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[209.132.180.67]) by mx.google.com with ESMTP id j13si11715566pgi.227.2018.11.19.04.09.13; Mon, 19 Nov 2018 04:09:28 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728736AbeKSWaz (ORCPT + 99 others); Mon, 19 Nov 2018 17:30:55 -0500 Received: from ms01.santannapisa.it ([193.205.80.98]:30632 "EHLO mail.santannapisa.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728594AbeKSWaz (ORCPT ); Mon, 19 Nov 2018 17:30:55 -0500 Received: from [10.30.3.226] (account l.abeni@santannapisa.it HELO luca64) by santannapisa.it (CommuniGate Pro SMTP 6.1.11) with ESMTPSA id 134509696; Mon, 19 Nov 2018 13:07:24 +0100 Date: Mon, 19 Nov 2018 13:07:18 +0100 From: luca abeni To: Thomas Gleixner Cc: syzbot , Borislav Petkov , "H. Peter Anvin" , LKML , Andy Lutomirski , mingo@redhat.com, syzkaller-bugs@googlegroups.com, x86@kernel.org, Peter Zijlstra , Juri Lelli , Daniel Bristot de Oliveira Subject: Re: WARNING in enqueue_task_dl Message-ID: <20181119130718.69eddf46@luca64> In-Reply-To: References: <000000000000b5e346057af4da06@google.com> Organization: Scuola Superiore S. Anna X-Mailer: Claws Mail 3.17.1 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi all, On Mon, 19 Nov 2018 09:23:03 +0100 (CET) Thomas Gleixner wrote: > Adding scheduler folks > > On Sun, 18 Nov 2018, syzbot wrote: > > > Hello, > > > > syzbot found the following crash on: > > > > HEAD commit: 1ce80e0fe98e Merge tag 'fsnotify_for_v4.20-rc3' of > > git://g.. git tree: upstream > > console output: > > https://syzkaller.appspot.com/x/log.txt?x=14ddbb0b400000 kernel > > config: https://syzkaller.appspot.com/x/.config?x=d86f24333880b605 > > dashboard link: > > https://syzkaller.appspot.com/bug?extid=119ba87189432ead09b4 > > compiler: gcc (GCC) 8.0.1 20180413 (experimental) syz > > repro: > > https://syzkaller.appspot.com/x/repro.syz?x=13e9e015400000 > > > > IMPORTANT: if you fix the bug, please add the following tag to the > > commit: Reported-by: > > syzbot+119ba87189432ead09b4@syzkaller.appspotmail.com > > > > IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready > > IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready > > 8021q: adding VLAN 0 to HW filter on device team0 > > hrtimer: interrupt took 33411 ns > > sched: DL replenish lagged too much > > WARNING: CPU: 1 PID: 6351 at kernel/sched/deadline.c:628 > > enqueue_task_dl+0x22da/0x38a0 kernel/sched/deadline.c:1504 Here, it looks like a task is invoking sched_setattr() to become SCHED_DEADLINE when dl_boosted is set... Is this possible / correct? If this (sched_setattr() with dl_boosted set) should not be possible, then we have a bug that we need to investigate... Otherwise, I suspect we can just remove the WARN_ON at line 628 of deadline.c Luca > > PM: Basic memory bitmaps freed > > Kernel panic - not syncing: panic_on_warn set ... > > CPU: 1 PID: 6351 Comm: syz-executor0 Not tainted 4.20.0-rc2+ #338 > > 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+0x244/0x39d lib/dump_stack.c:113 > > panic+0x2ad/0x55c kernel/panic.c:188 > > __warn.cold.8+0x20/0x45 kernel/panic.c:540 > > report_bug+0x254/0x2d0 lib/bug.c:186 > > fixup_bug arch/x86/kernel/traps.c:178 [inline] > > do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:271 > > do_invalid_op+0x36/0x40 arch/x86/kernel/traps.c:290 > > invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:969 > > RIP: 0010:enqueue_task_dl+0x22da/0x38a0 kernel/sched/deadline.c:1504 > > Code: ff 48 8b 8d c8 fe ff ff 48 c1 e6 2a 4c 8b 9d d0 fe ff ff 8b > > 95 d8 fe ff ff 48 8b 85 e0 fe ff ff e9 16 e4 ff ff e8 16 d0 ea ff > > <0f> 0b e9 17 f1 ff ff 48 8b bd e8 fe ff ff 4c 89 95 c8 fe ff ff 48 > > RSP: 0018:ffff8881ba39fa18 EFLAGS: 00010002 > > RAX: 0000000000000000 RBX: ffff8881b9d6c000 RCX: ffff8881b9d6c278 > > RDX: ffff8881b9d6c03c RSI: 0000000000000002 RDI: ffff8881daf2d710 > > RBP: ffff8881ba39fb78 R08: 0000000000000001 R09: ffff8881daf00000 > > R10: 0000001a4d4f1987 R11: ffff8881daf2db3b R12: 1ffff11037473f4e > > R13: ffff8881b9d6c2cc R14: ffff8881daf2ccc0 R15: ffff8881daf2ccc0 > > enqueue_task+0x184/0x390 kernel/sched/core.c:730 > > __sched_setscheduler+0xe99/0x2190 kernel/sched/core.c:4336 > > sched_setattr kernel/sched/core.c:4394 [inline] > > __do_sys_sched_setattr kernel/sched/core.c:4570 [inline] > > __se_sys_sched_setattr kernel/sched/core.c:4549 [inline] > > __x64_sys_sched_setattr+0x1b2/0x2f0 kernel/sched/core.c:4549 > > do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 > > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > RIP: 0033:0x457569 > > Code: fd b3 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 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 > > RSP: 002b:00007f05ce0a2c78 EFLAGS: 00000246 ORIG_RAX: > > 000000000000013a RAX: ffffffffffffffda RBX: 0000000000000003 RCX: > > 0000000000457569 RDX: 0000000000000000 RSI: 0000000020000000 RDI: > > 0000000000000000 RBP: 000000000072bfa0 R08: 0000000000000000 R09: > > 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: > > 00007f05ce0a36d4 R13: 00000000004c369f R14: 00000000004d5730 R15: > > 00000000ffffffff > > > > ====================================================== > > WARNING: possible circular locking dependency detected > > 4.20.0-rc2+ #338 Not tainted > > ------------------------------------------------------ > > syz-executor0/6351 is trying to acquire lock: > > 00000000b2b97155 ((console_sem).lock){-.-.}, at: > > down_trylock+0x13/0x70 kernel/locking/semaphore.c:136 > > > > but task is already holding lock: > > 000000004cd5557e (&rq->lock){-.-.}, at: task_rq_lock+0xc5/0x2a0 > > kernel/sched/core.c:99 > > > > which lock already depends on the new lock. > > > > > > the existing dependency chain (in reverse order) is: > > > > -> #2 (&rq->lock){-.-.}: > > __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] > > _raw_spin_lock+0x2d/0x40 kernel/locking/spinlock.c:144 > > rq_lock kernel/sched/sched.h:1126 [inline] > > task_fork_fair+0xb0/0x6d0 kernel/sched/fair.c:9768 > > sched_fork+0x443/0xba0 kernel/sched/core.c:2359 > > copy_process+0x25b8/0x87a0 kernel/fork.c:1887 > > _do_fork+0x1cb/0x11d0 kernel/fork.c:2216 > > kernel_thread+0x34/0x40 kernel/fork.c:2275 > > rest_init+0x28/0x372 init/main.c:409 > > arch_call_rest_init+0xe/0x1b > > start_kernel+0x9f0/0xa2b init/main.c:745 > > x86_64_start_reservations+0x2e/0x30 > > arch/x86/kernel/head64.c:472 x86_64_start_kernel+0x76/0x79 > > arch/x86/kernel/head64.c:451 secondary_startup_64+0xa4/0xb0 > > arch/x86/kernel/head_64.S:243 > > -> #1 (&p->pi_lock){-.-.}: > > __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 > > [inline] _raw_spin_lock_irqsave+0x99/0xd0 > > kernel/locking/spinlock.c:152 try_to_wake_up+0xdc/0x1490 > > kernel/sched/core.c:1965 wake_up_process+0x10/0x20 > > kernel/sched/core.c:2129 __up.isra.1+0x1c0/0x2a0 > > kernel/locking/semaphore.c:262 up+0x13c/0x1c0 > > kernel/locking/semaphore.c:187 __up_console_sem+0xbe/0x1b0 > > kernel/printk/printk.c:236 console_unlock+0x811/0x1190 > > kernel/printk/printk.c:2432 do_con_write+0x1356/0x23b0 > > drivers/tty/vt/vt.c:2767 con_write+0x25/0xc0 > > drivers/tty/vt/vt.c:3116 process_output_block > > drivers/tty/n_tty.c:593 [inline] n_tty_write+0x6c1/0x11a0 > > drivers/tty/n_tty.c:2331 do_tty_write drivers/tty/tty_io.c:959 > > [inline] tty_write+0x3f1/0x880 drivers/tty/tty_io.c:1043 > > __vfs_write+0x119/0x9f0 fs/read_write.c:485 > > vfs_write+0x1fc/0x560 fs/read_write.c:549 > > ksys_write+0x101/0x260 fs/read_write.c:598 > > __do_sys_write fs/read_write.c:610 [inline] > > __se_sys_write fs/read_write.c:607 [inline] > > __x64_sys_write+0x73/0xb0 fs/read_write.c:607 > > do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 > > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > > > -> #0 ((console_sem).lock){-.-.}: > > lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844 > > __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 > > [inline] _raw_spin_lock_irqsave+0x99/0xd0 > > kernel/locking/spinlock.c:152 down_trylock+0x13/0x70 > > kernel/locking/semaphore.c:136 > > __down_trylock_console_sem+0xae/0x1f0 kernel/printk/printk.c:219 > > console_trylock+0x15/0xa0 kernel/printk/printk.c:2247 > > console_trylock_spinning kernel/printk/printk.c:1653 [inline] > > vprintk_emit+0x372/0x990 kernel/printk/printk.c:1921 > > vprintk_default+0x28/0x30 kernel/printk/printk.c:1964 > > vprintk_func+0x7e/0x181 kernel/printk/printk_safe.c:398 > > printk+0xa7/0xcf kernel/printk/printk.c:1997 __warn+0x9e/0x1d0 > > kernel/panic.c:522 report_bug+0x254/0x2d0 lib/bug.c:186 > > fixup_bug arch/x86/kernel/traps.c:178 [inline] > > do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:271 > > do_invalid_op+0x36/0x40 arch/x86/kernel/traps.c:290 > > invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:969 > > enqueue_task_dl+0x22da/0x38a0 kernel/sched/deadline.c:1504 > > enqueue_task+0x184/0x390 kernel/sched/core.c:730 > > __sched_setscheduler+0xe99/0x2190 kernel/sched/core.c:4336 > > sched_setattr kernel/sched/core.c:4394 [inline] > > __do_sys_sched_setattr kernel/sched/core.c:4570 [inline] > > __se_sys_sched_setattr kernel/sched/core.c:4549 [inline] > > __x64_sys_sched_setattr+0x1b2/0x2f0 kernel/sched/core.c:4549 > > do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 > > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > > > other info that might help us debug this: > > > > Chain exists of: > > (console_sem).lock --> &p->pi_lock --> &rq->lock > > > > Possible unsafe locking scenario: > > > > CPU0 CPU1 > > ---- ---- > > lock(&rq->lock); > > lock(&p->pi_lock); > > lock(&rq->lock); > > lock((console_sem).lock); > > > > *** DEADLOCK *** > > > > 3 locks held by syz-executor0/6351: > > #0: 000000001a0356c1 (rcu_read_lock){....}, at: > > __do_sys_sched_setattr kernel/sched/core.c:4563 [inline] > > #0: 000000001a0356c1 (rcu_read_lock){....}, at: > > __se_sys_sched_setattr kernel/sched/core.c:4549 [inline] > > #0: 000000001a0356c1 (rcu_read_lock){....}, at: > > __x64_sys_sched_setattr+0x146/0x2f0 kernel/sched/core.c:4549 > > #1: 000000000b71b478 (&p->pi_lock){-.-.}, at: > > task_rq_lock+0x62/0x2a0 kernel/sched/core.c:97 > > #2: 000000004cd5557e (&rq->lock){-.-.}, at: task_rq_lock+0xc5/0x2a0 > > kernel/sched/core.c:99 > > > > stack backtrace: > > CPU: 1 PID: 6351 Comm: syz-executor0 Not tainted 4.20.0-rc2+ #338 > > 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+0x244/0x39d lib/dump_stack.c:113 > > print_circular_bug.isra.35.cold.54+0x1bd/0x27d > > kernel/locking/lockdep.c:1221 check_prev_add > > kernel/locking/lockdep.c:1863 [inline] check_prevs_add > > kernel/locking/lockdep.c:1976 [inline] validate_chain > > kernel/locking/lockdep.c:2347 [inline] __lock_acquire+0x3399/0x4c20 > > kernel/locking/lockdep.c:3341 lock_acquire+0x1ed/0x520 > > kernel/locking/lockdep.c:3844 __raw_spin_lock_irqsave > > include/linux/spinlock_api_smp.h:110 [inline] > > _raw_spin_lock_irqsave+0x99/0xd0 kernel/locking/spinlock.c:152 > > down_trylock+0x13/0x70 kernel/locking/semaphore.c:136 > > __down_trylock_console_sem+0xae/0x1f0 kernel/printk/printk.c:219 > > console_trylock+0x15/0xa0 kernel/printk/printk.c:2247 > > console_trylock_spinning kernel/printk/printk.c:1653 [inline] > > vprintk_emit+0x372/0x990 kernel/printk/printk.c:1921 > > vprintk_default+0x28/0x30 kernel/printk/printk.c:1964 > > vprintk_func+0x7e/0x181 kernel/printk/printk_safe.c:398 > > printk+0xa7/0xcf kernel/printk/printk.c:1997 __warn+0x9e/0x1d0 > > kernel/panic.c:522 report_bug+0x254/0x2d0 lib/bug.c:186 > > fixup_bug arch/x86/kernel/traps.c:178 [inline] > > do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:271 > > do_invalid_op+0x36/0x40 arch/x86/kernel/traps.c:290 > > invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:969 > > RIP: 0010:enqueue_task_dl+0x22da/0x38a0 kernel/sched/deadline.c:1504 > > Code: ff 48 8b 8d c8 fe ff ff 48 c1 e6 2a 4c 8b 9d d0 fe ff ff 8b > > 95 d8 fe ff ff 48 8b 85 e0 fe ff ff e9 16 e4 ff ff e8 16 d0 ea ff > > <0f> 0b e9 17 f1 ff ff 48 8b bd e8 fe ff ff 4c 89 95 c8 fe ff ff 48 > > RSP: 0018:ffff8881ba39fa18 EFLAGS: 00010002 > > RAX: 0000000000000000 RBX: ffff8881b9d6c000 RCX: ffff8881b9d6c278 > > RDX: ffff8881b9d6c03c RSI: 0000000000000002 RDI: ffff8881daf2d710 > > RBP: ffff8881ba39fb78 R08: 0000000000000001 R09: ffff8881daf00000 > > R10: 0000001a4d4f1987 R11: ffff8881daf2db3b R12: 1ffff11037473f4e > > R13: ffff8881b9d6c2cc R14: ffff8881daf2ccc0 R15: ffff8881daf2ccc0 > > enqueue_task+0x184/0x390 kernel/sched/core.c:730 > > __sched_setscheduler+0xe99/0x2190 kernel/sched/core.c:4336 > > sched_setattr kernel/sched/core.c:4394 [inline] > > __do_sys_sched_setattr kernel/sched/core.c:4570 [inline] > > __se_sys_sched_setattr kernel/sched/core.c:4549 [inline] > > __x64_sys_sched_setattr+0x1b2/0x2f0 kernel/sched/core.c:4549 > > do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 > > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > RIP: 0033:0x457569 > > Code: fd b3 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 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 > > RSP: 002b:00007f05ce0a2c78 EFLAGS: 00000246 ORIG_RAX: > > 000000000000013a RAX: ffffffffffffffda RBX: 0000000000000003 RCX: > > 0000000000457569 RDX: 0000000000000000 RSI: 0000000020000000 RDI: > > 0000000000000000 RBP: 000000000072bfa0 R08: 0000000000000000 R09: > > 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: > > 00007f05ce0a36d4 R13: 00000000004c369f R14: 00000000004d5730 R15: > > 00000000ffffffff Shutting down cpus with NMI > > Kernel Offset: disabled > > Rebooting in 86400 seconds.. > > > > > > --- > > This bug is generated by a bot. It may contain errors. > > See https://goo.gl/tpsmEJ for more information about syzbot. > > syzbot engineers can be reached at syzkaller@googlegroups.com. > > > > syzbot will keep track of this bug report. See: > > https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate > > with syzbot. syzbot can test patches for this bug, for details see: > > https://goo.gl/tpsmEJ#testing-patches