====================================================== WARNING: possible circular locking dependency detected 5.1.0-rc6+ #85 Not tainted ------------------------------------------------------ syz-executor.3/22966 is trying to acquire lock: 00000000854ce961 (&acct->lock#2){+.+.}, at: acct_pin_kill+0x27/0x100 kernel/acct.c:173 but task is already holding lock: 00000000f1bdc742 (sb_writers#3){.+.+}, at: sb_start_write include/linux/fs.h:1621 [inline] 00000000f1bdc742 (sb_writers#3){.+.+}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:358 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (sb_writers#3){.+.+}: 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_link+0x32/0x24f fs/overlayfs/dir.c:672 vfs_link+0x7a4/0xbc0 fs/namei.c:4239 do_linkat+0x550/0x770 fs/namei.c:4307 __do_sys_link fs/namei.c:4336 [inline] __se_sys_link fs/namei.c:4334 [inline] __x64_sys_link+0x61/0x80 fs/namei.c:4334 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #1 (&ovl_i_mutex_key[depth]){+.+.}: 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 get_signal+0x399/0x1d50 kernel/signal.c:2577 do_signal+0x87/0x1940 arch/x86/kernel/signal.c:816 exit_to_usermode_loop+0x244/0x2c0 arch/x86/entry/common.c:162 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline] syscall_return_slowpath arch/x86/entry/common.c:268 [inline] do_syscall_64+0x52d/0x610 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&acct->lock#2){+.+.}: 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 __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 other info that might help us debug this: Chain exists of: &acct->lock#2 --> &ovl_i_mutex_key[depth] --> sb_writers#3 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(sb_writers#3); lock(&ovl_i_mutex_key[depth]); lock(sb_writers#3); lock(&acct->lock#2); *** DEADLOCK *** 2 locks held by syz-executor.3/22966: #0: 00000000c9cb5ec6 (acct_on_mutex){+.+.}, at: __do_sys_acct kernel/acct.c:285 [inline] #0: 00000000c9cb5ec6 (acct_on_mutex){+.+.}, at: __se_sys_acct kernel/acct.c:273 [inline] #0: 00000000c9cb5ec6 (acct_on_mutex){+.+.}, at: __x64_sys_acct+0xa6/0x200 kernel/acct.c:273 #1: 00000000f1bdc742 (sb_writers#3){.+.+}, at: sb_start_write include/linux/fs.h:1621 [inline] #1: 00000000f1bdc742 (sb_writers#3){.+.+}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:358 stack backtrace: CPU: 0 PID: 22966 Comm: syz-executor.3 Not tainted 5.1.0-rc6+ #85 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 __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 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:00007fa9081c8c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a3 RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000458da9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000080 RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fa9081c96d4 R13: 00000000004becd2 R14: 00000000004cfa50 R15: 00000000ffffffff Process accounting resumed