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charset="UTF-8"; format=flowed; delsp=yes Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Hello, syzbot found the following crash on: HEAD commit: bb2aee77 Add linux-next specific files for 20190926 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=13385ca3600000 kernel config: https://syzkaller.appspot.com/x/.config?x=e60af4ac5a01e964 dashboard link: https://syzkaller.appspot.com/bug?extid=24c12fa8d218ed26011a compiler: gcc (GCC) 9.0.0 20181231 (experimental) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12abc2a3600000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11712c05600000 The bug was bisected to: commit e9e006f5fcf2bab59149cb38a48a4817c1b538b4 Author: Mike Christie Date: Sun Aug 4 19:10:06 2019 +0000 nbd: fix max number of supported devs bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1226f3c5600000 final crash: https://syzkaller.appspot.com/x/report.txt?x=1126f3c5600000 console output: https://syzkaller.appspot.com/x/log.txt?x=1626f3c5600000 IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+24c12fa8d218ed26011a@syzkaller.appspotmail.com Fixes: e9e006f5fcf2 ("nbd: fix max number of supported devs") INFO: task syz-executor390:8778 can't die for more than 143 seconds. syz-executor390 D27432 8778 8777 0x00004004 Call Trace: context_switch kernel/sched/core.c:3384 [inline] __schedule+0x828/0x1c20 kernel/sched/core.c:4065 schedule+0xd9/0x260 kernel/sched/core.c:4132 schedule_timeout+0x717/0xc50 kernel/time/timer.c:1871 do_wait_for_common kernel/sched/completion.c:83 [inline] __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common kernel/sched/completion.c:115 [inline] wait_for_completion+0x29c/0x440 kernel/sched/completion.c:136 flush_workqueue+0x40f/0x14c0 kernel/workqueue.c:2826 nbd_start_device_ioctl drivers/block/nbd.c:1272 [inline] __nbd_ioctl drivers/block/nbd.c:1347 [inline] nbd_ioctl+0xb2e/0xc44 drivers/block/nbd.c:1387 __blkdev_driver_ioctl block/ioctl.c:304 [inline] blkdev_ioctl+0xedb/0x1c20 block/ioctl.c:606 block_ioctl+0xee/0x130 fs/block_dev.c:1954 vfs_ioctl fs/ioctl.c:47 [inline] file_ioctl fs/ioctl.c:539 [inline] do_vfs_ioctl+0xdb6/0x13e0 fs/ioctl.c:726 ksys_ioctl+0xab/0xd0 fs/ioctl.c:743 __do_sys_ioctl fs/ioctl.c:750 [inline] __se_sys_ioctl fs/ioctl.c:748 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:748 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4452d9 Code: Bad RIP value. RSP: 002b:00007ffde928d288 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004452d9 RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000004 RBP: 0000000000000000 R08: 00000000004025b0 R09: 00000000004025b0 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000402520 R13: 00000000004025b0 R14: 0000000000000000 R15: 0000000000000000 INFO: task syz-executor390:8778 blocked for more than 143 seconds. Not tainted 5.3.0-next-20190926 #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor390 D27432 8778 8777 0x00004004 Call Trace: context_switch kernel/sched/core.c:3384 [inline] __schedule+0x828/0x1c20 kernel/sched/core.c:4065 schedule+0xd9/0x260 kernel/sched/core.c:4132 schedule_timeout+0x717/0xc50 kernel/time/timer.c:1871 do_wait_for_common kernel/sched/completion.c:83 [inline] __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common kernel/sched/completion.c:115 [inline] wait_for_completion+0x29c/0x440 kernel/sched/completion.c:136 flush_workqueue+0x40f/0x14c0 kernel/workqueue.c:2826 nbd_start_device_ioctl drivers/block/nbd.c:1272 [inline] __nbd_ioctl drivers/block/nbd.c:1347 [inline] nbd_ioctl+0xb2e/0xc44 drivers/block/nbd.c:1387 __blkdev_driver_ioctl block/ioctl.c:304 [inline] blkdev_ioctl+0xedb/0x1c20 block/ioctl.c:606 block_ioctl+0xee/0x130 fs/block_dev.c:1954 vfs_ioctl fs/ioctl.c:47 [inline] file_ioctl fs/ioctl.c:539 [inline] do_vfs_ioctl+0xdb6/0x13e0 fs/ioctl.c:726 ksys_ioctl+0xab/0xd0 fs/ioctl.c:743 __do_sys_ioctl fs/ioctl.c:750 [inline] __se_sys_ioctl fs/ioctl.c:748 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:748 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4452d9 Code: Bad RIP value. RSP: 002b:00007ffde928d288 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004452d9 RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000004 RBP: 0000000000000000 R08: 00000000004025b0 R09: 00000000004025b0 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000402520 R13: 00000000004025b0 R14: 0000000000000000 R15: 0000000000000000 Showing all locks held in the system: 1 lock held by khungtaskd/1066: #0: ffffffff88faad80 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x27e kernel/locking/lockdep.c:5337 2 locks held by kworker/u5:0/1525: #0: ffff8880923d0d28 ((wq_completion)knbd0-recv){+.+.}, at: __write_once_size include/linux/compiler.h:226 [inline] #0: ffff8880923d0d28 ((wq_completion)knbd0-recv){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff8880923d0d28 ((wq_completion)knbd0-recv){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:855 [inline] #0: ffff8880923d0d28 ((wq_completion)knbd0-recv){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:40 [inline] #0: ffff8880923d0d28 ((wq_completion)knbd0-recv){+.+.}, at: set_work_data kernel/workqueue.c:620 [inline] #0: ffff8880923d0d28 ((wq_completion)knbd0-recv){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:647 [inline] #0: ffff8880923d0d28 ((wq_completion)knbd0-recv){+.+.}, at: process_one_work+0x88b/0x1740 kernel/workqueue.c:2240 #1: ffff8880a63b7dc0 ((work_completion)(&args->work)){+.+.}, at: process_one_work+0x8c1/0x1740 kernel/workqueue.c:2244 1 lock held by rsyslogd/8659: 2 locks held by getty/8749: #0: ffff888098c08090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f112e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/8750: #0: ffff88808f10b090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f2d2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/8751: #0: ffff88809a6be090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f192e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/8752: #0: ffff8880a48af090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f352e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/8753: #0: ffff88808c599090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f212e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/8754: #0: ffff88808f1a8090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f392e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/8755: #0: ffff88809ab33090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f012e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1066 Comm: khungtaskd Not tainted 5.3.0-next-20190926 #0 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 nmi_cpu_backtrace.cold+0x70/0xb2 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x23b/0x28b lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:269 [inline] watchdog+0xc99/0x1360 kernel/hung_task.c:353 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:60 --- 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#status for how to communicate with syzbot. For information about bisection process see: https://goo.gl/tpsmEJ#bisection syzbot can test patches for this bug, for details see: https://goo.gl/tpsmEJ#testing-patches