====================================================== WARNING: possible circular locking dependency detected 4.14.216-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.0/25908 is trying to acquire lock: (&ovl_i_mutex_dir_key[depth]){++++}, at: [] iterate_dir+0x387/0x5e0 fs/readdir.c:43 but task is already holding lock: (sb_writers#3){.+.+}, at: [] sb_start_write include/linux/fs.h:1549 [inline] (sb_writers#3){.+.+}, at: [] mnt_want_write+0x3a/0xb0 fs/namespace.c:386 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (sb_writers#3){.+.+}: 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+0x64/0x260 fs/super.c:1342 sb_start_write include/linux/fs.h:1549 [inline] mnt_want_write+0x3a/0xb0 fs/namespace.c:386 ovl_create_object+0x75/0x1d0 fs/overlayfs/dir.c:538 lookup_open+0x77a/0x1750 fs/namei.c:3241 do_last fs/namei.c:3334 [inline] path_openat+0xe08/0x2970 fs/namei.c:3569 do_filp_open+0x179/0x3c0 fs/namei.c:3603 do_sys_open+0x296/0x410 fs/open.c:1081 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb -> #0 (&ovl_i_mutex_dir_key[depth]){++++}: lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998 down_write_killable+0x37/0xb0 kernel/locking/rwsem.c:68 iterate_dir+0x387/0x5e0 fs/readdir.c:43 ovl_dir_read fs/overlayfs/readdir.c:306 [inline] ovl_dir_read_merged+0x2c5/0x430 fs/overlayfs/readdir.c:365 ovl_check_empty_dir+0x6e/0x200 fs/overlayfs/readdir.c:870 ovl_check_empty_and_clear+0x72/0xe0 fs/overlayfs/dir.c:306 ovl_remove_and_whiteout fs/overlayfs/dir.c:647 [inline] ovl_do_remove+0x565/0xb90 fs/overlayfs/dir.c:775 vfs_rmdir.part.0+0x144/0x390 fs/namei.c:3908 vfs_rmdir fs/namei.c:3893 [inline] do_rmdir+0x334/0x3c0 fs/namei.c:3968 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(sb_writers#3); lock(&ovl_i_mutex_dir_key[depth]); lock(sb_writers#3); lock(&ovl_i_mutex_dir_key[depth]); *** DEADLOCK *** 4 locks held by syz-executor.0/25908: #0: (sb_writers#17){.+.+}, at: [] sb_start_write include/linux/fs.h:1549 [inline] #0: (sb_writers#17){.+.+}, at: [] mnt_want_write+0x3a/0xb0 fs/namespace.c:386 #1: (&ovl_i_mutex_dir_key[depth]#2/1){+.+.}, at: [] inode_lock_nested include/linux/fs.h:754 [inline] #1: (&ovl_i_mutex_dir_key[depth]#2/1){+.+.}, at: [] do_rmdir+0x1de/0x3c0 fs/namei.c:3956 #2: (&ovl_i_mutex_dir_key[depth]#2){++++}, at: [] inode_lock include/linux/fs.h:719 [inline] #2: (&ovl_i_mutex_dir_key[depth]#2){++++}, at: [] vfs_rmdir.part.0+0x5c/0x390 fs/namei.c:3897 #3: (sb_writers#3){.+.+}, at: [] sb_start_write include/linux/fs.h:1549 [inline] #3: (sb_writers#3){.+.+}, at: [] mnt_want_write+0x3a/0xb0 fs/namespace.c:386 stack backtrace: CPU: 0 PID: 25908 Comm: syz-executor.0 Not tainted 4.14.216-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x1b2/0x281 lib/dump_stack.c:58 print_circular_bug.constprop.0.cold+0x2d7/0x41e kernel/locking/lockdep.c:1258 check_prev_add kernel/locking/lockdep.c:1905 [inline] check_prevs_add kernel/locking/lockdep.c:2022 [inline] validate_chain kernel/locking/lockdep.c:2464 [inline] __lock_acquire+0x2e0e/0x3f20 kernel/locking/lockdep.c:3491 lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998 down_write_killable+0x37/0xb0 kernel/locking/rwsem.c:68 iterate_dir+0x387/0x5e0 fs/readdir.c:43 ovl_dir_read fs/overlayfs/readdir.c:306 [inline] ovl_dir_read_merged+0x2c5/0x430 fs/overlayfs/readdir.c:365 ovl_check_empty_dir+0x6e/0x200 fs/overlayfs/readdir.c:870 ovl_check_empty_and_clear+0x72/0xe0 fs/overlayfs/dir.c:306 ovl_remove_and_whiteout fs/overlayfs/dir.c:647 [inline] ovl_do_remove+0x565/0xb90 fs/overlayfs/dir.c:775 vfs_rmdir.part.0+0x144/0x390 fs/namei.c:3908 vfs_rmdir fs/namei.c:3893 [inline] do_rmdir+0x334/0x3c0 fs/namei.c:3968 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x45e219 RSP: 002b:00007f5dbd6a3c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000054 RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 000000000045e219 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000180 RBP: 000000000119bfb0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000119bf8c R13: 00007fffc28b9fbf R14: 00007f5dbd6a49c0 R15: 000000000119bf8c squashfs: SQUASHFS error: Please update your kernel overlayfs: fs on '.' does not support file handles, falling back to index=off. overlayfs: maximum fs stacking depth exceeded overlayfs: filesystem on './bus' not supported as upperdir squashfs: SQUASHFS error: Major/Minor mismatch, trying to mount newer 25604.0 filesystem squashfs: SQUASHFS error: Please update your kernel overlayfs: fs on './file0' does not support file handles, falling back to index=off. overlayfs: fs on './file0' does not support file handles, falling back to index=off. overlayfs: fs on './file0' does not support file handles, falling back to index=off. squashfs: SQUASHFS error: Major/Minor mismatch, trying to mount newer 25604.0 filesystem squashfs: SQUASHFS error: Please update your kernel overlayfs: fs on './file0' does not support file handles, falling back to index=off. overlayfs: fs on './file0' does not support file handles, falling back to index=off. overlayfs: fs on './file0' does not support file handles, falling back to index=off. overlayfs: fs on './file0' does not support file handles, falling back to index=off. squashfs: SQUASHFS error: Major/Minor mismatch, trying to mount newer 25604.0 filesystem overlayfs: fs on './file0' does not support file handles, falling back to index=off. squashfs: SQUASHFS error: Please update your kernel overlayfs: fs on './file0' does not support file handles, falling back to index=off. overlayfs: fs on './file0' does not support file handles, falling back to index=off. overlayfs: fs on './file0' does not support file handles, falling back to index=off. overlayfs: fs on './file0' does not support file handles, falling back to index=off. squashfs: SQUASHFS error: Major/Minor mismatch, trying to mount newer 25604.0 filesystem squashfs: SQUASHFS error: Please update your kernel kvm_hv_set_msr: 4 callbacks suppressed kvm [26033]: vcpu0, guest rIP: 0x13c Hyper-V uhandled wrmsr: 0x40000024 data 0xf kvm [26033]: vcpu0, guest rIP: 0x14c Hyper-V uhandled wrmsr: 0x40000077 data 0x71 kvm [26033]: vcpu0, guest rIP: 0x14c Hyper-V uhandled wrmsr: 0x40000028 data 0xef kvm [26033]: vcpu0, guest rIP: 0x13c Hyper-V uhandled wrmsr: 0x40000057 data 0x51 kvm [26033]: vcpu0, guest rIP: 0x14c Hyper-V uhandled wrmsr: 0x4000002a data 0x41 kvm [26033]: vcpu0, guest rIP: 0x14c Hyper-V uhandled wrmsr: 0x4000006a data 0x41 kvm [26033]: vcpu0, guest rIP: 0x14c Hyper-V uhandled wrmsr: 0x40000022 data 0xd5 kvm [26033]: vcpu0, guest rIP: 0x14c Hyper-V uhandled wrmsr: 0x40000085 data 0x45 kvm [26033]: vcpu0, guest rIP: 0x14c Hyper-V uhandled wrmsr: 0x40000015 data 0xb9 kvm [26033]: vcpu0, guest rIP: 0x14c Hyper-V uhandled wrmsr: 0x40000041 data 0x2b overlayfs: workdir and upperdir must reside under the same mount print_req_error: I/O error, dev loop7, sector 0 print_req_error: I/O error, dev loop7, sector 0 Buffer I/O error on dev loop7, logical block 0, async page read