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[209.132.180.67]) by mx.google.com with ESMTP id m187si51696119pfm.51.2019.01.02.03.57.37; Wed, 02 Jan 2019 03:57:52 -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 S1729261AbfABKPa (ORCPT + 99 others); Wed, 2 Jan 2019 05:15:30 -0500 Received: from ms01.santannapisa.it ([193.205.80.98]:36572 "EHLO mail.santannapisa.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726499AbfABKPa (ORCPT ); Wed, 2 Jan 2019 05:15:30 -0500 X-Greylist: delayed 3601 seconds by postgrey-1.27 at vger.kernel.org; Wed, 02 Jan 2019 05:15:27 EST Received: from [151.40.186.16] (account l.abeni@santannapisa.it HELO sweethome) by santannapisa.it (CommuniGate Pro SMTP 6.1.11) with ESMTPSA id 135439519; Wed, 02 Jan 2019 10:15:24 +0100 Date: Wed, 2 Jan 2019 10:15:18 +0100 From: luca abeni To: juri.lelli@redhat.com Cc: syzbot , bp@alien8.de, bristot@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, luto@kernel.org, mingo@redhat.com, peterz@infradead.org, syzkaller-bugs@googlegroups.com, tglx@linutronix.de, x86@kernel.org Subject: Re: WARNING in enqueue_task_dl Message-ID: <20190102101518.1d21ba0c@sweethome> In-Reply-To: <0000000000001f4fee057e52b284@google.com> References: <000000000000b5e346057af4da06@google.com> <0000000000001f4fee057e52b284@google.com> X-Mailer: Claws Mail 3.16.0 (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, (and, happy new year to everyone!) this looks similar to a bug we have seen some time ago (a task switching from SCHED_OTHER to SCHED_DEADLINE while inheriting a deadline from a SCHED_DEADLINE task triggers the warning)... Juri, I think you found a fix for such a bug; has it been committed? Thanks, Luca On Mon, 31 Dec 2018 07:02:04 -0800 syzbot wrote: > syzbot has found a reproducer for the following crash on: > > HEAD commit: 195303136f19 Merge tag 'kconfig-v4.21-2' of > git://git.kern.. git tree: upstream > console output: > https://syzkaller.appspot.com/x/log.txt?x=118af84b400000 kernel > config: https://syzkaller.appspot.com/x/.config?x=76d28549be7c27cf > dashboard link: > https://syzkaller.appspot.com/bug?extid=119ba87189432ead09b4 > compiler: gcc (GCC) 9.0.0 20181231 (experimental) syz > repro: > https://syzkaller.appspot.com/x/repro.syz?x=10eb7ebf400000 C > reproducer: https://syzkaller.appspot.com/x/repro.c?x=14156d77400000 > > IMPORTANT: if you fix the bug, please add the following tag to the > commit: Reported-by: > syzbot+119ba87189432ead09b4@syzkaller.appspotmail.com > > WARNING: CPU: 0 PID: 9019 at kernel/sched/deadline.c:628 > setup_new_dl_entity kernel/sched/deadline.c:629 [inline] > WARNING: CPU: 0 PID: 9019 at kernel/sched/deadline.c:628 > enqueue_dl_entity kernel/sched/deadline.c:1429 [inline] > WARNING: CPU: 0 PID: 9019 at kernel/sched/deadline.c:628 > enqueue_task_dl+0x2355/0x3dc0 kernel/sched/deadline.c:1500 > Kernel panic - not syncing: panic_on_warn set ... > CPU: 0 PID: 9019 Comm: syz-executor280 Not tainted 4.20.0+ #1 > 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+0x1db/0x2d0 lib/dump_stack.c:113 > panic+0x2cb/0x589 kernel/panic.c:189 > __warn.cold+0x20/0x4b kernel/panic.c:544 > report_bug+0x263/0x2b0 lib/bug.c:186 > fixup_bug arch/x86/kernel/traps.c:178 [inline] > fixup_bug arch/x86/kernel/traps.c:173 [inline] > do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:271 > do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:290 > invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:973 > RIP: 0010:setup_new_dl_entity kernel/sched/deadline.c:628 [inline] > RIP: 0010:enqueue_dl_entity kernel/sched/deadline.c:1429 [inline] > RIP: 0010:enqueue_task_dl+0x2355/0x3dc0 kernel/sched/deadline.c:1500 > Code: 3c 02 00 0f 85 ba 05 00 00 49 8b b5 50 0a 00 00 e9 53 fa ff ff > e8 fb f2 64 00 48 8d 4d d8 e9 48 dd ff ff 0f 0b e9 92 f1 ff ff <0f> > 0b e9 18 f1 ff ff 4c 89 ef 4c 89 95 28 ff ff ff 4c 89 85 30 ff > RSP: 0018:ffff88809eebfaf8 EFLAGS: 00010002 > RAX: 0000000000000002 RBX: 1ffff11013dd7f6a RCX: dffffc0000000000 > RDX: 000000333cf09f75 RSI: 0000000000000004 RDI: ffff8880ae62d850 > RBP: ffff88809eebfbf8 R08: ffff88807fb0a538 R09: ffff88807fb0a2fc > R10: ffff88807fb0a580 R11: ffff8880ae62dc7b R12: ffff88807fb0a2c0 > R13: ffff8880ae62ce00 R14: ffff8880ae62ce00 R15: ffff88807fb0a58c > enqueue_task+0xb9/0x380 kernel/sched/core.c:730 > __sched_setscheduler+0xe32/0x1fe0 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+0x1af/0x2f0 kernel/sched/core.c:4549 > do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > RIP: 0033:0x44c829 > Code: e8 8c d8 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 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 eb c9 fb ff c3 66 2e 0f 1f 84 00 00 00 00 > RSP: 002b:00007f28685e8ce8 EFLAGS: 00000246 ORIG_RAX: 000000000000013a > RAX: ffffffffffffffda RBX: 00000000006e49f8 RCX: 000000000044c829 > RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000000 > RBP: 00000000006e49f0 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006e49fc > R13: 00007ffd1981c8af R14: 00007f28685e99c0 R15: 0000000000000001 > > ====================================================== > WARNING: possible circular locking dependency detected > 4.20.0+ #1 Not tainted > ------------------------------------------------------ > syz-executor280/9019 is trying to acquire lock: > 000000001aef527c ((console_sem).lock){-.-.}, at: > down_trylock+0x13/0x70 kernel/locking/semaphore.c:136 > > but task is already holding lock: > 000000000ba17b09 (&rq->lock){-.-.}, at: task_rq_lock+0xc8/0x290 > 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+0x2f/0x40 kernel/locking/spinlock.c:144 > rq_lock kernel/sched/sched.h:1149 [inline] > task_fork_fair+0xb5/0x7a0 kernel/sched/fair.c:10083 > sched_fork+0x437/0xb90 kernel/sched/core.c:2359 > copy_process+0x1ff6/0x8730 kernel/fork.c:1893 > _do_fork+0x1a9/0x1170 kernel/fork.c:2222 > kernel_thread+0x34/0x40 kernel/fork.c:2281 > rest_init+0x28/0x37b init/main.c:409 > arch_call_rest_init+0xe/0x1b > start_kernel+0x882/0x8bd init/main.c:741 > x86_64_start_reservations+0x29/0x2b > arch/x86/kernel/head64.c:470 x86_64_start_kernel+0x77/0x7b > 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+0x95/0xcd > kernel/locking/spinlock.c:152 try_to_wake_up+0xb9/0x1480 > kernel/sched/core.c:1965 wake_up_process+0x10/0x20 > kernel/sched/core.c:2129 __up.isra.0+0x1c0/0x2a0 > kernel/locking/semaphore.c:262 up+0x13e/0x1c0 > kernel/locking/semaphore.c:187 __up_console_sem+0xb7/0x1c0 > kernel/printk/printk.c:236 console_unlock+0x778/0x11e0 > kernel/printk/printk.c:2426 con_flush_chars drivers/tty/vt/vt.c:3197 > [inline] con_flush_chars drivers/tty/vt/vt.c:3185 [inline] > con_write+0xa2/0xb0 drivers/tty/vt/vt.c:3117 > process_output_block drivers/tty/n_tty.c:593 [inline] > n_tty_write+0x497/0x1220 drivers/tty/n_tty.c:2331 > do_tty_write drivers/tty/tty_io.c:959 [inline] > tty_write+0x45b/0x7a0 drivers/tty/tty_io.c:1043 > __vfs_write+0x116/0xb40 fs/read_write.c:485 > vfs_write+0x20c/0x580 fs/read_write.c:549 > ksys_write+0x105/0x260 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+0x1a3/0x800 arch/x86/entry/common.c:290 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > -> #0 ((console_sem).lock){-.-.}: > lock_acquire+0x1db/0x570 kernel/locking/lockdep.c:3841 > __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 > [inline] _raw_spin_lock_irqsave+0x95/0xcd > kernel/locking/spinlock.c:152 down_trylock+0x13/0x70 > kernel/locking/semaphore.c:136 __down_trylock_console_sem+0xa8/0x210 > kernel/printk/printk.c:219 console_trylock+0x15/0xa0 > kernel/printk/printk.c:2242 console_trylock_spinning > kernel/printk/printk.c:1662 [inline] vprintk_emit+0x351/0x960 > kernel/printk/printk.c:1930 vprintk_default+0x28/0x30 > kernel/printk/printk.c:1958 vprintk_func+0x7e/0x189 > kernel/printk/printk_safe.c:398 printk+0xba/0xed > kernel/printk/printk.c:1991 __warn+0x9e/0x1d0 kernel/panic.c:526 > report_bug+0x263/0x2b0 lib/bug.c:186 > fixup_bug arch/x86/kernel/traps.c:178 [inline] > fixup_bug arch/x86/kernel/traps.c:173 [inline] > do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:271 > do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:290 > invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:973 > setup_new_dl_entity kernel/sched/deadline.c:629 [inline] > enqueue_dl_entity kernel/sched/deadline.c:1429 [inline] > enqueue_task_dl+0x2355/0x3dc0 kernel/sched/deadline.c:1500 > enqueue_task+0xb9/0x380 kernel/sched/core.c:730 > __sched_setscheduler+0xe32/0x1fe0 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+0x1af/0x2f0 kernel/sched/core.c:4549 > do_syscall_64+0x1a3/0x800 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-executor280/9019: > #0: 0000000014b8e16d (rcu_read_lock){....}, at: > __do_sys_sched_setattr kernel/sched/core.c:4563 [inline] > #0: 0000000014b8e16d (rcu_read_lock){....}, at: > __se_sys_sched_setattr kernel/sched/core.c:4549 [inline] > #0: 0000000014b8e16d (rcu_read_lock){....}, at: > __x64_sys_sched_setattr+0x144/0x2f0 kernel/sched/core.c:4549 > #1: 00000000b31ff59d (&p->pi_lock){-.-.}, at: > task_rq_lock+0x6a/0x290 kernel/sched/core.c:97 > #2: 000000000ba17b09 (&rq->lock){-.-.}, at: > task_rq_lock+0xc8/0x290 kernel/sched/core.c:99 > > stack backtrace: > CPU: 0 PID: 9019 Comm: syz-executor280 Not tainted 4.20.0+ #1 > 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+0x1db/0x2d0 lib/dump_stack.c:113 > print_circular_bug.isra.0.cold+0x1cc/0x28f > kernel/locking/lockdep.c:1224 check_prev_add > kernel/locking/lockdep.c:1866 [inline] check_prevs_add > kernel/locking/lockdep.c:1979 [inline] validate_chain > kernel/locking/lockdep.c:2350 [inline] __lock_acquire+0x3014/0x4a30 > kernel/locking/lockdep.c:3338 lock_acquire+0x1db/0x570 > kernel/locking/lockdep.c:3841 __raw_spin_lock_irqsave > include/linux/spinlock_api_smp.h:110 [inline] > _raw_spin_lock_irqsave+0x95/0xcd kernel/locking/spinlock.c:152 > down_trylock+0x13/0x70 kernel/locking/semaphore.c:136 > __down_trylock_console_sem+0xa8/0x210 kernel/printk/printk.c:219 > console_trylock+0x15/0xa0 kernel/printk/printk.c:2242 > console_trylock_spinning kernel/printk/printk.c:1662 [inline] > vprintk_emit+0x351/0x960 kernel/printk/printk.c:1930 > vprintk_default+0x28/0x30 kernel/printk/printk.c:1958 > vprintk_func+0x7e/0x189 kernel/printk/printk_safe.c:398 > printk+0xba/0xed kernel/printk/printk.c:1991 __warn+0x9e/0x1d0 > kernel/panic.c:526 report_bug+0x263/0x2b0 lib/bug.c:186 > fixup_bug arch/x86/kernel/traps.c:178 [inline] > fixup_bug arch/x86/kernel/traps.c:173 [inline] > do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:271 > do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:290 > invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:973 > RIP: 0010:setup_new_dl_entity kernel/sched/deadline.c:628 [inline] > RIP: 0010:enqueue_dl_entity kernel/sched/deadline.c:1429 [inline] > RIP: 0010:enqueue_task_dl+0x2355/0x3dc0 kernel/sched/deadline.c:1500 > Code: 3c 02 00 0f 85 ba 05 00 00 49 8b b5 50 0a 00 00 e9 53 fa ff ff > e8 fb f2 64 00 48 8d 4d d8 e9 48 dd ff ff 0f 0b e9 92 f1 ff ff <0f> > 0b e9 18 f1 ff ff 4c 89 ef 4c 89 95 28 ff ff ff 4c 89 85 30 ff > RSP: 0018:ffff88809eebfaf8 EFLAGS: 00010002 > RAX: 0000000000000002 RBX: 1ffff11013dd7f6a RCX: dffffc0000000000 > RDX: 000000333cf09f75 RSI: 0000000000000004 RDI: ffff8880ae62d850 > RBP: ffff88809eebfbf8 R08: ffff88807fb0a538 R09: ffff88807fb0a2fc > R10: ffff88807fb0a580 R11: ffff8880ae62dc7b R12: ffff88807fb0a2c0 > R13: ffff8880ae62ce00 R14: ffff8880ae62ce00 R15: ffff88807fb0a58c > enqueue_task+0xb9/0x380 kernel/sched/core.c:730 > __sched_setscheduler+0xe32/0x1fe0 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+0x1af/0x2f0 kernel/sched/core.c:4549 > do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > RIP: 0033:0x44c829 > Code: e8 8c d8 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 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 eb c9 fb ff c3 66 2e 0f 1f 84 00 00 00 00 > RSP: 002b:00007f28685e8ce8 EFLAGS: 00000246 ORIG_RAX: 000000000000013a > RAX: ffffffffffffffda RBX: 00000000006e49f8 RCX: 000000000044c829 > RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000000 > RBP: 00000000006e49f0 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006e49fc > R13: 00007ffd1981c8af R14: 00007f28685e99c0 R15: 0000000000000001 > Shutting down cpus with NMI > Kernel Offset: disabled > Rebooting in 86400 seconds.. >