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[2001:44b8:1113:6700:5cb3:ebc3:7dc6:a17b]) by smtp.gmail.com with ESMTPSA id x21sm4660362pfn.164.2020.01.08.14.07.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 08 Jan 2020 14:07:48 -0800 (PST) From: Daniel Axtens To: Dmitry Vyukov , syzbot Cc: Andrew Morton , Christian Brauner , Kees Cook , LKML , Andy Lutomirski , Ingo Molnar , Peter Zijlstra , syzkaller-bugs , Thomas Gleixner , Will Drewry , Tetsuo Handa Subject: Re: INFO: rcu detected stall in sys_poll (2) In-Reply-To: References: <000000000000322ad2059b9aa992@google.com> Date: Thu, 09 Jan 2020 09:07:44 +1100 Message-ID: <87eew9ob4f.fsf@dja-thinkpad.axtens.net> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dmitry Vyukov writes: > On Wed, Jan 8, 2020 at 7:04 AM syzbot > wrote: >> >> Hello, >> >> syzbot found the following crash on: >> >> HEAD commit: ae608821 Merge tag 'trace-v5.5-rc5' of git://git.kernel.or.. >> git tree: upstream >> console output: https://syzkaller.appspot.com/x/log.txt?x=157edeb9e00000 >> kernel config: https://syzkaller.appspot.com/x/.config?x=db5ff86cbb23b415 >> dashboard link: https://syzkaller.appspot.com/bug?extid=c3ed57cd8f699826dd95 >> compiler: clang version 9.0.0 (/home/glider/llvm/clang >> 80fee25776c2fb61e74c1ecb1a523375c2500b69) >> >> Unfortunately, I don't have any reproducer for this crash yet. >> >> IMPORTANT: if you fix the bug, please add the following tag to the commit: >> Reported-by: syzbot+c3ed57cd8f699826dd95@syzkaller.appspotmail.com > > This is: > > #syz dup: INFO: rcu detected stall in sys_kill > > For details see: > https://groups.google.com/g/syzkaller-bugs/c/Vv3ARjLvagc/m/nZAubeo9AQAJ > https://syzkaller.appspot.com/bug?extid=de8d933e7d153aa0c1bb > > I temporarily re-enabled smack instance and it produces another 50 > stalls all over the kernel. So smack + KASAN + VMAP stack combination > is sitll problematic. > I'm just back this week, so I'll try and have another look in the next couple of days, but I've been really struggling to get anywhere. Regards, Daniel > >> rcu: INFO: rcu_preempt self-detected stall on CPU >> rcu: 0-...!: (1 GPs behind) idle=5da/1/0x4000000000000002 >> softirq=13907/13908 fqs=38 >> (t=10501 jiffies g=6889 q=136) >> rcu: rcu_preempt kthread starved for 10426 jiffies! g6889 f0x0 >> RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 >> rcu: RCU grace-period kthread stack dump: >> rcu_preempt R running task 29032 10 2 0x80004000 >> Call Trace: >> context_switch kernel/sched/core.c:3385 [inline] >> __schedule+0x9a0/0xcc0 kernel/sched/core.c:4081 >> schedule+0x181/0x210 kernel/sched/core.c:4155 >> schedule_timeout+0x14f/0x240 kernel/time/timer.c:1895 >> rcu_gp_fqs_loop kernel/rcu/tree.c:1661 [inline] >> rcu_gp_kthread+0xed8/0x1770 kernel/rcu/tree.c:1821 >> kthread+0x332/0x350 kernel/kthread.c:255 >> ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 >> NMI backtrace for cpu 0 >> CPU: 0 PID: 8477 Comm: udevd Not tainted 5.5.0-rc5-syzkaller #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+0x1fb/0x318 lib/dump_stack.c:118 >> nmi_cpu_backtrace+0xaf/0x1a0 lib/nmi_backtrace.c:101 >> nmi_trigger_cpumask_backtrace+0x174/0x290 lib/nmi_backtrace.c:62 >> arch_trigger_cpumask_backtrace+0x10/0x20 arch/x86/kernel/apic/hw_nmi.c:38 >> trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] >> rcu_dump_cpu_stacks+0x15a/0x220 kernel/rcu/tree_stall.h:254 >> print_cpu_stall kernel/rcu/tree_stall.h:455 [inline] >> check_cpu_stall kernel/rcu/tree_stall.h:529 [inline] >> rcu_pending kernel/rcu/tree.c:2827 [inline] >> rcu_sched_clock_irq+0xe25/0x1ad0 kernel/rcu/tree.c:2271 >> update_process_times+0x12d/0x180 kernel/time/timer.c:1726 >> tick_sched_handle kernel/time/tick-sched.c:167 [inline] >> tick_sched_timer+0x263/0x420 kernel/time/tick-sched.c:1310 >> __run_hrtimer kernel/time/hrtimer.c:1517 [inline] >> __hrtimer_run_queues+0x403/0x840 kernel/time/hrtimer.c:1579 >> hrtimer_interrupt+0x38c/0xda0 kernel/time/hrtimer.c:1641 >> local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline] >> smp_apic_timer_interrupt+0x109/0x280 arch/x86/kernel/apic/apic.c:1135 >> apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 >> >> RIP: 0010:free_thread_stack+0x151/0x590 kernel/fork.c:280 >> Code: 31 f6 e8 02 8d 6f 00 43 80 3c 2e 00 74 08 4c 89 e7 e8 73 94 6a 00 49 >> 8b 1c 24 48 83 c3 08 48 89 d8 48 c1 e8 03 42 80 3c 28 00 <74> 08 48 89 df >> e8 55 94 6a 00 48 8b 3b be fc ff ff ff e8 28 04 00 >> RSP: 0018:ffffc90001e57760 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 >> RAX: 1ffff11013e8ed61 RBX: ffff88809f476b08 RCX: 0000000000000000 >> RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffea0002a59a40 >> RBP: ffffc90001e57798 R08: 000000000003a728 R09: ffffed10125b3711 >> R10: ffffed10125b3711 R11: 0000000000000000 R12: ffff88809f476a20 >> R13: dffffc0000000000 R14: 1ffff11013e8ed44 R15: ffff888092d9b878 >> release_task_stack kernel/fork.c:440 [inline] >> put_task_stack+0xa3/0x130 kernel/fork.c:451 >> finish_task_switch+0x3f1/0x550 kernel/sched/core.c:3256 >> context_switch kernel/sched/core.c:3388 [inline] >> __schedule+0x9a8/0xcc0 kernel/sched/core.c:4081 >> schedule+0x181/0x210 kernel/sched/core.c:4155 >> schedule_hrtimeout_range_clock+0x3c7/0x510 kernel/time/hrtimer.c:2130 >> schedule_hrtimeout_range+0x2a/0x40 kernel/time/hrtimer.c:2175 >> poll_schedule_timeout+0x11c/0x1c0 fs/select.c:243 >> do_poll fs/select.c:951 [inline] >> do_sys_poll+0x83f/0x1250 fs/select.c:1001 >> __do_sys_poll fs/select.c:1059 [inline] >> __se_sys_poll+0x1b0/0x360 fs/select.c:1047 >> __x64_sys_poll+0x7b/0x90 fs/select.c:1047 >> do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 >> entry_SYSCALL_64_after_hwframe+0x49/0xbe >> RIP: 0033:0x7fe82049b678 >> Code: 11 48 83 c8 ff eb ea 90 90 90 90 90 90 90 90 90 90 90 48 83 ec 28 8b >> 05 82 8f 2b 00 85 c0 75 17 48 63 d2 b8 07 00 00 00 0f 05 <48> 3d 00 f0 ff >> ff 77 51 48 83 c4 28 c3 89 54 24 08 48 89 74 24 10 >> RSP: 002b:00007fffd9dcc090 EFLAGS: 00000246 ORIG_RAX: 0000000000000007 >> RAX: ffffffffffffffda RBX: 20c49ba5e353f7cf RCX: 00007fe82049b678 >> RDX: 000000000000ee2a RSI: 0000000000000001 RDI: 00007fffd9dcc150 >> RBP: 0000000000000000 R08: 00007fffd9dcc0a0 R09: 00007fffd9de50b8 >> R10: 0000000000000000 R11: 0000000000000246 R12: 000000000150dc00 >> R13: 000000000000214d R14: 00007fffd9dcc124 R15: 0000000001509250 >> >> >> --- >> 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. >> >> -- >> 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@googlegroups.com. >> To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/000000000000322ad2059b9aa992%40google.com.