kern/54009: "l->l_pcu_cpu[id] == NULL" panic on aarch64

[alnsn%yandex.ru@localhost]

>Number:         54009
>Category:       kern
>Synopsis:       "l->l_pcu_cpu[id] == NULL" panic on aarch64
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Feb 23 19:50:00 +0000 2019
>Originator:     Alexander Nasonov
>Release:        NetBSD 8.99.34 aarch64
>Organization:
XMM SWAP LTD
>Environment:
NetBSD nebula 8.99.34 NetBSD 8.99.34 (GENERIC64) #0: Sat Feb 16 15:17:35 GMT 2019  alnsn@nebeda:/home/alnsn/netbsd-current/sljit/src/sys/arch/evbarm/compile/obj/GENERIC64 evbarm

>Description:
My Scaleway aarch64 cloud server running two tor relays crashes randomly.
Some times it takes several days (or even a couple of weeks) before it
crashes. Other times, it crashes several times a day.

Stack traces isn't always available because Scaleway console doesn't always
connect properly to a crashed VM but I managed to get two stack traces:

panic: kernel diagnostic assertion "l->l_pcu_cpu[id] == NULL", file /home/alnsn/netbsd-current/sljit/src/sys/kern/subr_pcu.c, line 339
cpu9: Begin traceback...http://dmesgd.nycbug.org/index.cgi?do=view&id=4787
trace fp ffffffc1252bfcc0                                                                                                          
fp ffffffc1252bfce0 vpanic() at ffffffc00045fa08 netbsd:vpanic+0x198
fp ffffffc1252bfdb4 kern_assert() at ffffffc00058f6a4 netbsd:kern_assert+0x5c
fp ffffffc1252bfdd0 pcu_load() at ffffffc0004585ac netbsd:pcu_load +0x21c
fp ffffffc1252bfe70 trap_el0_sync() at ffffffc00006a918 netbsd:trap_el0_sync+0x108
fp ffffffc1252bfed0 el0_trap() at ffffffc0000685d0 netbsd:el0_trap

dmesg of the system: http://dmesgd.nycbug.org/index.cgi?do=view&id=4787

The system is built with:

MKPIE=          yes
MKSLJIT=        yes
MKDEBUG=        yes

It runs on a fully encrypted disk (mounted as /altroot).

# sysctl.conf
ddb.onpanic=1
kern.defcorename=/var/crash/%u/%n.core
kern.maxfiles=98304
security.pax.mprotect.enabled=1
security.pax.mprotect.global=1
security.pax.aslr.enabled=1
security.pax.aslr.global=1
security.pax.segvguard.enabled=1
security.pax.segvguard.global=0
security.pax.segvguard.max_crashes=10
security.pax.segvguard.expiry_timeout=120
security.pax.segvguard.suspend_timeout=600
net.bpf.jit=0
vfs.generic.magiclinks=1
hw.firmware.path=/libdata/firmware:/usr/libdata/firmware:/altroot/usr/pkg/libdata/firmware:/altroot/usr/pkg/libdata
>How-To-Repeat:
Run a tor relay for a while. Once it gets enough activity, the system will start crashing randomly.
>Fix:
Not known.