====================================================== WARNING: possible circular locking dependency detected 5.1.0-rc6+ #83 Not tainted ------------------------------------------------------ syz-executor.3/12811 is trying to acquire lock: 00000000d1fb5fad (&ovl_i_mutex_key[depth]){+.+.}, at: inode_lock include/linux/fs.h:772 [inline] 00000000d1fb5fad (&ovl_i_mutex_key[depth]){+.+.}, at: ovl_write_iter+0x148/0xc20 fs/overlayfs/file.c:231 but task is already holding lock: 00000000d6a9923f (&acct->lock#2){+.+.}, at: acct_get kernel/acct.c:161 [inline] 00000000d6a9923f (&acct->lock#2){+.+.}, at: slow_acct_process kernel/acct.c:577 [inline] 00000000d6a9923f (&acct->lock#2){+.+.}, at: acct_process+0x2e5/0x61e kernel/acct.c:605 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&acct->lock#2){+.+.}: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4211 __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 acct_pin_kill+0x27/0x100 kernel/acct.c:173 pin_kill+0x18f/0x860 fs/fs_pin.c:50 acct_on+0x574/0x790 kernel/acct.c:254 __do_sys_acct kernel/acct.c:286 [inline] __se_sys_acct kernel/acct.c:273 [inline] __x64_sys_acct+0xae/0x200 kernel/acct.c:273 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #1 (sb_writers#4){.+.+}: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4211 percpu_down_read include/linux/percpu-rwsem.h:36 [inline] __sb_start_write+0x20b/0x360 fs/super.c:1613 sb_start_write include/linux/fs.h:1621 [inline] mnt_want_write+0x3f/0xc0 fs/namespace.c:358 ovl_want_write+0x76/0xa0 fs/overlayfs/util.c:24 ovl_setattr+0xdd/0x8b0 fs/overlayfs/inode.c:30 notify_change+0xad9/0xfb0 fs/attr.c:334 do_truncate+0x158/0x220 fs/open.c:63 handle_truncate fs/namei.c:3006 [inline] do_last fs/namei.c:3422 [inline] path_openat+0x2d6a/0x46e0 fs/namei.c:3533 do_filp_open+0x1a1/0x280 fs/namei.c:3563 do_sys_open+0x3fe/0x5d0 fs/open.c:1069 __do_sys_openat fs/open.c:1096 [inline] __se_sys_openat fs/open.c:1090 [inline] __x64_sys_openat+0x9d/0x100 fs/open.c:1090 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&ovl_i_mutex_key[depth]){+.+.}: check_prevs_add kernel/locking/lockdep.c:2333 [inline] validate_chain kernel/locking/lockdep.c:2714 [inline] __lock_acquire+0x239c/0x3fb0 kernel/locking/lockdep.c:3701 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4211 down_write+0x38/0x90 kernel/locking/rwsem.c:70 inode_lock include/linux/fs.h:772 [inline] ovl_write_iter+0x148/0xc20 fs/overlayfs/file.c:231 call_write_iter include/linux/fs.h:1866 [inline] new_sync_write+0x4c7/0x760 fs/read_write.c:474 __vfs_write+0xe4/0x110 fs/read_write.c:487 __kernel_write+0x110/0x3b0 fs/read_write.c:506 do_acct_process+0xd37/0x1150 kernel/acct.c:520 slow_acct_process kernel/acct.c:579 [inline] acct_process+0x568/0x61e kernel/acct.c:605 do_exit+0x17bd/0x2fa0 kernel/exit.c:866 do_group_exit+0x135/0x370 kernel/exit.c:980 __do_sys_exit_group kernel/exit.c:991 [inline] __se_sys_exit_group kernel/exit.c:989 [inline] __x64_sys_exit_group+0x44/0x50 kernel/exit.c:989 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Chain exists of: &ovl_i_mutex_key[depth] --> sb_writers#4 --> &acct->lock#2 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&acct->lock#2); lock(sb_writers#4); lock(&acct->lock#2); lock(&ovl_i_mutex_key[depth]); *** DEADLOCK *** 2 locks held by syz-executor.3/12811: #0: 00000000d6a9923f (&acct->lock#2){+.+.}, at: acct_get kernel/acct.c:161 [inline] #0: 00000000d6a9923f (&acct->lock#2){+.+.}, at: slow_acct_process kernel/acct.c:577 [inline] #0: 00000000d6a9923f (&acct->lock#2){+.+.}, at: acct_process+0x2e5/0x61e kernel/acct.c:605 #1: 00000000abdcc0b7 (sb_writers#16){.+.+}, at: file_start_write_trylock include/linux/fs.h:2832 [inline] #1: 00000000abdcc0b7 (sb_writers#16){.+.+}, at: do_acct_process+0xf37/0x1150 kernel/acct.c:517 stack backtrace: CPU: 1 PID: 12811 Comm: syz-executor.3 Not tainted 5.1.0-rc6+ #83 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+0x172/0x1f0 lib/dump_stack.c:113 print_circular_bug.isra.0.cold+0x1cc/0x28f kernel/locking/lockdep.c:1571 check_prev_add.constprop.0+0xf11/0x23c0 kernel/locking/lockdep.c:2220 check_prevs_add kernel/locking/lockdep.c:2333 [inline] validate_chain kernel/locking/lockdep.c:2714 [inline] __lock_acquire+0x239c/0x3fb0 kernel/locking/lockdep.c:3701 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4211 down_write+0x38/0x90 kernel/locking/rwsem.c:70 inode_lock include/linux/fs.h:772 [inline] ovl_write_iter+0x148/0xc20 fs/overlayfs/file.c:231 call_write_iter include/linux/fs.h:1866 [inline] new_sync_write+0x4c7/0x760 fs/read_write.c:474 __vfs_write+0xe4/0x110 fs/read_write.c:487 __kernel_write+0x110/0x3b0 fs/read_write.c:506 do_acct_process+0xd37/0x1150 kernel/acct.c:520 slow_acct_process kernel/acct.c:579 [inline] acct_process+0x568/0x61e kernel/acct.c:605 do_exit+0x17bd/0x2fa0 kernel/exit.c:866 do_group_exit+0x135/0x370 kernel/exit.c:980 __do_sys_exit_group kernel/exit.c:991 [inline] __se_sys_exit_group kernel/exit.c:989 [inline] __x64_sys_exit_group+0x44/0x50 kernel/exit.c:989 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x458da9 Code: ad b8 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 b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffda8f87858 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 000000000000001e RCX: 0000000000458da9 RDX: 0000000000412b61 RSI: fffffffffffffff7 RDI: 0000000000000000 RBP: 0000000000000000 R08: 00000000b334236f R09: 00007ffda8f878b0 R10: ffffffff8100a19c R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffda8f878b0 R14: 0000000000000000 R15: 00007ffda8f878c0