svn commit: r333480 - head/sys/kern

[Peter Holm]

On Fri, May 11, 2018 at 04:54:13AM +0000, Matt Macy wrote:
> Author: mmacy
> Date: Fri May 11 04:54:12 2018
> New Revision: 333480
> URL: https://svnweb.freebsd.org/changeset/base/333480
> 
> Log:
>   epoch(9): fix priority handling, make callback lists pcpu, and other fixes
>   
>   - Lend priority to preempted threads in epoch_wait to handle the case
>     in which we've had priority lent to us. Previously we borrowed the
>     priority of the lowest priority preempted thread. (pointed out by mjg@)
>   
>   - Don't attempt allocate memory per-domain on powerpc, we don't currently
>     handle empty sockets (as is the case on jhibbits Talos' board).
>   
>   - Handle deferred callbacks as pcpu lists and poll the lists periodically.
>     Currently the interval is 1/hz.
>   
>   - Drop the thread lock when adaptive spinning. Holding the lock starves
>     other threads and can even lead to lockups.
>   
>   - Keep a generation count pcpu so that we don't keep spining if a thread
>     has left and re-entered an epoch section.
>   
>   - Actually removed the callback from the callback list so that we don't
>     double free. Sigh ...
>   
>   Approved by:	sbruno@
> 
> Modified:
>   head/sys/kern/subr_epoch.c
> 
> Modified: head/sys/kern/subr_epoch.c
> ==============================================================================
> --- head/sys/kern/subr_epoch.c	Fri May 11 04:47:05 2018	(r333479)

Could this be yours?

cd0: Attempt to query device size failed: NOT READY, Medium not present - tray closed
WARNING: WITNESS option enabled, expect reduced performance.
WARNING: DIAGNOSTIC option enabled, expect reduced performance.
Trying to mount root from ufs:/dev/da0p2 [rw]...
Expensive timeout(9) function: 0xffffffff809f20d0(0xffffffff81af5140) 0.006730830 s
uhub1: 4 ports with 4 removable, self powered
kernel trap 12 with interrupts disabled


Fatal trap 12: page fault while in kernel mode
cpuid = 12; apic id = 20
fault virtual address   = 0x100
fault code              = supervisor read data, page not present
instruction pointer     = 0x20:0xffffffff80bb68db
stack pointer           = 0x0:0xfffffe00004e19b0
frame pointer           = 0x0:0xfffffe00004e19f0
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         = 0 (config_0)
[ thread pid 0 tid 100081 ]
Stopped at      epoch_call_task+0x7b:   movq    ll+0xdf(%rax),%rcx
db> show registers
cs                        0x20
ds                        0x3b  ll+0x1a
es                        0x3b  ll+0x1a
fs                        0x13
gs                        0x1b
ss                           0
rax                          0
rcx                      0x858  ll+0x837
rdx         0xffffffff812f6968
rbx                        0xc
rsp         0xfffffe00004e19b0
rbp         0xfffffe00004e19f0
rsi                       0x14
rdi                          0
r8          0xfffff800038f3000
r9          0xffffffff81ff1620  vmspace0+0x130
r10         0xfffff800038f3000
r11                       0x40  ll+0x1f
r12         0xfffffe00004e19b8
r13                        0xc
r14         0xfffff8001f0ed400
r15         0xfffff800038f3000
rip         0xffffffff80bb68db  epoch_call_task+0x7b
rflags                 0x10086
epoch_call_task+0x7b:   movq    ll+0xdf(%rax),%rcx
db> bt
Tracing pid 0 tid 100081 td 0xfffff800038f3000
epoch_call_task() at epoch_call_task+0x7b/frame 0xfffffe00004e19f0
gtaskqueue_run_locked() at gtaskqueue_run_locked+0x139/frame 0xfffffe00004e1a40
gtaskqueue_thread_loop() at gtaskqueue_thread_loop+0x88/frame 0xfffffe00004e1a70
fork_exit() at fork_exit+0x84/frame 0xfffffe00004e1ab0
fork_trampoline() at fork_trampoline+0xe/frame 0xfffffe00004e1ab0
--- trap 0, rip = 0, rsp = 0, rbp = 0 ---
db> x/s version
version:        FreeBSD 12.0-CURRENT #0 r333481: Fri May 11 09:08:40 CEST 2018\012    pho at t2.osted.lan:/usr/obj/usr/src/amd64.amd64/sys/PHO\012
db> 

- Peter