Re: mysterious "recoverable" page faults

[David Young <dyoung%pobox.com@localhost>]

On Fri, Jan 18, 2008 at 11:56:40AM -0600, David Young wrote:
> Does anyone have an idea of what could cause these "recoverable"
> page faults?

Following are two sample faults.  The second came at least several
minutes after the first.  I had to 'ifconfig rtw0 down ; ifconfig rtw0
up' the wireless interface in the mean time---its DMA engine had gone
out to lunch, and yes I *do* suspect that DMA misbehavior is a factor.
I did not reboot the machine between the faults.

Dave

*** fault 1 ***

rtw0: tx fifo underflow
uvm_fault(0xc56cf6e4, 0, 1) -> 0xe
kernel: supervisor trap page fault, code=0
Stopped in pid 526.1 (hslsd) at netbsd:rtcache_free:    pushl   %ebp
db> bt
rtcache_free(5f5e5bf4,748dc35d,bc8d0026,27,24458d00) at netbsd:rtcache_free
?(c0731f00,0,c0587e88,0,c070e680) at 0x658df089
udp_output(c0731f00,c0587e58,c6932380,c013e2b0,48) at netbsd:udp_output+0x155
udp_usrreq(c05869a0,9,c0731f00,c0737c00,0) at netbsd:udp_usrreq+0x33a
sosend(c05869a0,c0737c00,c6a55b78,c0731f00,0) at netbsd:sosend+0x448
do_sys_sendmsg(c6932380,5,c6a55be8,0,c6a55c58) at netbsd:do_sys_sendmsg+0x337
sys_sendto(c6932380,c6a55c30,c6a55c58,0,7) at netbsd:sys_sendto+0x54
syscall(c6a55c78,bb9100b3,bb9000ab,bb91001f,bfbf001f) at netbsd:syscall+0x11d
db> show registers
ds          0x10
es          0x10
fs          0x30
gs          0x10
edi         0xc0731f9c
esi         0
ebp         0xc6a559fc
ebx         0xc0734ef8
edx         0xc6a559c4
ecx         0x3
eax         0
eip         0xc02b3cc0  rtcache_free
cs          0x8
eflags      0x10296
esp         0xc012c22b  ip_output+0x24b
ss          0x59c4
netbsd:rtcache_free:    pushl   %ebp
db> step
sip0: receive FIFO overrun
sip0: receive ring overrun
Stopped in pid 526.1 (hslsd) at netbsd:rtcache_free+0x1:        movl    %esp,%eb
p
db> show registers
ds          0x10
es          0x10
fs          0x30
gs          0x10
edi         0xc0731f9c
esi         0
ebp         0xc6a559fc
ebx         0xc0734ef8
edx         0xc6a559c4
ecx         0x3
eax         0
eip         0xc02b3cc1  rtcache_free+0x1
cs          0x8
eflags      0x296
esp         0xc6a5596c
ss          0x10
netbsd:rtcache_free+0x1:        movl    %esp,%ebp
db> continue 
sip0: receive FIFO overrun
sip0: receive ring overrun
rtw0: tx fifo underflow
rtw0: tx fifo underflow

rtw0: tx fifo underflow
rtw0: tx fifo underflow
rtw0: tx fifo underflow
rtw0: tx fifo underflow

*** fault 2 ***

uvm_fault(0xc56cf6e4, 0, 1) -> 0xe
kernel: supervisor trap page fault, code=0
Stopped in pid 526.1 (hslsd) at netbsd:rtcache_free:    pushl   %ebp
db> ci
No such command
db> iq c-i0
No such command
db> w0 9[Cnt        bt    bt
rtcache_free(5f5e5bf4,748dc35d,bc8d0026,27,24458d00) at netbsd:rtcache_free
?(c0729f00,0,c0587e88,0,c070e680) at 0x658df089
udp_output(c0729f00,c0587e58,c6932380,c013e2b0,48) at netbsd:udp_output+0x155
udp_usrreq(c05869a0,9,c0729f00,c073dd00,0) at netbsd:udp_usrreq+0x33a
sosend(c05869a0,c073dd00,c6a55b78,c0729f00,0) at netbsd:sosend+0x448
do_sys_sendmsg(c6932380,5,c6a55be8,0,c6a55c58) at netbsd:do_sys_sendmsg+0x337
sys_sendto(c6932380,c6a55c30,c6a55c58,0,bb967000) at netbsd:sys_sendto+0x54
syscall(c6a55c78,b3,ab,1f,bfbf001f) at netbsd:syscall+0x11d
db> show registers
ds          0x10
es          0x10
fs          0x30
gs          0x10
edi         0xc0729f9c
esi         0
ebp         0xc6a559fc
ebx         0xc0734ef8
edx         0xc6a559c4
ecx         0x3
eax         0
eip         0xc02b3cc0  rtcache_free
cs          0x8
eflags      0x10296
esp         0xc012c22b  ip_output+0x24b
ss          0x59c4
netbsd:rtcache_free:    pushl   %ebp
db> step 
sip0: receive FIFO overrun
sip0: receive ring overrun
sip0: receive FIFO overrun
Stopped in pid 526.1 (hslsd) at netbsd:rtcache_free+0x1:        movl    %esp,%eb
p
db> bt 
rtcache_free(c0729f00,0,c0587e88,0,c070e680) at netbsd:rtcache_free+0x1
udp_output(c0729f00,c0587e58,c6932380,c013e2b0,48) at netbsd:udp_output+0x155
udp_usrreq(c05869a0,9,c0729f00,c073dd00,0) at netbsd:udp_usrreq+0x33a
sosend(c05869a0,c073dd00,c6a55b78,c0729f00,0) at netbsd:sosend+0x448
do_sys_sendmsg(c6932380,5,c6a55be8,0,c6a55c58) at netbsd:do_sys_sendmsg+0x337
sys_sendto(c6932380,c6a55c30,c6a55c58,0,bb967000) at netbsd:sys_sendto+0x54
syscall(c6a55c78,b3,ab,1f,bfbf001f) at netbsd:syscall+0x11d
db> show registers
ds          0x10
es          0x10
fs          0x30
gs          0x10
edi         0xc0729f9c
esi         0
ebp         0xc6a559fc
ebx         0xc0734ef8
edx         0xc6a559c4
ecx         0x3
eax         0
eip         0xc02b3cc1  rtcache_free+0x1
cs          0x8
eflags      0x296
esp         0xc6a5596c
ss          0x10
netbsd:rtcache_free+0x1:        movl    %esp,%ebp
db> 

-- 
David Young             OJC Technologies
dyoung%ojctech.com@localhost      Urbana, IL * (217) 278-3933 ext 24