'ps u' hangs: reason/cause?

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1

Hi Gurus,
I will appreciate any tips to work out what is happening in the following…

I noticed that Yast won’t start from the desktop. In trying to work out what was running I discovered that ‘ps u’ in fact ‘hangs’. Specifically

# ps u
USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root      3235  1.0  2.9  67480 61452 tty7     RLs+ Nov25  36:31 /usr/bin/Xorg -br -nolisten tcp :0 vt7 -aut
root      3889  0.0  0.0   2152   652 tty1     Ss+  Nov25   0:00 /sbin/mingetty --noclear tty1
root      3891  0.0  0.0   2152   652 tty2     Ss+  Nov25   0:00 /sbin/mingetty tty2
root      3893  0.0  0.0   2152   632 tty3     Ss+  Nov25   0:00 /sbin/mingetty tty3
root      3895  0.0  0.0   2152   632 tty4     Ss+  Nov25   0:00 /sbin/mingetty tty4
root      3902  0.0  0.0   2152   628 tty5     Ss+  Nov25   0:00 /sbin/mingetty tty5
root      3904  0.0  0.0   2152   632 tty6     Ss+  Nov25   0:00 /sbin/mingetty tty6

Then I have to hit CTL+c
However, the following commands do not hang:

ps ax
ps x
ps a

But these commands do hang if I add ‘u’ to any of the options/switches

I appreciate any tips/suggestions on how to work out what might be going wrong.

Cheers
Mark

2

adding some detail suggestsed elsewhere…


strace ps u

<snip>
......
</snip>

socket(PF_INET, SOCK_STREAM, IPPROTO_IP) = 7
setsockopt(7, SOL_SOCKET, SO_KEEPALIVE, [1], 4) = 0
setsockopt(7, SOL_TCP, TCP_NODELAY, [1], 4) = 0
fcntl64(7, F_GETFL)                     = 0x2 (flags O_RDWR)
fcntl64(7, F_SETFL, O_RDWR|O_NONBLOCK)  = 0
connect(7, {sa_family=AF_INET, sin_port=htons(389), sin_addr=inet_addr("127.0.0.1")}, 16) = -1 EINPROGRESS (Operation now in progress)
poll({fd=7, events=POLLOUT|POLLERR|POLLHUP, revents=POLLOUT}], 1, 30000) = 1
getpeername(7, {sa_family=AF_INET, sin_port=htons(389), sin_addr=inet_addr("127.0.0.1")}, [16]) = 0
fcntl64(7, F_GETFL)                     = 0x802 (flags O_RDWR|O_NONBLOCK)
fcntl64(7, F_SETFL, O_RDWR)             = 0
time(NULL)                              = 1227780032
time(NULL)                              = 1227780032
write(7, "0\f\2\1\1`\7\2\1\3\4\0\200\0", 14) = 14
gettimeofday({1227780032, 318107}, NULL) = 0
poll({fd=7, events=POLLIN|POLLPRI|POLLERR|POLLHUP}], 1, 30000) = 0
write(7, "0\6\2\1\2P\1\1", 8)           = 8
time(NULL)                              = 1227780062
time(NULL)                              = 1227780062
stat64("/etc/localtime", {st_mode=S_IFREG|0644, st_size=2183, ...}) = 0
socket(PF_FILE, SOCK_DGRAM, 0)          = 8
fcntl64(8, F_SETFD, FD_CLOEXEC)         = 0
connect(8, {sa_family=AF_FILE, path="/dev/log"}, 110) = 0
send(8, "&lt;14&gt;Nov 27 21:01:02 ps: nss_ldap"..., 107, MSG_NOSIGNAL

Not sure if that gives a clue?

3

Are you using LDAP to resolve user accounts?

4

Yes I am, the ldap server is running on this laptop - which is also a client. I am using ldap for some VM testing…

Mark

5

Looks like LDAP is blocking on the lookup.

6

Hmm, this is wierd…

service ldap restart

runs fine.
I went to check /var/log/messages and discovered it also hangs without printing any output.

Using strace the tail looks like:

strace tail -f /var/log/messages

execve("/usr/bin/tail", "tail", "-f", "/var/log/messages"], /* 62 vars */]) = 0
brk(0)                                  = 0x8054000
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=158225, ...}) = 0
mmap2(NULL, 158225, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb806b000
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\0Pg\1\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0755, st_size=1410320, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb806a000
mmap2(NULL, 1320528, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb7f27000
fadvise64(3, 0, 1320528, POSIX_FADV_WILLNEED) = 0
mmap2(0xb8064000, 12288, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x13d) = 0xb8064000
mmap2(0xb8067000, 9808, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xb8067000
close(3)                                = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7f26000
set_thread_area({entry_number:-1 -> 6, base_addr:0xb7f266c0, limit:1048575, seg_32bit:1, contents:0, read_exec_only:0, limit_in_pages:1, seg_not_present:0, useable:1}) = 0
open("/dev/urandom", O_RDONLY)          = 3
read(3, "\265\253s\5", 4)               = 4
close(3)                                = 0
mprotect(0xb8064000, 8192, PROT_READ)   = 0
mprotect(0x8052000, 4096, PROT_READ)    = 0
mprotect(0xb80ad000, 4096, PROT_READ)   = 0
munmap(0xb806b000, 158225)              = 0
brk(0)                                  = 0x8054000
brk(0x8075000)                          = 0x8075000
open("/usr/lib/locale/locale-archive", O_RDONLY|O_LARGEFILE) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/locale.alias", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=2512, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb8091000
read(3, "# Locale name alias data base.
#"..., 4096) = 2512
read(3, "", 4096)                       = 0
close(3)                                = 0
munmap(0xb8091000, 4096)                = 0
open("/usr/lib/locale/en_US.UTF-8/LC_CTYPE", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/lib/locale/en_US.utf8/LC_CTYPE", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=254076, ...}) = 0
mmap2(NULL, 254076, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb7ee7000
close(3)                                = 0
open("/usr/lib/gconv/gconv-modules.cache", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=26040, ...}) = 0
mmap2(NULL, 26040, PROT_READ, MAP_SHARED, 3, 0) = 0xb808b000
close(3)                                = 0
open("/var/log/messages", O_RDONLY|O_LARGEFILE) = 3
fstat64(3, {st_mode=S_IFREG|0640, st_size=0, ...}) = 0
_llseek(3, 0, [0], SEEK_CUR)            = 0
_llseek(3, 0, [0], SEEK_END)            = 0
_llseek(3, 0, [0], SEEK_SET)            = 0
read(3, "", 8192)                       = 0
fstat64(3, {st_mode=S_IFREG|0640, st_size=0, ...}) = 0
fcntl64(3, F_GETFL)                     = 0x8000 (flags O_RDONLY|O_LARGEFILE)
fcntl64(3, F_SETFL, O_RDONLY|O_NONBLOCK|O_LARGEFILE) = 0
fstat64(3, {st_mode=S_IFREG|0640, st_size=0, ...}) = 0
nanosleep({1, 0}, NULL)                 = 0
fstat64(3, {st_mode=S_IFREG|0640, st_size=0, ...}) = 0
nanosleep({1, 0}, NULL)                 = 0
fstat64(3, {st_mode=S_IFREG|0640, st_size=0, ...}) = 0
nanosleep({1, 0}, NULL)                 = 0
fstat64(3, {st_mode=S_IFREG|0640, st_size=0, ...}) = 0
nanosleep({1, 0}, NULL)                 = 0
fstat64(3, {st_mode=S_IFREG|0640, st_size=0, ...}) = 0
nanosleep({1, 0}, NULL)                 = 0
fstat64(3, {st_mode=S_IFREG|0640, st_size=0, ...}) = 0
nanosleep({1, 0}, NULL)                 = 0
fstat64(3, {st_mode=S_IFREG|0640, st_size=0, ...}) = 0
nanosleep({1, 0}, NULL)                 = 0
fstat64(3, {st_mode=S_IFREG|0640, st_size=0, ...}) = 0
nanosleep({1, 0}, NULL)                 = 0
fstat64(3, {st_mode=S_IFREG|0640, st_size=0, ...}) = 0
nanosleep({1, 0}, ^C <unfinished ...>

Any ideas?

Mark

7

Why not turn off LDAP lookup to see if it unblocks things? Then you will know for sure if it’s LDAP.