On Sat, Jan 19, 2019 at 12:32 PM syzbot <syzbot+1505c80c74256c6118a5@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > Hello, > > syzbot found the following crash on: > > HEAD commit: 2339e91d0e66 Merge tag 'media/v5.0-1' of git://git.kernel... > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=175f2638c00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=abc3dc9b7a900258 > dashboard link: https://syzkaller.appspot.com/bug?extid=1505c80c74256c6118a5 > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12c4dc28c00000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15df4108c00000 Looking at the reproducer it looks like something with scheduler as it involves perf_event_open and sched_setattr. So +Peter and Mingo. Is it the same root cause as the other stalls involving sched_setattr? > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+1505c80c74256c6118a5@xxxxxxxxxxxxxxxxxxxxxxxxx > > audit: type=1400 audit(1547895693.874:36): avc: denied { map } for > pid=8427 comm="syz-executor786" path="/root/syz-executor786610373" > dev="sda1" ino=1426 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 > tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1 > hrtimer: interrupt took 42996 ns > rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: > rcu: (detected by 0, t=10502 jiffies, g=6469, q=3) > rcu: All QSes seen, last rcu_preempt kthread activity 10502 > (4295051508-4295041006), jiffies_till_next_fqs=1, root ->qsmask 0x0 > syz-executor786 R running task 21544 8437 8433 0x00000000 > Call Trace: > <IRQ> > sched_show_task kernel/sched/core.c:5293 [inline] > sched_show_task.cold+0x273/0x2d5 kernel/sched/core.c:5268 > print_other_cpu_stall.cold+0x7f2/0x8bb kernel/rcu/tree.c:1301 > check_cpu_stall kernel/rcu/tree.c:1429 [inline] > rcu_pending kernel/rcu/tree.c:3018 [inline] > rcu_check_callbacks+0xf36/0x1380 kernel/rcu/tree.c:2521 > update_process_times+0x32/0x80 kernel/time/timer.c:1635 > tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:161 > tick_sched_timer+0x47/0x130 kernel/time/tick-sched.c:1271 > __run_hrtimer kernel/time/hrtimer.c:1389 [inline] > __hrtimer_run_queues+0x3a7/0x1050 kernel/time/hrtimer.c:1451 > hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1509 > local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1035 [inline] > smp_apic_timer_interrupt+0x18d/0x760 arch/x86/kernel/apic/apic.c:1060 > apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:807 > </IRQ> > RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:26 [inline] > RIP: 0010:check_kcov_mode kernel/kcov.c:67 [inline] > RIP: 0010:write_comp_data+0x9/0x70 kernel/kcov.c:122 > Code: 12 00 00 8b 80 dc 12 00 00 48 8b 11 48 83 c2 01 48 39 d0 76 07 48 89 > 34 d1 48 89 11 5d c3 0f 1f 00 65 4c 8b 04 25 40 ee 01 00 <65> 8b 05 80 ee > 7f 7e a9 00 01 1f 00 75 51 41 8b 80 d8 12 00 00 83 > RSP: 0018:ffff888080466f58 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 > RAX: 000000000000226d RBX: ffff888080467140 RCX: ffffffff87f08bdf > RDX: 0000000000000002 RSI: 0000000000000002 RDI: 0000000000000007 > RBP: ffff888080466f60 R08: ffff888096338480 R09: ffffed1015cc5b90 > R10: ffffed1015cc5b8f R11: ffff8880ae62dc7b R12: 1ffff1101008cdf0 > R13: ffff888092b64102 R14: ffff888092b64102 R15: ffff888080467158 > xa_is_node include/linux/xarray.h:946 [inline] > xas_start+0x1cf/0x720 lib/xarray.c:183 > xas_load+0x21/0x160 lib/xarray.c:227 > find_get_entry+0x350/0x10a0 mm/filemap.c:1476 > pagecache_get_page+0xe6/0x1020 mm/filemap.c:1579 > find_get_page include/linux/pagemap.h:272 [inline] > generic_file_buffered_read mm/filemap.c:2076 [inline] > generic_file_read_iter+0x7b2/0x2d40 mm/filemap.c:2350 > ext4_file_read_iter+0x180/0x3c0 fs/ext4/file.c:77 > call_read_iter include/linux/fs.h:1856 [inline] > generic_file_splice_read+0x5c4/0xa90 fs/splice.c:308 > do_splice_to+0x12a/0x190 fs/splice.c:880 > splice_direct_to_actor+0x31b/0x9d0 fs/splice.c:957 > do_splice_direct+0x2c7/0x420 fs/splice.c:1066 > do_sendfile+0x61a/0xe60 fs/read_write.c:1436 > __do_sys_sendfile64 fs/read_write.c:1491 [inline] > __se_sys_sendfile64 fs/read_write.c:1483 [inline] > __x64_sys_sendfile64+0x15a/0x240 fs/read_write.c:1483 > do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > RIP: 0033:0x446a19 > Code: e8 dc e6 ff ff 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 4b 07 fc ff c3 66 2e 0f 1f 84 00 00 00 00 > RSP: 002b:00007f53e33cfda8 EFLAGS: 00000297 ORIG_RAX: 0000000000000028 > RAX: ffffffffffffffda RBX: 00000000006dcc28 RCX: 0000000000446a19 > RDX: 0000000020000380 RSI: 0000000000000003 RDI: 0000000000000003 > RBP: 00000000006dcc20 R08: 0000000000000000 R09: 0000000000000000 > R10: 00008080fffffffe R11: 0000000000000297 R12: 00000000006dcc2c > R13: 00008080fffffffe R14: 00007f53e33d09c0 R15: 00000000006dcd2c > rcu: rcu_preempt kthread starved for 10502 jiffies! g6469 f0x2 > RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 > rcu: RCU grace-period kthread stack dump: > rcu_preempt R running task 26200 10 2 0x80000000 > Call Trace: > context_switch kernel/sched/core.c:2831 [inline] > __schedule+0x897/0x1e60 kernel/sched/core.c:3472 > schedule+0xfe/0x350 kernel/sched/core.c:3516 > schedule_timeout+0x14a/0x250 kernel/time/timer.c:1803 > rcu_gp_fqs_loop+0x6ba/0x970 kernel/rcu/tree.c:1948 > rcu_gp_kthread+0x2bb/0xc10 kernel/rcu/tree.c:2105 > kthread+0x357/0x430 kernel/kthread.c:246 > ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352 > sched: RT throttling activated > > > --- > 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@xxxxxxxxxxxxxxxx. > > 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 > > -- > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group. > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@xxxxxxxxxxxxxxxx. > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/00000000000010b2fc057fcdfaba%40google.com. > For more options, visit https://groups.google.com/d/optout.
