# Summary
Bug hit again, workaround works again, this time with a strace.
I suspect the workaround has a drawback: the characters it eats are lost for
the script.
Next time I'll try dd to "lose" only one character.
Thank you for your attention.
# Details
The bug has hit again.
Here is a selected portion of
strace head /proc/7514/fd/4
open("/proc/7514/fd/4", O_RDONLY) = 3
read(3, "\n", 8192) = 1
fstat(1, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 14), ...}) = 0
write(1, "\n", 1
) = 1
read(3, "a", 8192) = 1
read(3, "a", 8192) = 1
read(3, "*", 8192) = 1
read(3, "\177", 8192) = 1
read(3, "e", 8192) = 1
read(3, "e", 8192) = 1
read(3, "\r", 8192) = 1
read(3, ^Cstrace: Process 14679 detached
<detached ...>
The characters return by read() are what I typed on the terminal hosting
the stuck /usr/bin/script.
I think that script unlocked itself (i.e. the bug went away) as soon as
the first read() returned, but I'm not sure.
Thank you for your attention.
strace head /proc/7514/fd/4
execve("/usr/bin/head", ["head", "/proc/7514/fd/4"], [/* 31 vars */]) = 0
brk(NULL) = 0x18a8000
access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0x7ff26a1f6000
access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=123250, ...}) = 0
mmap(NULL, 123250, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7ff26a1d7000
close(3) = 0
access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
open("/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0`\t\2\0\0\0\0\0"...,
832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=1868984, ...}) = 0
mmap(NULL, 3971584, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) =
0x7ff269c09000
mprotect(0x7ff269dc9000, 2097152, PROT_NONE) = 0
mmap(0x7ff269fc9000, 24576, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1c0000) = 0x7ff269fc9000
mmap(0x7ff269fcf000, 14848, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7ff269fcf000
close(3) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0x7ff26a1d6000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0x7ff26a1d5000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0x7ff26a1d4000
arch_prctl(ARCH_SET_FS, 0x7ff26a1d5700) = 0
mprotect(0x7ff269fc9000, 16384, PROT_READ) = 0
mprotect(0x608000, 4096, PROT_READ) = 0
mprotect(0x7ff26a1f8000, 4096, PROT_READ) = 0
munmap(0x7ff26a1d7000, 123250) = 0
brk(NULL) = 0x18a8000
brk(0x18c9000) = 0x18c9000
open("/usr/lib/locale/locale-archive", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=3001856, ...}) = 0
mmap(NULL, 3001856, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7ff26992c000
close(3) = 0
open("/proc/7514/fd/4", O_RDONLY) = 3
read(3, "\n", 8192) = 1
fstat(1, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 14), ...}) = 0
write(1, "\n", 1
) = 1
read(3, "a", 8192) = 1
read(3, "a", 8192) = 1
read(3, "*", 8192) = 1
read(3, "\177", 8192) = 1
read(3, "e", 8192) = 1
read(3, "e", 8192) = 1
read(3, "\r", 8192) = 1
read(3, ^Cstrace: Process 14679 detached
<detached ...>
--
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to util-linux in Ubuntu.
https://bugs.launchpad.net/bugs/1558236
Title:
/usr/bin/script freezes and eats all CPU, has to be killed, which
kills shell and programs inside
Status in util-linux package in Ubuntu:
New
Bug description:
# Context
I've been using /usr/bin/script quite a lot for about 4 years (since
about Ubuntu 12.04, maybe before). It always worked without problem.
I'm using several script instance most of the time, in several
terminals.
Reproducible: randomly, once every few days.
Problem happens since Ubuntu 16.04. Never seen before (12.04 12.10
13.04 13.10 14.04 14.10 15.04 15.10).
# Expected
Continued operation, terminal running programs normally, little CPU
used.
# Observed
Suddenly, terminal freezes.
Other tabs of same terminal window not affected.
Top shows script consumes 100% CPU.
Strace shows an endless stream of this line:
poll([{fd=4, events=POLLIN}], 1, 10) = 1 ([{fd=4, revents=POLLIN}])
/proc/*/fd shows what file descriptor it is:
total 0
dr-x------ 2 stephane stephane 0 mars 16 20:03 .
dr-xr-xr-x 9 stephane stephane 0 mars 16 20:03 ..
lrwx------ 1 stephane stephane 64 mars 16 20:15 0 -> /dev/pts/17 (deleted)
lrwx------ 1 stephane stephane 64 mars 16 20:15 1 -> /dev/pts/17 (deleted)
lrwx------ 1 stephane stephane 64 mars 16 20:03 2 -> /dev/pts/17 (deleted)
lrwx------ 1 stephane stephane 64 mars 16 20:15 3 -> /dev/ptmx
lrwx------ 1 stephane stephane 64 mars 16 20:15 4 -> /dev/pts/21
lrwx------ 1 stephane stephane 64 mars 16 20:15 5 -> anon_inode:[signalfd]
l-wx------ 1 stephane stephane 64 mars 16 20:15 6 -> /somewhere/mylogfile.txt
l-wx------ 1 stephane stephane 64 mars 16 20:15 7 ->
/somewhere/mylogfile_timings.txt
What can we do?
ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: bsdutils 1:2.27.1-6ubuntu1
ProcVersionSignature: Ubuntu 4.4.0-13.29-generic 4.4.5
Uname: Linux 4.4.0-13-generic x86_64
ApportVersion: 2.20-0ubuntu3
Architecture: amd64
CurrentDesktop: XFCE
Date: Wed Mar 16 20:04:02 2016
ExecutablePath: /usr/bin/script
InstallationDate: Installed on 2016-02-03 (41 days ago)
InstallationMedia: Xubuntu 16.04 LTS "Xenial Xerus" - Alpha amd64 (20160203)
SourcePackage: util-linux
UpgradeStatus: No upgrade log present (probably fresh install)
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/util-linux/+bug/1558236/+subscriptions
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