Date: Wed, 12 Feb 2014 19:06:59 +0200 From: Andriy Gapon <avg@FreeBSD.org> To: freebsd-stable List <freebsd-stable@FreeBSD.org> Subject: panic: vm_page_unwire: page 0xfffffe104d4c9cd8's wire count is zero Message-ID: <52FBAA33.9010005@FreeBSD.org>
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I've got an odd panic on a stable/9 system:
(kgdb) bt
#0 doadump (textdump=1) at /usr/src/sys/kern/kern_shutdown.c:266
#1 0xffffffff808f9814 in kern_reboot (howto=260) at
/usr/src/sys/kern/kern_shutdown.c:449
#2 0xffffffff808f9d07 in panic (fmt=0x1 <Address 0x1 out of bounds>) at
/usr/src/sys/kern/kern_shutdown.c:637
#3 0xffffffff80b81b45 in vm_page_unwire (m=<value optimized out>,
activate=<value optimized out>) at /usr/src/sys/vm/vm_page.c:2018
#4 0xffffffff80b6e062 in vm_fault_unwire (map=<value optimized out>,
start=<value optimized out>, end=4202496, fictitious=0) at
/usr/src/sys/vm/vm_fault.c:1238
#5 0xffffffff80b7617f in vm_map_delete (map=0xfffffe01a8eeaaf0, start=4096,
end=140737488355328) at /usr/src/sys/vm/vm_map.c:2713
#6 0xffffffff80b764e1 in vm_map_remove (map=0xfffffe01a8eeaaf0, start=4096,
end=140737488355328) at /usr/src/sys/vm/vm_map.c:2903
#7 0xffffffff80b79837 in vmspace_exit (td=0xfffffe01b8056490) at
/usr/src/sys/vm/vm_map.c:350
#8 0xffffffff808c2f00 in exit1 (td=0xfffffe01b8056490, rv=0) at
/usr/src/sys/kern/kern_exit.c:322
#9 0xffffffff808c424e in sys_sys_exit (td=<value optimized out>, uap=<value
optimized out>) at /usr/src/sys/kern/kern_exit.c:121
#10 0xffffffff80cec26a in amd64_syscall (td=0xfffffe01b8056490, traced=0) at
subr_syscall.c:135
#11 0xffffffff80cd64c7 in Xfast_syscall () at
/usr/src/sys/amd64/amd64/exception.S:391
(kgdb) p *entry
$2 = {
prev = 0xfffffe01a8eeaaf0,
next = 0xfffffe01a8f02500,
left = 0x0,
right = 0xfffffe01b805f800,
start = 4194304,
end = 4202496,
avail_ssize = 0,
adj_free = 2093056,
max_free = 140703107510272,
object = {
vm_object = 0xfffffe025d23b0e8,
sub_map = 0xfffffe025d23b0e8
},
offset = 0,
eflags = 1068, // MAP_ENTRY_COW | MAP_ENTRY_NEEDS_COPY | MAP_ENTRY_USER_WIRED
| MAP_ENTRY_NOCOREDUMP
protection = 5 '\005',
max_protection = 7 '\a',
inheritance = 1 '\001',
read_ahead = 0 '\0',
wired_count = 1,
next_read = 2,
cred = 0x0,
wiring_thread = 0x0
}
(kgdb) p *entry->object.vm_object
$4 = {
mtx = {
lock_object = {
lo_name = 0xffffffff80fc2940 "vm object",
lo_flags = 21168128,
lo_data = 0,
lo_witness = 0x0
},
mtx_lock = 4
},
object_list = {
tqe_next = 0xfffffe027019c828,
tqe_prev = 0xfffffe0263ca0a18
},
shadow_head = {
lh_first = 0x0
},
shadow_list = {
le_next = 0xfffffe0263d24828,
le_prev = 0xfffffe0029189a28
},
memq = {
tqh_first = 0xfffffe104d4c9cd8,
tqh_last = 0xfffffe10520616b0
},
root = 0xfffffe104d4c9cd8,
size = 3,
generation = 1,
ref_count = 1,
shadow_count = 0,
memattr = 6 '\006',
type = 2 '\002', // OBJT_VNODE
flags = 4100, // OBJ_ACTIVE | OBJ_COLORED
pg_color = 0,
pad1 = 0,
resident_page_count = 2,
backing_object = 0x0,
backing_object_offset = 0,
pager_object_list = {
tqe_next = 0x0,
tqe_prev = 0x0
},
rvq = {
lh_first = 0x0
},
cache = 0x0,
handle = 0xfffffe0263c4b000,
un_pager = {
vnp = {
vnp_size = 9872,
writemappings = 0
},
devp = {
devp_pglist = {
tqh_first = 0x2690,
tqh_last = 0x0
},
ops = 0x0
},
sgp = {
sgp_pglist = {
tqh_first = 0x2690,
tqh_last = 0x0
}
},
swp = {
swp_bcount = 9872
}
},
cred = 0x0,
charge = 0,
paging_in_progress = 0
}
(kgdb) p *(vnode_t)entry->object.vm_object->handle
$6 = {
v_type = VREG,
v_tag = 0xffffffff8185f1ac "zfs",
v_op = 0xffffffff8186b280,
v_data = 0xfffffe0263c62000,
v_mount = 0xfffffe001cec09a8,
v_nmntvnodes = {
tqe_next = 0xfffffe025d8035f8,
tqe_prev = 0xfffffe027038a620
},
v_un = {
vu_mount = 0x0,
vu_socket = 0x0,
vu_cdev = 0x0,
vu_fifoinfo = 0x0
},
v_hashlist = {
le_next = 0x0,
le_prev = 0x0
},
v_hash = 2157506860,
v_cache_src = {
lh_first = 0x0
},
v_cache_dst = {
tqh_first = 0x0,
tqh_last = 0xfffffe0263c4b060
},
v_cache_dd = 0x0,
v_cstart = 0,
v_lasta = 0,
v_lastw = 0,
v_clen = 0,
v_lock = {
lock_object = {
lo_name = 0xffffffff8185f1ac "zfs",
lo_flags = 108724224,
lo_data = 0,
lo_witness = 0x0
},
lk_lock = 1,
lk_exslpfail = 0,
lk_timo = 51,
lk_pri = 96
},
v_interlock = {
lock_object = {
lo_name = 0xffffffff80f9ae39 "vnode interlock",
lo_flags = 16973824,
lo_data = 0,
lo_witness = 0x0
},
mtx_lock = 4
},
v_vnlock = 0xfffffe0263c4b098,
v_holdcnt = 3,
v_usecount = 2,
v_iflag = 512, // VI_ACTIVE
v_vflag = 32, // VV_TEXT
v_writecount = 0,
v_actfreelist = {
tqe_next = 0xfffffe027038a5f8,
tqe_prev = 0xfffffe0263c7d708
},
v_bufobj = {
bo_mtx = {
lock_object = {
lo_name = 0xffffffff80f9ae49 "bufobj interlock",
lo_flags = 16973824,
lo_data = 0,
lo_witness = 0x0
},
mtx_lock = 4
},
bo_clean = {
bv_hd = {
tqh_first = 0x0,
tqh_last = 0xfffffe0263c4b140
},
bv_root = 0x0,
bv_cnt = 0
},
bo_dirty = {
bv_hd = {
tqh_first = 0x0,
tqh_last = 0xfffffe0263c4b160
},
bv_root = 0x0,
bv_cnt = 0
},
bo_numoutput = 0,
bo_flag = 0,
bo_ops = 0xffffffff81316f20,
bo_bsize = 131072,
bo_object = 0xfffffe025d23b0e8,
bo_synclist = {
le_next = 0x0,
le_prev = 0x0
},
bo_private = 0xfffffe0263c4b000,
__bo_vnode = 0xfffffe0263c4b000
},
v_pollinfo = 0x0,
v_label = 0x0,
v_lockf = 0x0,
v_rl = {
rl_waiters = {
tqh_first = 0x0,
tqh_last = 0xfffffe0263c4b1e0
},
rl_currdep = 0x0
},
v_fullpath = '\0' <repeats 1023 times>
}
(kgdb) i loc
pa = <value optimized out>
va = 4194304
m = 0xfffffe104d4c9cd8
pmap = 0xfffffe01a8eeac28
(kgdb) p *m
$7 = {
pageq = {
tqe_next = 0xfffffe106fb96e68,
tqe_prev = 0xfffffe10520616a0
},
listq = {
tqe_next = 0xfffffe10520616a0,
tqe_prev = 0xfffffe025d23b130
},
left = 0x0,
right = 0xfffffe10520616a0,
object = 0xfffffe025d23b0e8,
pindex = 0,
phys_addr = 41917632512,
md = {
pv_list = {
tqh_first = 0xfffffe02703de0b8,
tqh_last = 0xfffffe02703de0c0
},
pat_mode = 6
},
queue = 1 '\001',
segind = 3 '\003',
hold_count = 0,
order = 13 '\r',
pool = 0 '\0',
cow = 0,
wire_count = 0,
aflags = 0 '\0',
flags = 0 '\0',
oflags = 0,
act_count = 64 '@',
busy = 0 '\0',
valid = 255 '�',
dirty = 0 '\0'
}
(kgdb) p *m->right
$8 = {
pageq = {
tqe_next = 0xfffffe104d4c9cd8,
tqe_prev = 0xfffffe105187aab8
},
listq = {
tqe_next = 0x0,
tqe_prev = 0xfffffe104d4c9ce8
},
left = 0x0,
right = 0x0,
object = 0xfffffe025d23b0e8,
pindex = 1,
phys_addr = 44623183872,
md = {
pv_list = {
tqh_first = 0xfffffe02703de0a0,
tqh_last = 0xfffffe02703de0a8
},
pat_mode = 6
},
queue = 1 '\001',
segind = 3 '\003',
hold_count = 0,
order = 13 '\r',
pool = 0 '\0',
cow = 0,
wire_count = 0,
aflags = 0 '\0',
flags = 0 '\0',
oflags = 0,
act_count = 64 '@',
busy = 0 '\0',
valid = 255 '�',
dirty = 0 '\0'
}
(kgdb) p *m->md.pv_list.tqh_first
$9 = {
pv_va = 4194304,
pv_list = {
tqe_next = 0x0,
tqe_prev = 0xfffffe104d4c9d20
}
}
Everything looks pretty consistent and sane to me. Except, of course, for
wire_count in both resident pages.
The process in question is watchdogd which seems to mlockall(MCL_CURRENT |
MCL_FUTURE) and that explains why the mapping is wired.
--
Andriy Gapon
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