Re: r286256 (changes in both schedulers) leads to almost-instant reboot on my system.

On Sun, Oct 25, 2015 at 10:44:06PM +0300, Lev Serebryakov wrote:
> Hello freebsd-current,
> 
>    I've tracked down my reboot on r289874 to r286256. My system crashes
>  after several  seconds of running with several post-286256 revisions
>  (r289874 is tested  most by me). But if I revert r286256 (and only this
>  one), r289874 works  solid-stable with both ULE and 4BSD. It is amd64
>  system.
td_oncpu and td_lastcpu are not used for anything in scheduler,
td_lastcpu usage is only advisory.

At least, show the source line for the sched_add+0x116.
But you probably already know that a full backtrace from kgdb,
with locals, and print-out of the current thread structure would
be useful to see what is going on.

> 
>   Typical panic logs look like this:
> 
> ======================================================================
> gif0: link state changed to UP
> kernel trap 9 with interrupts disabled
> 
> 
> Fatal trap 9: general protection fault while in kernel mode
> cpuid = 0; apic id = 00
> instruction pointer     = 0x20:0xffffffff8046e3c6
> stack pointer           = 0x28:0xfffffe011bd59890
> frame pointer           = 0x28:0xfffffe011bd59980
> code segment            = base 0x0, limit 0xfffff, type 0x1b
>                         = DPL 0, pres 1, long 1, def32 0, gran 1
> processor eflags        = resume, IOPL = 0
> current process         = 11 (swi4: clock (0))
> trap number             = 9
> panic: general protection fault
> cpuid = 0
> KDB: stack backtrace:
> db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe011bd59530
> vpanic() at vpanic+0x182/frame 0xfffffe011bd595b0
> panic() at panic+0x43/frame 0xfffffe011bd59610
> trap_fatal() at trap_fatal+0x351/frame 0xfffffe011bd59670
> trap() at trap+0x6d8/frame 0xfffffe011bd597d0
> calltrap() at calltrap+0x8/frame 0xfffffe011bd597d0
> --- trap 0x9, rip = 0xffffffff8046e3c6, rsp = 0xfffffe011bd598a0, rbp = 0xfffffe011bd59980 ---
> sched_add() at sched_add+0x116/frame 0xfffffe011bd59980
> intr_event_schedule_thread() at intr_event_schedule_thread+0xae/frame 0xfffffe011bd599b0
> intr_event_handle() at intr_event_handle+0xe2/frame 0xfffffe011bd59a00
> intr_execute_handlers() at intr_execute_handlers+0x48/frame 0xfffffe011bd59a30
> lapic_handle_intr() at lapic_handle_intr+0x3f/frame 0xfffffe011bd59a50
> Xapic_isr1() at Xapic_isr1+0xb7/frame 0xfffffe011bd59a50
> --- interrupt, rip = 0xffffffff8063e1f2, rsp = 0xfffffe011bd59b20, rbp = 0xfffffe011bd59b20 ---
> spinlock_exit() at spinlock_exit+0x32/frame 0xfffffe011bd59b20
> intr_event_execute_handlers() at intr_event_execute_handlers+0xae/frame 0xfffffe011bd59b60
> ithread_loop() at ithread_loop+0xa6/frame 0xfffffe011bd59bb0
> fork_exit() at fork_exit+0x75/frame 0xfffffe011bd59bf0
> fork_trampoline() at fork_trampoline+0xe/frame 0xfffffe011bd59bf0
> --- trap 0, rip = 0, rsp = 0, rbp = 0 ---
> Uptime: 16s
> ======================================================================
> wlan0: AP-ENABLED
> kernel trap 9 with interrupts disabled
> 
> 
> Fatal trap 9: general protection fault while in kernel mode
> cpuid = 0; apic id = 00
> instruction pointer     = 0x20:0xffffffff805190b6
> stack pointer           = 0x28:0xfffffe012260e7d0
> frame pointer           = 0x28:0xfffffe012260e8c0
> code segment            = base 0x0, limit 0xfffff, type 0x1b
>                         = DPL 0, pres 1, long 1, def32 0, gran 1
> processor eflags        = resume, IOPL = 0
> current process         = 16 (syncer)
> trap number             = 9
> panic: general protection fault
> cpuid = 0
> KDB: stack backtrace:
> db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe012260e470
> vpanic() at vpanic+0x182/frame 0xfffffe012260e4f0
> panic() at panic+0x43/frame 0xfffffe012260e550
> trap_fatal() at trap_fatal+0x351/frame 0xfffffe012260e5b0
> trap() at trap+0x6d8/frame 0xfffffe012260e710
> calltrap() at calltrap+0x8/frame 0xfffffe012260e710
> --- trap 0x9, rip = 0xffffffff805190b6, rsp = 0xfffffe012260e7e0, rbp = 0xfffffe012260e8c0 ---
> sched_add() at sched_add+0x116/frame 0xfffffe012260e8c0
> intr_event_schedule_thread() at intr_event_schedule_thread+0xae/frame 0xfffffe012260e8f0
> intr_event_handle() at intr_event_handle+0xe2/frame 0xfffffe012260e940
> intr_execute_handlers() at intr_execute_handlers+0x48/frame 0xfffffe012260e970
> lapic_handle_intr() at lapic_handle_intr+0x3f/frame 0xfffffe012260e990
> Xapic_isr1() at Xapic_isr1+0xb7/frame 0xfffffe012260e990
> --- interrupt, rip = 0xffffffff8071eaad, rsp = 0xfffffe012260ea60, rbp = 0xfffffe012260ea70 ---
> spinlock_exit() at spinlock_exit+0x2d/frame 0xfffffe012260ea70
> sleepq_timedwait() at sleepq_timedwait+0xd3/frame 0xfffffe012260eaa0
> _cv_timedwait_sbt() at _cv_timedwait_sbt+0x1a0/frame 0xfffffe012260eb10
> sched_sync() at sched_sync+0x6b6/frame 0xfffffe012260ebb0
> fork_exit() at fork_exit+0x75/frame 0xfffffe012260ebf0
> fork_trampoline() at fork_trampoline+0xe/frame 0xfffffe012260ebf0
> --- trap 0, rip = 0, rsp = 0, rbp = 0 ---
> Uptime: 14s
> ======================================================================
> 
> 
> -- 
> Best regards,
>  Lev                          mailto:lev_at_FreeBSD.org