From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: <3rj27WgkbAPElrsdTeeXkTiibW.ZhhZeXnlXkVhgmXgm.Vhf@M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com> ARC-Seal: i=1; a=rsa-sha256; t=1522220462; cv=none; d=google.com; s=arc-20160816; b=jH3Rmt/gjv8QwEegxwvp3CcBbgoIYlZEwX4zMJzAUmH5q4VF7J8gPcVvlQhicLHRqb 64PcLfIgvRztE+NYefWoyE+Hu26HC/XztBFkGdKUsiHDdqn+7YyMx7cxR8nF9w0FbgTn ZETv+7pLaGypmkKGQj7mgrpW/ToH+RxGkoie6juJV8oc5nJkw1k8DMi502MnRYa6NzNB DWIGI903XD4BgCfJ0Hs9kq5p6ae/IpB2BkCqQdylAUkHHo9HIf2781Y0NgHZ6MN7KS30 wou5v6d3afdlEJtliSirBlpEsnNZdO2CZ8ljmZFdcQ6i/L4L4KF5sy0FPNpLP7fcO0WG JC+g== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=to:from:subject:message-id:date:mime-version :arc-authentication-results; bh=JnUvmEExLz0H8hZ0JQLotNhL3Ez5h4wuzX9NeHBPCEs=; b=byqD68MEUL50QL1txv4U1H9ZlAzHz8simo9OHueSCkgKVd5ac+YGAkt17MaVx/qWi2 CxxdwKk6gML66mfKEaZ1+uPKOevxChZykiiGqeSDtO/t3dMvPWJXPyHCcV3VdBAtjthr ckv/aoG/bSDvLfUgYHJWyh69HtZCOBtNiTK6VOPiS86rw+D28+CG6WeqDbQkF16J47y4 0Y3MSpMenhbMS/326JO+7icC+Ir5xxilFx1fI85OechLKnTeSFf2NweVAEGVkoGir9zd xQPeUAfnW0jj8IPHOtn3/kzLz1Zo/Xtj9NgR/leAOIuYsV5OBX48XjTBaAlBEfAvQZUz n66Q== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of 3rj27wgkbapelrsdteexktiibw.zhhzexnlxkvhgmxgm.vhf@m3kw2wvrgufz5godrsrytgd7.apphosting.bounces.google.com designates 209.85.220.69 as permitted sender) smtp.mailfrom=3rj27WgkbAPElrsdTeeXkTiibW.ZhhZeXnlXkVhgmXgm.Vhf@M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=appspotmail.com Authentication-Results: mx.google.com; spf=pass (google.com: domain of 3rj27wgkbapelrsdteexktiibw.zhhzexnlxkvhgmxgm.vhf@m3kw2wvrgufz5godrsrytgd7.apphosting.bounces.google.com designates 209.85.220.69 as permitted sender) smtp.mailfrom=3rj27WgkbAPElrsdTeeXkTiibW.ZhhZeXnlXkVhgmXgm.Vhf@M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=appspotmail.com X-Google-Smtp-Source: AIpwx4/R8GDNsdR7IfEVqhqiRVOGPvYNuTsxS9E4x0EBGjaLPUEeWGQwctODAF3iEthr2LMWf6XKq3QUDfUlQFRz9fLacAd3Fp8N MIME-Version: 1.0 Date: Wed, 28 Mar 2018 00:01:02 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <001a1140e920eb829905687391d6@google.com> Subject: INFO: rcu detected stall in __process_echoes From: syzbot To: akpm@linux-foundation.org, aryabinin@virtuozzo.com, dvyukov@google.com, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, tchibo@google.com, tglx@linutronix.de Content-Type: text/plain; charset="UTF-8"; format=flowed; delsp=yes X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1596163843273194959?= X-GMAIL-MSGID: =?utf-8?q?1596163843273194959?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: Hello, syzbot hit the following crash on upstream commit 3eb2ce825ea1ad89d20f7a3b5780df850e4be274 (Sun Mar 25 22:44:30 2018 +0000) Linux 4.16-rc7 syzbot dashboard link: https://syzkaller.appspot.com/bug?extid=108696293d7a21ab688f So far this crash happened 10 times on upstream. C reproducer: https://syzkaller.appspot.com/x/repro.c?id=4941573204738048 syzkaller reproducer: https://syzkaller.appspot.com/x/repro.syz?id=5314352743710720 Raw console output: https://syzkaller.appspot.com/x/log.txt?id=5561943247028224 Kernel config: https://syzkaller.appspot.com/x/.config?id=-8440362230543204781 compiler: gcc (GCC) 7.1.1 20170620 IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+108696293d7a21ab688f@syzkaller.appspotmail.com It will help syzbot understand when the bug is fixed. See footer for details. If you forward the report, please keep this part and the footer. INFO: rcu_sched self-detected stall on CPU 0-....: (124999 ticks this GP) idle=6aa/1/4611686018427387906 softirq=9528/9528 fqs=31245 (t=125000 jiffies g=4714 c=4713 q=8) NMI backtrace for cpu 0 CPU: 0 PID: 51 Comm: kworker/u4:2 Not tainted 4.16.0-rc7+ #3 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events_unbound flush_to_ldisc Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x24d lib/dump_stack.c:53 nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x123/0x180 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_single_cpu_backtrace include/linux/nmi.h:156 [inline] rcu_dump_cpu_stacks+0x186/0x1de kernel/rcu/tree.c:1375 print_cpu_stall kernel/rcu/tree.c:1524 [inline] check_cpu_stall.isra.61+0xbb8/0x15b0 kernel/rcu/tree.c:1592 __rcu_pending kernel/rcu/tree.c:3361 [inline] rcu_pending kernel/rcu/tree.c:3423 [inline] rcu_check_callbacks+0x238/0xd20 kernel/rcu/tree.c:2763 update_process_times+0x30/0x60 kernel/time/timer.c:1636 tick_sched_handle+0x85/0x160 kernel/time/tick-sched.c:162 tick_sched_timer+0x42/0x120 kernel/time/tick-sched.c:1194 __run_hrtimer kernel/time/hrtimer.c:1349 [inline] __hrtimer_run_queues+0x39c/0xec0 kernel/time/hrtimer.c:1411 hrtimer_interrupt+0x2a5/0x6f0 kernel/time/hrtimer.c:1469 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1025 [inline] smp_apic_timer_interrupt+0x14a/0x700 arch/x86/kernel/apic/apic.c:1050 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:857 RIP: 0010:__write_once_size include/linux/compiler.h:215 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x4b/0x50 kernel/kcov.c:109 RSP: 0018:ffff8801d96170a8 EFLAGS: 00000293 ORIG_RAX: ffffffffffffff12 RAX: ffff8801d960a5c0 RBX: ffffc90001fb8000 RCX: ffffffff82f38349 RDX: 0000000000000000 RSI: 1ffff1003b2c15e4 RDI: ffffc90001fb9963 RBP: ffff8801d96170a8 R08: 1ffff1003b2c2dbd R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 000000057efa5704 R13: dffffc0000000000 R14: 000000057efa5704 R15: 0000000000003321 echo_buf drivers/tty/n_tty.c:144 [inline] __process_echoes+0x5c9/0x770 drivers/tty/n_tty.c:732 flush_echoes drivers/tty/n_tty.c:799 [inline] __receive_buf drivers/tty/n_tty.c:1615 [inline] n_tty_receive_buf_common+0x1380/0x2520 drivers/tty/n_tty.c:1709 n_tty_receive_buf2+0x33/0x40 drivers/tty/n_tty.c:1744 tty_ldisc_receive_buf+0xa7/0x180 drivers/tty/tty_buffer.c:456 tty_port_default_receive_buf+0x106/0x160 drivers/tty/tty_port.c:38 receive_buf drivers/tty/tty_buffer.c:475 [inline] flush_to_ldisc+0x3c4/0x590 drivers/tty/tty_buffer.c:524 process_one_work+0xc47/0x1bb0 kernel/workqueue.c:2113 worker_thread+0x223/0x1990 kernel/workqueue.c:2247 kthread+0x33c/0x400 kernel/kthread.c:238 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:406 --- This bug is generated by a dumb bot. It may contain errors. See https://goo.gl/tpsmEJ for details. Direct all questions to syzkaller@googlegroups.com. syzbot will keep track of this bug report. If you forgot to add the Reported-by tag, once the fix for this bug is merged into any tree, please reply to this email with: #syz fix: exact-commit-title If you want to test a patch for this bug, please reply with: #syz test: git://repo/address.git branch and provide the patch inline or as an attachment. To mark this as a duplicate of another syzbot report, please reply with: #syz dup: exact-subject-of-another-report If it's a one-off invalid bug report, please reply with: #syz invalid Note: if the crash happens again, it will cause creation of a new bug report. Note: all commands must start from beginning of the line in the email body.