[DragonFlyBSD - Bug #2506] panic: unmount: dangling vnode running poudriere

[Venkatesh Srinivas via Redmine <bugtracker-admin@xxxxxxxxxxxxxxxxxxxxx>]

Issue #2506 has been updated by vsrinivas.


At a first look, it seemed like a procfs mount was being unmounted
and the test that there were no vnodes linked in to the mount
tripped. However in the core, the vnode list on the procfs mount was
empty.

I think there is a race between dounmount() and insmntque(, NULL)
removing vnodes from a mount. dounmount is synchronizing via the
per-mount lockmgr, while insmntque() expects the vnode list to be
protected by the mntvnode token. Could you try taking the
mntvnode_token throughout the span of the dounmount() function?

Thanks,
-- vs;
----------------------------------------
Bug #2506: panic: unmount: dangling vnode running poudriere
http://bugs.dragonflybsd.org/issues/2506

Author: ftigeot
Status: New
Priority: Normal
Assignee: 
Category: 
Target version: 


I was running 4 poudriere jobs on a Xeon-E3 (8 threads) / DragonFly 3.3 system and it panicked after 30 hours

Backtrace:

(kgdb) #0  _get_mycpu () at ./machine/thread.h:69
#1  md_dumpsys (di=<optimized out>)
    at /usr/src/sys/platform/pc64/x86_64/dump_machdep.c:265
#2  0xffffffff804f5d12 in dumpsys () at /usr/src/sys/kern/kern_shutdown.c:913
#3  0xffffffff804f6376 in boot (howto=260)
    at /usr/src/sys/kern/kern_shutdown.c:373
#4  0xffffffff804f662d in panic (fmt=0xffffffff80906deb "%s")
    at /usr/src/sys/kern/kern_shutdown.c:819
#5  0xffffffff808b6408 in trap_fatal (frame=0xffffffe2cb503628, 
    eva=<optimized out>) at /usr/src/sys/platform/pc64/x86_64/trap.c:1029
#6  0xffffffff808b6f11 in trap (frame=0xffffffe2cb503628)
    at /usr/src/sys/platform/pc64/x86_64/trap.c:754
#7  0xffffffff808a0cdf in calltrap ()
    at /usr/src/sys/platform/pc64/x86_64/exception.S:188
#8  0xffffffff808b0eb9 in db_read_bytes (addr=7165064483209180471, size=8, 
    data=0xffffffe2cb503708 "")
    at /usr/src/sys/platform/pc64/x86_64/db_interface.c:240
#9  0xffffffff802a735d in db_get_value (addr=7165064483209180471, size=8, 
    is_signed=0) at /usr/src/sys/ddb/db_access.c:58
#10 0xffffffff808b1b55 in db_nextframe (ip=<optimized out>, 
    fp=<optimized out>) at /usr/src/sys/platform/pc64/x86_64/db_trace.c:234
#11 db_stack_trace_cmd (addr=<optimized out>, have_addr=<optimized out>, 
    count=<optimized out>, modif=<optimized out>)
    at /usr/src/sys/platform/pc64/x86_64/db_trace.c:440
#12 0xffffffff808b1d17 in print_backtrace (count=-883935480)
    at /usr/src/sys/platform/pc64/x86_64/db_trace.c:452
#13 0xffffffff804f65f8 in panic (
    fmt=0xffffffff8097713b "unmount: dangling vnode")
    at /usr/src/sys/kern/kern_shutdown.c:812
#14 0xffffffff80577a57 in dounmount (mp=0xffffffe27a209700, flags=-883935000)
    at /usr/src/sys/kern/vfs_syscalls.c:807
#15 0xffffffff80577c2c in sys_unmount (uap=0xffffffe2cb503a08)
    at /usr/src/sys/kern/vfs_syscalls.c:622
#16 0xffffffff808b7683 in syscall2 (frame=0xffffffe2cb503ab8)
    at /usr/src/sys/platform/pc64/x86_64/trap.c:1238
#17 0xffffffff808a0f2b in Xfast_syscall ()
    at /usr/src/sys/platform/pc64/x86_64/exception.S:323
#18 0x000000000000002b in ?? ()
Backtrace stopped: previous frame inner to this frame (corrupt stack?)


Core dump and associated files available on leaf:~ftigeot/crash/crash.dangling_vnode



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