syzbot


INFO: task hung in tty_poll

Status: public: reported C repro on 2019/05/01 07:35
Reported-by: syzbot+19d5127048d3d24a1aa9@syzkaller.appspotmail.com
First crash: 2031d, last: 1834d

Sample crash report:
updating oom_score_adj for 7633 (syz-executor273) from 1000 to 1000 because it shares mm with 7635 (syz-executor273). Report if this is unexpected.
updating oom_score_adj for 7637 (syz-executor273) from 1000 to 1000 because it shares mm with 7640 (syz-executor273). Report if this is unexpected.
INFO: task syz-executor273:3839 blocked for more than 140 seconds.
      Not tainted 4.9.141+ #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor273 D29544  3839   2490 0x00000000
 ffff8801d7d6df00 0000000000000000 ffff8801d8003700 ffff8801da6b2f80
 ffff8801db721018 ffff8801d7c87a00 ffffffff828075c2 ffff8801d7c87a10
 ffffffff83cc2f20 ffff8801d99987ff 00000000000061b9 ffff8801db7218f0
Call Trace:
 [<ffffffff82808aef>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff828142d5>] schedule_timeout+0x735/0xe20 kernel/time/timer.c:1771
 [<ffffffff81d4312c>] down_read_failed drivers/tty/tty_ldsem.c:241 [inline]
 [<ffffffff81d4312c>] __ldsem_down_read_nested+0x33c/0x610 drivers/tty/tty_ldsem.c:332
 [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 [<ffffffff81d3ca85>] tty_ldisc_ref_wait+0x25/0x80 drivers/tty/tty_ldisc.c:275
 [<ffffffff81d22005>] tty_poll+0xc5/0x190 drivers/tty/tty_io.c:2232
 [<ffffffff815efcff>] ep_item_poll fs/eventpoll.c:811 [inline]
 [<ffffffff815efcff>] ep_insert fs/eventpoll.c:1347 [inline]
 [<ffffffff815efcff>] SYSC_epoll_ctl fs/eventpoll.c:1975 [inline]
 [<ffffffff815efcff>] SyS_epoll_ctl+0x119f/0x25d0 fs/eventpoll.c:1861
 [<ffffffff810056ef>] do_syscall_64+0x19f/0x550 arch/x86/entry/common.c:285
 [<ffffffff82817893>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/24:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8131c0cc>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8131c0cc>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff813fe63f>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/2029:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff81d37362>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
2 locks held by syz-executor273/3838:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff81d37362>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
2 locks held by syz-executor273/3839:
 #0:  (&ep->mtx){+.+.+.}, at: [<ffffffff815ef3d9>] SYSC_epoll_ctl fs/eventpoll.c:1939 [inline]
 #0:  (&ep->mtx){+.+.+.}, at: [<ffffffff815ef3d9>] SyS_epoll_ctl+0x879/0x25d0 fs/eventpoll.c:1861
 #1:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor273/4496:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff81d37362>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
2 locks held by syz-executor273/4497:
 #0:  (&ep->mtx){+.+.+.}, at: [<ffffffff815ef3d9>] SYSC_epoll_ctl fs/eventpoll.c:1939 [inline]
 #0:  (&ep->mtx){+.+.+.}, at: [<ffffffff815ef3d9>] SyS_epoll_ctl+0x879/0x25d0 fs/eventpoll.c:1861
 #1:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor273/4500:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff81d37362>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
2 locks held by syz-executor273/4501:
 #0:  (&ep->mtx){+.+.+.}, at: [<ffffffff815ef3d9>] SYSC_epoll_ctl fs/eventpoll.c:1939 [inline]
 #0:  (&ep->mtx){+.+.+.}, at: [<ffffffff815ef3d9>] SyS_epoll_ctl+0x879/0x25d0 fs/eventpoll.c:1861
 #1:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor273/4618:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff81d37362>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
2 locks held by syz-executor273/4620:
 #0:  (&ep->mtx){+.+.+.}, at: [<ffffffff815ef3d9>] SYSC_epoll_ctl fs/eventpoll.c:1939 [inline]
 #0:  (&ep->mtx){+.+.+.}, at: [<ffffffff815ef3d9>] SyS_epoll_ctl+0x879/0x25d0 fs/eventpoll.c:1861
 #1:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor273/4638:
 #0:  (&ep->mtx){+.+.+.}, at: [<ffffffff815ef3d9>] SYSC_epoll_ctl fs/eventpoll.c:1939 [inline]
 #0:  (&ep->mtx){+.+.+.}, at: [<ffffffff815ef3d9>] SyS_epoll_ctl+0x879/0x25d0 fs/eventpoll.c:1861
 #1:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor273/4639:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff81d37362>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
2 locks held by syz-executor273/4834:
 #0:  (&ep->mtx){+.+.+.}, at: [<ffffffff815ef3d9>] SYSC_epoll_ctl fs/eventpoll.c:1939 [inline]
 #0:  (&ep->mtx){+.+.+.}, at: [<ffffffff815ef3d9>] SyS_epoll_ctl+0x879/0x25d0 fs/eventpoll.c:1861
 #1:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor273/4835:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff81d37362>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
2 locks held by syz-executor273/5502:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff81d37362>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
2 locks held by syz-executor273/5503:
 #0:  (&ep->mtx){+.+.+.}, at: [<ffffffff815ef3d9>] SYSC_epoll_ctl fs/eventpoll.c:1939 [inline]
 #0:  (&ep->mtx){+.+.+.}, at: [<ffffffff815ef3d9>] SyS_epoll_ctl+0x879/0x25d0 fs/eventpoll.c:1861
 #1:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor273/5506:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff81d37362>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
2 locks held by syz-executor273/5507:
 #0:  (&ep->mtx){+.+.+.}, at: [<ffffffff815ef3d9>] SYSC_epoll_ctl fs/eventpoll.c:1939 [inline]
 #0:  (&ep->mtx){+.+.+.}, at: [<ffffffff815ef3d9>] SyS_epoll_ctl+0x879/0x25d0 fs/eventpoll.c:1861
 #1:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor273/7438:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff81d37362>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
2 locks held by syz-executor273/7439:
 #0:  (&ep->mtx){+.+.+.}, at: [<ffffffff815ef3d9>] SYSC_epoll_ctl fs/eventpoll.c:1939 [inline]
 #0:  (&ep->mtx){+.+.+.}, at: [<ffffffff815ef3d9>] SyS_epoll_ctl+0x879/0x25d0 fs/eventpoll.c:1861
 #1:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor273/7653:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff81d37362>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
2 locks held by syz-executor273/7654:
 #0:  (&ep->mtx){+.+.+.}, at: [<ffffffff815ef3d9>] SYSC_epoll_ctl fs/eventpoll.c:1939 [inline]
 #0:  (&ep->mtx){+.+.+.}, at: [<ffffffff815ef3d9>] SyS_epoll_ctl+0x879/0x25d0 fs/eventpoll.c:1861
 #1:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor273/7655:
 #0:  (&tty->legacy_mutex){+.+.+.}, at: [<ffffffff81d4222a>] tty_lock+0x6a/0xd0 drivers/tty/tty_mutex.c:18
 #1:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815992>] ldsem_down_write+0x32/0x37 drivers/tty/tty_ldsem.c:393

=============================================

NMI backtrace for cpu 0
CPU: 0 PID: 24 Comm: khungtaskd Not tainted 4.9.141+ #1
 ffff8801d9907d08 ffffffff81b42e79 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810983b0 ffff8801d9907d40
 ffffffff81b4df89 0000000000000000 0000000000000000 0000000000000002
Call Trace:
 [<ffffffff81b42e79>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81b42e79>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81b4df89>] nmi_cpu_backtrace.cold.0+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81b4df1c>] nmi_trigger_cpumask_backtrace+0x12c/0x151 lib/nmi_backtrace.c:60
 [<ffffffff810984b4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff8131c65d>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff8131c65d>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff8131c65d>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff8131c65d>] watchdog+0x6ad/0xa20 kernel/hung_task.c:239
 [<ffffffff81142c3d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff82817a5c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at pc 0xffffffff82816496

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2019/05/01 06:44 https://android.googlesource.com/kernel/common android-4.9 8fe428403e30 618456b4 .config console log report syz C ci-android-49-kasan-gce
2019/05/01 06:34 https://android.googlesource.com/kernel/common android-4.9 8fe428403e30 618456b4 .config console log report syz ci-android-49-kasan-gce-386
2019/11/12 03:32 https://android.googlesource.com/kernel/common android-4.9 8fe428403e30 048f2d49 .config console log report ci-android-49-kasan-gce
2019/11/13 23:50 https://android.googlesource.com/kernel/common android-4.9 8fe428403e30 048f2d49 .config console log report ci-android-49-kasan-gce-386
* Struck through repros no longer work on HEAD.