FC6 "modprobe loop" deadlock?

[Jan Andrejkovic]

Hello,

I have FC6 with default latest kernel and I configured encrypted swap (using
/etc/crypttab). Now when I need to use losetup to "mount" floppy disk image
as a loop device,
I should have module loop loaded first.

When I try "modprobe loop" modprobe hangs and starts to spawn its
copies, and then I see more and more modprobe processes eating all my
CPU time and swap space.
The only thing which saves my system from crash is to cancel the
modprobe or if I do "killall modprobe".

However I discovered that I can use insmod and it is working fine (also
losetup is fine) - so this is kind of a workaround:
# /sbin/insmod /lib/modules/2.6.20-1.2952.fc6/kernel/drivers/block/loop.ko
#

Once the module loop.ko is in the loaded, modprobe does not have a problem
(of course):
# /sbin/modprobe loop
#

However when I remove the loop.ko (rmmod loop), modprobe has a problem
again.

I have the same problem with both below kernels:
2.6.20-1.2952.fc6
2.6.20-1.2944.fc6

Am I doing something wrong here or is it a bug?

My hardware is VIA C7 and below you can find strace and lsmod outputs.

Thank you very much,

Jan

PS: Here are mentioned outputs::

#strace /sbin/modprobe loop
execve("/sbin/modprobe", ["/sbin/modprobe", "loop"], [/* 24
vars */]) = 0
brk(0)                                  = 0x9abe000
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0xb7fa0000
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or
directory)
open("/etc/ld.so.cache", O_RDONLY)      = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=66971, ...}) = 0
mmap2(NULL, 66971, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb7f8f000
close(3)                                = 0
open("/lib/libc.so.6", O_RDONLY)        = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0p\20\200"..., 512) =
512
fstat64(3, {st_mode=S_IFREG|0755, st_size=1576920, ...}) = 0
mmap2(0x487eb000, 1295780, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE,
3, 0) = 0x487eb000
mmap2(0x48922000, 12288, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x137) = 0x48922000
mmap2(0x48925000, 9636, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x48925000
close(3)                                = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0xb7f8e000
set_thread_area({entry_number:-1 -> 6, base_addr:0xb7f8e6c0, limit:1048575,
seg_32bit:1, contents:0, read_exec_only:0, limit_in_pages:1,
seg_not_present:0, useable:1}) = 0
mprotect(0x48922000, 8192, PROT_READ)   = 0
mprotect(0x468e6000, 4096, PROT_READ)   = 0
munmap(0xb7f8f000, 66971)               = 0
uname({sys="Linux", node="thsw", ...})  = 0
fstat64(2, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 0), ...}) = 0
brk(0)                                  = 0x9abe000
brk(0x9adf000)                          = 0x9adf000
open("/etc/modprobe.d", O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY) = 3
fstat64(3, {st_mode=S_IFDIR|0755, st_size=4096, ...}) = 0
fcntl64(3, F_SETFD, FD_CLOEXEC)         = 0
getdents(3, /* 5 entries */, 4096)      = 116
open("/etc/modprobe.d/blacklist",
O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY) = -1 ENOTDIR (Not a directory)
open("/etc/modprobe.d/blacklist", O_RDONLY) = 4
fstat64(4, {st_mode=S_IFREG|0644, st_size=809, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0xb7f9f000
read(4, "#\n# Listing a module here preven"..., 4096) = 809
read(4, "", 4096)                       = 0
close(4)                                = 0
munmap(0xb7f9f000, 4096)                = 0
open("/etc/modprobe.d/modprobe.conf.dist",
O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY) = -1 ENOTDIR (Not a directory)
open("/etc/modprobe.d/modprobe.conf.dist", O_RDONLY) = 4
fstat64(4, {st_mode=S_IFREG|0644, st_size=5717, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0xb7f9f000
read(4, "# default modutils aliases\nalias"..., 4096) = 4096
read(4, "l net-pf-3 /bin/true\ninstall net"..., 4096) = 1621
read(4, "", 4096)                       = 0
close(4)                                = 0
munmap(0xb7f9f000, 4096)                = 0
open("/etc/modprobe.d/blacklist-compat",
O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY) = -1 ENOTDIR (Not a directory)
open("/etc/modprobe.d/blacklist-compat", O_RDONLY) = 4
fstat64(4, {st_mode=S_IFREG|0644, st_size=833, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0xb7f9f000
read(4, "#\n# Listing a module here preven"..., 4096) = 833
read(4, "", 4096)                       = 0
close(4)                                = 0
munmap(0xb7f9f000, 4096)                = 0
getdents(3, /* 0 entries */, 4096)      = 0
close(3)                                = 0
open("/etc/modprobe.d", O_RDONLY)       = 3
fstat64(3, {st_mode=S_IFDIR|0755, st_size=4096, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0xb7f9f000
read(3, 0xb7f9f000, 4096)               = -1 EISDIR (Is a directory)
close(3)                                = 0
munmap(0xb7f9f000, 4096)                = 0
open("/etc/modprobe.conf", O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY) = -1
ENOTDIR (Not a directory)
open("/etc/modprobe.conf", O_RDONLY)    = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=432, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0xb7f9f000
read(3, "#Tofu:\ninstall loop /sbin/modpro"..., 4096) = 432
read(3, "", 4096)                       = 0
close(3)                                = 0
munmap(0xb7f9f000, 4096)                = 0
open("/lib/modules/2.6.20-1.2952.fc6/modules.dep", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=276791, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0xb7f9f000
read(3, "/lib/modules/2.6.20-1.2952.fc6/k"..., 4096) = 4096
read(3, "nls_cp857.ko:\n/lib/modules/2.6.2"..., 4096) = 4096
read(3, ".20-1.2952.fc6/kernel/net/802/p8"..., 4096) = 4096
read(3, "ernel/drivers/net/slhc.ko\n/lib/m"..., 4096) = 4096
read(3, "netfilter/x_tables.ko\n/lib/modul"..., 4096) = 4096
read(3, "ge/netfilter/ebtables.ko\n/lib/mo"..., 4096) = 4096
read(3, ".6.20-1.2952.fc6/kernel/net/netf"..., 4096) = 4096
read(3, "/lib/modules/2.6.20-1.2952.fc6/k"..., 4096) = 4096
read(3, "b/modules/2.6.20-1.2952.fc6/kern"..., 4096) = 4096
read(3, "-1.2952.fc6/kernel/net/netfilter"..., 4096) = 4096
read(3, "ules/2.6.20-1.2952.fc6/kernel/ne"..., 4096) = 4096
read(3, "/lib/modules/2.6.20-1.2952.fc6/k"..., 4096) = 4096
read(3, "vers/net/tokenring/olympic.ko:\n/"..., 4096) = 4096
read(3, "t/ieee80211/ieee80211_crypt.ko\n/"..., 4096) = 4096
read(3, "rda/irda.ko /lib/modules/2.6.20-"..., 4096) = 4096
read(3, "ib/modules/2.6.20-1.2952.fc6/ker"..., 4096) = 4096
read(3, "modules/2.6.20-1.2952.fc6/kernel"..., 4096) = 4096
read(3, ".fc6/kernel/drivers/i2c/i2c-core"..., 4096) = 4096
read(3, "/modules/2.6.20-1.2952.fc6/kerne"..., 4096) = 4096
read(3, "drivers/mtd/chips/chipreg.ko:\n/l"..., 4096) = 4096
read(3, "20-1.2952.fc6/kernel/drivers/mtd"..., 4096) = 4096
read(3, "mtd_blkdevs.ko /lib/modules/2.6."..., 4096) = 4096
read(3, "csi_transport_sas.ko /lib/module"..., 4096) = 4096
read(3, "2.6.20-1.2952.fc6/kernel/drivers"..., 4096) = 4096
read(3, "2952.fc6/kernel/drivers/infiniba"..., 4096) = 4096
read(3, "/drivers/media/video/compat_ioct"..., 4096) = 4096
read(3, "/2.6.20-1.2952.fc6/kernel/driver"..., 4096) = 4096
read(3, "/media/video/video-buf.ko /lib/m"..., 4096) = 4096
read(3, "-common.ko /lib/modules/2.6.20-1"..., 4096) = 4096
read(3, "media/dvb/frontends/isl6421.ko: "..., 4096) = 4096
read(3, "modules/2.6.20-1.2952.fc6/kernel"..., 4096) = 4096
read(3, "es/2.6.20-1.2952.fc6/kernel/driv"..., 4096) = 4096
read(3, ".ko /lib/modules/2.6.20-1.2952.f"..., 4096) = 4096
read(3, "es/2.6.20-1.2952.fc6/kernel/driv"..., 4096) = 4096
read(3, "lib/modules/2.6.20-1.2952.fc6/ke"..., 4096) = 4096
read(3, "common/ir-common.ko /lib/modules"..., 4096) = 4096
read(3, "ernel/drivers/media/video/v4l2-c"..., 4096) = 4096
read(3, "ko /lib/modules/2.6.20-1.2952.fc"..., 4096) = 4096
read(3, "/v4l1-compat.ko\n/lib/modules/2.6"..., 4096) = 4096
close(3)                                = 0
munmap(0xb7f9f000, 4096)                = 0
open("/lib/modules/2.6.20-1.2952.fc6/kernel/drivers/block/loop.ko", O_RDWR)
= 3
fcntl64(3, F_SETLKW, {type=F_WRLCK, whence=SEEK_SET, start=0, len=1}) = 0
open("/proc/modules", O_RDONLY)         = 4
fstat64(4, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0xb7f9f000
read(4, "autofs4 24261 2 - Live 0xf8dc600"..., 1024) = 1024
read(4, "onntrack, Live 0xf8cbf000\niptabl"..., 1024) = 1024
read(4, "7 1 asus_acpi, Live 0xf8b91000\na"..., 1024) = 1024
read(4, "ixer_oss,snd_pcm,snd_timer,snd_m"..., 1024) = 1024
read(4, "t3, Live 0xf8880000\nehci_hcd 341"..., 1024) = 125
read(4, "", 1024)                       = 0
close(4)                                = 0
munmap(0xb7f9f000, 4096)                = 0
close(3)                                = 0
rt_sigaction(SIGINT, {SIG_IGN}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGQUIT, {SIG_IGN}, {SIG_DFL}, 8) = 0
rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
clone(child_stack=0, flags=CLONE_PARENT_SETTID|SIGCHLD,
parent_tidptr=0xbfc382a4) = 20034
waitpid(20034,
!!!!! ^^^ Here it hangs and starts to fork itself

#---------------------------------------------------------------------------------------------------
# /sbin/lsmod
Module                  Size  Used by
autofs4                24261  2
f71805f                22085  0
hwmon                   7493  1 f71805f
eeprom                 11217  0
hidp                   23617  2
l2cap                  30657  5 hidp
bluetooth              57893  2 hidp,l2cap
sunrpc                153597  1
xt_conntrack            6849  3
nf_nat_ftp              7489  0
nf_conntrack_ftp       13761  1 nf_nat_ftp
xt_pkttype              5953  6
xt_limit                6721  17
ipt_LOG                10305  20
iptable_mangle          6977  0
iptable_nat            11461  1
nf_nat                 21997  2 nf_nat_ftp,iptable_nat
nf_conntrack_netbios_ns     7104  0
ipt_REJECT              8641  1
nf_conntrack_ipv4      21709  18 iptable_nat
xt_state                6593  13
nf_conntrack           62409  8
xt_conntrack,nf_nat_ftp,nf_conntrack_ftp,iptable_nat,nf_nat,nf_conntrack_netbios_ns,nf_conntrack_ipv4,xt_state
nfnetlink              10841  3 nf_nat,nf_conntrack_ipv4,nf_conntrack
iptable_filter          7105  1
ip_tables              16389  3 iptable_mangle,iptable_nat,iptable_filter
ip6t_REJECT             9537  1
xt_tcpudp               7233  22
ip6table_filter         6849  1
ip6_tables             17541  1 ip6table_filter
x_tables               18757  11
xt_conntrack,xt_pkttype,xt_limit,ipt_LOG,iptable_nat,ipt_REJECT,xt_state,ip_tables,ip6t_REJECT,xt_tcpudp,ip6_tables
ipv6                  275969  26 ip6t_REJECT
acpi_cpufreq           14281  0
sha256                 15297  0
aes                    31617  4
cbc                     8513  2
blkcipher               9665  1 cbc
dm_crypt               16969  1
dm_multipath           21833  0
raid0                  12225  3
video                  19909  0
sbs                    19073  0
i2c_ec                  9025  1 sbs
dock                   13977  0
button                 11857  0
battery                13893  0
asus_acpi              20445  0
backlight              10177  1 asus_acpi
ac                      9157  0
lp                     16265  0
snd_via82xx            31577  0
gameport               19401  1 snd_via82xx
snd_ac97_codec         93413  1 snd_via82xx
ac97_bus                6465  1 snd_ac97_codec
snd_seq_dummy           7877  0
snd_seq_oss            33601  0
snd_seq_midi_event     11201  1 snd_seq_oss
snd_seq                51249  5 snd_seq_dummy,snd_seq_oss,snd_seq_midi_event
snd_pcm_oss            43617  0
snd_mixer_oss          19393  1 snd_pcm_oss
snd_pcm                75205  3 snd_via82xx,snd_ac97_codec,snd_pcm_oss
snd_timer              25157  2 snd_seq,snd_pcm
snd_page_alloc         13769  2 snd_via82xx,snd_pcm
snd_mpu401_uart        12609  1 snd_via82xx
snd_rawmidi            26817  1 snd_mpu401_uart
snd_seq_device         11853  4
snd_seq_dummy,snd_seq_oss,snd_seq,snd_rawmidi
snd                    53829  11
snd_via82xx,snd_ac97_codec,snd_seq_oss,snd_seq,snd_pcm_oss,snd_mixer_oss,snd_pcm,snd_timer,snd_mpu401_uart,snd_rawmidi,snd_seq_device
i2c_viapro             12629  0
r8169                  33481  0
parport_pc             30053  1
soundcore              11681  1 snd
ohci1394               37489  0
via_rhine              28489  0
mii                     9409  1 via_rhine
ieee1394              294681  1 ohci1394
i2c_core               24897  3 eeprom,i2c_ec,i2c_viapro
parport                38537  2 lp,parport_pc
pcspkr                  7233  0
dm_snapshot            20849  0
dm_zero                 6209  0
dm_mirror              25301  0
dm_mod                 58253  24
dm_crypt,dm_multipath,dm_snapshot,dm_zero,dm_mirror
sata_via               14533  0
libata                104661  1 sata_via
sd_mod                 24129  0
scsi_mod              138093  2 libata,sd_mod
raid456               123473  0
xor                    18121  1 raid456
raid1                  26433  9
ext3                  125641  7
jbd                    60777  1 ext3
ehci_hcd               34125  0
ohci_hcd               23493  0
uhci_hcd               26705  0

[Chuck Ebbert]

On 06/01/2007 02:58 PM, Jan Andrejkovic wrote:
>  Hello,
>  
>  I have FC6 with default latest kernel and I configured encrypted swap
>  (using
>  /etc/crypttab). Now when I need to use losetup to "mount" floppy disk image
>  as a loop device,
>  I should have module loop loaded first.
>  
>  When I try "modprobe loop" modprobe hangs and starts to spawn its
>  copies, and then I see more and more modprobe processes eating all my
>  CPU time and swap space.
>  The only thing which saves my system from crash is to cancel the
>  modprobe or if I do "killall modprobe". 
You need to file a bug for this. And include the contents of
/etc/modprobe.conf in the report.

[Jan Andrejkovic]

Hello,

It is resolved now (!). I tried to solve one issue but I created another
one. I had a problem with "modprobe loop" under 2.6.20-1.2944.fc6 therefore
(as a part of the troubleshooting) I added below line into
/etc/modprobe.conf trying to force it to load at start:
install loop /sbin/modprobe loop; /bin/true

Becuase I used the same name (loop) twice in above line, I created the
loop...

However once I commented this line all if fine now.

Chuck - thank you for pointing me in the right direction.

I'm sorry for any confusion caused,

Jan

2007/6/1, Chuck Ebbert <cebbert(a)redhat.com&gt;:
>  On 06/01/2007 02:58 PM, Jan Andrejkovic wrote:
>  > Hello,
>  >
>  > I have FC6 with default latest kernel and I configured encrypted swap
>  > (using
>  > /etc/crypttab). Now when I need to use losetup to "mount" floppy disk
>  image
>  > as a loop device,
>  > I should have module loop loaded first.
>  >
>  > When I try "modprobe loop" modprobe hangs and starts to spawn its
>  > copies, and then I see more and more modprobe processes eating all my
>  > CPU time and swap space.
>  > The only thing which saves my system from crash is to cancel the
>  > modprobe or if I do "killall modprobe".
>
>  You need to file a bug for this. And include the contents of
>  /etc/modprobe.conf in the report.
>