On Tue, Mar 21, 2017 at 08:25:39PM +0100, Thomas Gleixner wrote: > > I just hit this while fuzzing.. > > > > general protection fault: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC > > CPU: 2 PID: 0 Comm: swapper/2 Not tainted 4.11.0-rc2-think+ #1 > > task: ffff88017f0ed440 task.stack: ffffc90000094000 > > RIP: 0010:run_timer_softirq+0x15f/0x700 > > RSP: 0018:ffff880507c03ec8 EFLAGS: 00010086 > > RAX: dead000000000200 RBX: ffff880507dd0d00 RCX: 0000000000000002 > > RDX: ffff880507c03ed0 RSI: 00000000ffffffff RDI: ffffffff8204b3a0 > > RBP: ffff880507c03f48 R08: ffff880507dd12d0 R09: ffff880507c03ed8 > > R10: ffff880507dd0db0 R11: 0000000000000000 R12: ffffffff8215cc38 > > R13: ffff880507c03ed0 R14: ffffffff82005188 R15: ffff8804b55491a8 > > FS: 0000000000000000(0000) GS:ffff880507c00000(0000) > > knlGS:0000000000000000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > CR2: 0000000000000004 CR3: 0000000005011000 CR4: 00000000001406e0 > > Call Trace: > > <IRQ> > > ? clockevents_program_event+0x47/0x120 > > __do_softirq+0xbf/0x5b1 > > irq_exit+0xb5/0xc0 > > smp_apic_timer_interrupt+0x3d/0x50 > > apic_timer_interrupt+0x97/0xa0 > > RIP: 0010:cpuidle_enter_state+0x12e/0x400 > > RSP: 0018:ffffc90000097e40 EFLAGS: 00000202 > > [CONT START] ORIG_RAX: ffffffffffffff10 > > RAX: ffff88017f0ed440 RBX: ffffe8ffffa03cc8 RCX: 0000000000000001 > > RDX: 20c49ba5e353f7cf RSI: 0000000000000001 RDI: ffff88017f0ed440 > > RBP: ffffc90000097e80 R08: 00000000ffffffff R09: 0000000000000008 > > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000005 > > R13: ffffffff820b9338 R14: 0000000000000005 R15: ffffffff820b9320 > > </IRQ> > > cpuidle_enter+0x17/0x20 > > call_cpuidle+0x23/0x40 > > do_idle+0xfb/0x200 > > cpu_startup_entry+0x71/0x80 > > start_secondary+0x16a/0x210 > > start_cpu+0x14/0x14 > > Code: 8b 05 ce 1b ef 7e 83 f8 03 0f 87 4e 01 00 00 89 c0 49 0f a3 04 24 0f > > 82 0a 01 00 00 49 8b 07 49 8b 57 08 48 85 c0 48 89 02 74 04 <48> 89 50 08 > > 41 f6 47 2a 20 49 c7 47 08 00 00 00 00 48 89 df 48 > > The timer which expires has timer->entry.next == POISON2 ! > > it's a classic list corruption. The > bad news is that there is no trace of the culprit because that happens when > some other timer expires after some random amount of time. > > If that is reproducible, then please enable debugobjects. That should > pinpoint the culprit.
It's net/smc. This recently had a similar bug with workqueues. (https://marc.info/?l=linux-kernel&m=148821582909541) fixed by 637fdbae60d6cb9f6e963c1079d7e0445c86ff7d so it's probably unsurprising that there are similar issues. WARNING: CPU: 0 PID: 2430 at lib/debugobjects.c:289 debug_print_object+0x87/0xb0 ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x20 CPU: 0 PID: 2430 Comm: trinity-c4 Not tainted 4.11.0-rc3-think+ #3 Call Trace: dump_stack+0x68/0x93 __warn+0xcb/0xf0 warn_slowpath_fmt+0x5f/0x80 ? debug_check_no_obj_freed+0xd9/0x260 debug_print_object+0x87/0xb0 ? work_on_cpu+0xd0/0xd0 debug_check_no_obj_freed+0x219/0x260 ? __sk_destruct+0x10d/0x1c0 kmem_cache_free+0x9f/0x370 __sk_destruct+0x10d/0x1c0 sk_destruct+0x20/0x30 __sk_free+0x43/0xa0 sk_free+0x18/0x20 smc_release+0x100/0x1a0 [smc] sock_release+0x1f/0x80 sock_close+0x12/0x20 __fput+0xf3/0x200 ____fput+0xe/0x10 task_work_run+0x85/0xb0 do_exit+0x331/0xd70 __secure_computing+0x9c/0xa0 syscall_trace_enter+0xd1/0x3d0 do_syscall_64+0x15f/0x1d0 entry_SYSCALL64_slow_path+0x25/0x25 RIP: 0033:0x7f535f4b19e7 RSP: 002b:00007fff1a0f40e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000008 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007f535f4b19e7 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004 RBP: 0000000000000000 R08: 00007f535fb8b000 R09: 00c17c2740a303e4 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff1a0f40f5 R13: 00007f535fb60048 R14: 00007f535fb83ad8 R15: 00007f535fb60000 ---[ end trace ee67155de15508db ]--- ====================================================== [ INFO: possible circular locking dependency detected ] 4.11.0-rc3-think+ #3 Not tainted ------------------------------------------------------- trinity-c4/2430 is trying to acquire lock: ( (console_sem).lock ){-.-...} , at: [<ffffffff810e6be4>] down_trylock+0x14/0x40 but task is already holding lock: ( &obj_hash[i].lock ){-.-.-.} , at: [<ffffffff81515689>] debug_check_no_obj_freed+0xd9/0x260 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 ( &obj_hash[i].lock ){-.-.-.} : lock_acquire+0x102/0x260 _raw_spin_lock_irqsave+0x4c/0x90 __debug_object_init+0x79/0x460 debug_object_init+0x16/0x20 hrtimer_init+0x25/0x1d0 init_dl_task_timer+0x20/0x30 __sched_fork.isra.91+0x9c/0x140 init_idle+0x51/0x240 sched_init+0x4cd/0x547 start_kernel+0x246/0x45d x86_64_start_reservations+0x2a/0x2c x86_64_start_kernel+0x178/0x18b verify_cpu+0x0/0xf1 -> #2 ( &rq->lock ){-.-.-.} : lock_acquire+0x102/0x260 _raw_spin_lock+0x41/0x80 task_fork_fair+0x3a/0x100 sched_fork+0x12b/0x2e0 copy_process.part.39+0x65b/0x2080 _do_fork+0xf6/0x770 kernel_thread+0x29/0x30 rest_init+0x22/0x140 start_kernel+0x43c/0x45d x86_64_start_reservations+0x2a/0x2c x86_64_start_kernel+0x178/0x18b verify_cpu+0x0/0xf1 -> #1 ( &p->pi_lock ){-.-.-.} : lock_acquire+0x102/0x260 _raw_spin_lock_irqsave+0x4c/0x90 try_to_wake_up+0x40/0x6e0 wake_up_process+0x15/0x20 __up.isra.0+0x4c/0x50 up+0x46/0x50 __up_console_sem+0x37/0x60 console_unlock+0x275/0x5e0 do_con_write.part.22+0x761/0xa20 con_write+0x5c/0x60 n_tty_write+0x1bf/0x490 tty_write+0x1b3/0x320 redirected_tty_write+0x92/0xb0 __do_readv_writev+0x2e5/0x380 do_readv_writev+0x7c/0xc0 vfs_writev+0x3f/0x50 do_writev+0x64/0x100 SyS_writev+0x10/0x20 do_syscall_64+0x66/0x1d0 return_from_SYSCALL_64+0x0/0x7a -> #0 ( (console_sem).lock ){-.-...} : __lock_acquire+0x1134/0x12b0 lock_acquire+0x102/0x260 _raw_spin_lock_irqsave+0x4c/0x90 down_trylock+0x14/0x40 __down_trylock_console_sem+0x2f/0xa0 console_trylock+0x16/0x90 vprintk_emit+0x2ac/0x390 vprintk_default+0x29/0x50 vprintk_func+0x25/0x80 printk+0x52/0x6e __warn+0x39/0xf0 warn_slowpath_fmt+0x5f/0x80 debug_print_object+0x87/0xb0 debug_check_no_obj_freed+0x219/0x260 kmem_cache_free+0x9f/0x370 __sk_destruct+0x10d/0x1c0 sk_destruct+0x20/0x30 __sk_free+0x43/0xa0 sk_free+0x18/0x20 smc_release+0x100/0x1a0 [smc] sock_release+0x1f/0x80 sock_close+0x12/0x20 __fput+0xf3/0x200 ____fput+0xe/0x10 task_work_run+0x85/0xb0 do_exit+0x331/0xd70 __secure_computing+0x9c/0xa0 syscall_trace_enter+0xd1/0x3d0 do_syscall_64+0x15f/0x1d0 return_from_SYSCALL_64+0x0/0x7a other info that might help us debug this: Chain exists of: (console_sem).lock --> &rq->lock --> &obj_hash[i].lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock( &obj_hash[i].lock ); lock( &rq->lock ); lock( &obj_hash[i].lock ); lock( (console_sem).lock ); *** DEADLOCK *** 1 lock held by trinity-c4/2430: #0: ( &obj_hash[i].lock ){-.-.-.} , at: [<ffffffff81515689>] debug_check_no_obj_freed+0xd9/0x260 stack backtrace: CPU: 0 PID: 2430 Comm: trinity-c4 Not tainted 4.11.0-rc3-think+ #3 Call Trace: dump_stack+0x68/0x93 print_circular_bug+0x1be/0x210 __lock_acquire+0x1134/0x12b0 lock_acquire+0x102/0x260 ? down_trylock+0x14/0x40 _raw_spin_lock_irqsave+0x4c/0x90 ? down_trylock+0x14/0x40 ? vprintk_emit+0x2ac/0x390 down_trylock+0x14/0x40 __down_trylock_console_sem+0x2f/0xa0 console_trylock+0x16/0x90 ? trace_hardirqs_off+0xd/0x10 vprintk_emit+0x2ac/0x390 ? debug_print_object+0x87/0xb0 vprintk_default+0x29/0x50 vprintk_func+0x25/0x80 ? unwind_next_frame+0x93/0x240 printk+0x52/0x6e ? debug_print_object+0x87/0xb0 __warn+0x39/0xf0 warn_slowpath_fmt+0x5f/0x80 ? debug_check_no_obj_freed+0xd9/0x260 debug_print_object+0x87/0xb0 ? work_on_cpu+0xd0/0xd0 debug_check_no_obj_freed+0x219/0x260 ? __sk_destruct+0x10d/0x1c0 kmem_cache_free+0x9f/0x370 __sk_destruct+0x10d/0x1c0 sk_destruct+0x20/0x30 __sk_free+0x43/0xa0 sk_free+0x18/0x20 smc_release+0x100/0x1a0 [smc] sock_release+0x1f/0x80 sock_close+0x12/0x20 __fput+0xf3/0x200 ____fput+0xe/0x10 task_work_run+0x85/0xb0 do_exit+0x331/0xd70 __secure_computing+0x9c/0xa0 syscall_trace_enter+0xd1/0x3d0 do_syscall_64+0x15f/0x1d0 entry_SYSCALL64_slow_path+0x25/0x25 RIP: 0033:0x7f535f4b19e7 RSP: 002b:00007fff1a0f40e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000008 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007f535f4b19e7 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004 RBP: 0000000000000000 R08: 00007f535fb8b000 R09: 00c17c2740a303e4 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff1a0f40f5 R13: 00007f535fb60048 R14: 00007f535fb83ad8 R15: 00007f535fb60000
