists of: sb_writers#3 --> &ovl_i_mutex_key[depth] --> &ovl_i_lock_key[depth] Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&ovl_i_lock_key[depth]); lock(&ovl_i_mutex_key[depth]); lock(&ovl_i_lock_key[depth]); rlock(sb_writers#3); *** DEADLOCK *** 4 locks held by syz.5.673/7842: #0: ffff0000d924c410 (sb_writers#17){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:493 #1: ffff0000dc944300 (&ovl_i_mutex_dir_key[depth]/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1074 [inline] #1: ffff0000dc944300 (&ovl_i_mutex_dir_key[depth]/1){+.+.}-{4:4}, at: __start_dirop+0xa0/0xf4 fs/namei.c:2914 #2: ffff0000dc946ec0 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}, at: inode_lock include/linux/fs.h:1029 [inline] #2: ffff0000dc946ec0 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}, at: vfs_rmdir+0x110/0x5a0 fs/namei.c:5351 #3: ffff0000dc947230 (&ovl_i_lock_key[depth]){+.+.}-{4:4}, at: ovl_inode_lock_interruptible fs/overlayfs/overlayfs.h:705 [inline] #3: ffff0000dc947230 (&ovl_i_lock_key[depth]){+.+.}-{4:4}, at: ovl_nlink_start+0xc8/0x350 fs/overlayfs/util.c:1173 stack backtrace: CPU: 1 UID: 0 PID: 7842 Comm: syz.5.673 Tainted: G L syzkaller #0 PREEMPT Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 Call trace: show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (C) __dump_stack+0x30/0x40 lib/dump_stack.c:94 dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120 dump_stack+0x1c/0x28 lib/dump_stack.c:129 print_circular_bug+0x328/0x330 kernel/locking/lockdep.c:2043 check_noncircular+0x158/0x174 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x1780/0x2f44 kernel/locking/lockdep.c:5237 lock_acquire+0x140/0x368 kernel/locking/lockdep.c:5868 percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline] percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline] __sb_start_write include/linux/fs/super.h:19 [inline] sb_start_write+0x5c/0x294 include/linux/fs/super.h:125 mnt_want_write+0x44/0x9c fs/namespace.c:493 ovl_want_write fs/overlayfs/util.c:38 [inline] ovl_nlink_start+0x154/0x350 fs/overlayfs/util.c:1177 ovl_do_remove+0x1c0/0xa04 fs/overlayfs/dir.c:954 ovl_rmdir+0x24/0x34 fs/overlayfs/dir.c:993 vfs_rmdir+0x34c/0x5a0 fs/namei.c:5366 filename_rmdir+0x208/0x3dc fs/namei.c:5421 __do_sys_unlinkat fs/namei.c:5596 [inline] __se_sys_unlinkat fs/namei.c:5589 [inline] __arm64_sys_unlinkat+0xc8/0x104 fs/namei.c:5589 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:140 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594