[Bug 1553353] Re: tail'ing a file in a script session hangs

[Simon Déziel]

** Description changed:

  Steps to reproduce:
  
  1) Start script session (same issue when script is saving to /dev/null)
  script # or: script /dev/null
  2) Tail a file
- tail -f /var/log/syslog
+ tailf /var/log/syslog
  3) Press "Enter" 2 times
  4) Notice the script process taking 100% CPU
  
- This regression is rather new but I don't know which update introduced
- it. Reverting util-linux/bsdutils to the previous version doesn't help
- so maybe it's not even script's fault. tail/coreutils hasn't been update
- in a long time so I'm not sure who's fault it is. I can reproduce the
- problem with kernel 4.4.0-9-generic and 4.4.0-10-generic.
- 
+ This regression was introduced upstream by this commit:
+ https://git.kernel.org/cgit/utils/util-linux/util-
+ linux.git/commit/?id=54c6611d6f7b73609a5331f4d0bcf63c4af6429e
  
  $ lsb_release -rd
  Description:	Ubuntu Xenial Xerus (development branch)
  Release:	16.04
  
  $ apt-cache policy util-linux bsdutils coreutils
  util-linux:
-   Installed: 2.27.1-4ubuntu1
-   Candidate: 2.27.1-4ubuntu1
-   Version table:
-  *** 2.27.1-4ubuntu1 500
-         500 http://archive.ubuntu.com/ubuntu xenial-proposed/main amd64 Packages
-         100 /var/lib/dpkg/status
-      2.27.1-3ubuntu1 500
-         500 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages
+   Installed: 2.27.1-4ubuntu1
+   Candidate: 2.27.1-4ubuntu1
+   Version table:
+  *** 2.27.1-4ubuntu1 500
+         500 http://archive.ubuntu.com/ubuntu xenial-proposed/main amd64 Packages
+         100 /var/lib/dpkg/status
+      2.27.1-3ubuntu1 500
+         500 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages
  bsdutils:
-   Installed: 1:2.27.1-4ubuntu1
-   Candidate: 1:2.27.1-4ubuntu1
-   Version table:
-  *** 1:2.27.1-4ubuntu1 500
-         500 http://archive.ubuntu.com/ubuntu xenial-proposed/main amd64 Packages
-         100 /var/lib/dpkg/status
-      1:2.27.1-3ubuntu1 500
-         500 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages
+   Installed: 1:2.27.1-4ubuntu1
+   Candidate: 1:2.27.1-4ubuntu1
+   Version table:
+  *** 1:2.27.1-4ubuntu1 500
+         500 http://archive.ubuntu.com/ubuntu xenial-proposed/main amd64 Packages
+         100 /var/lib/dpkg/status
+      1:2.27.1-3ubuntu1 500
+         500 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages
  coreutils:
-   Installed: 8.25-2ubuntu2
-   Candidate: 8.25-2ubuntu2
-   Version table:
-  *** 8.25-2ubuntu2 500
-         500 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages
-         100 /var/lib/dpkg/status
+   Installed: 8.25-2ubuntu2
+   Candidate: 8.25-2ubuntu2
+   Version table:
+  *** 8.25-2ubuntu2 500
+         500 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages
+         100 /var/lib/dpkg/status
  
  ProblemType: Bug
  DistroRelease: Ubuntu 16.04
  Package: util-linux 2.27.1-4ubuntu1
  ProcVersionSignature: Ubuntu 4.4.0-10.25-generic 4.4.3
  Uname: Linux 4.4.0-10-generic x86_64
  NonfreeKernelModules: zfs zunicode zcommon znvpair zavl
  ApportVersion: 2.20-0ubuntu3
  Architecture: amd64
  CurrentDesktop: Unity
  Date: Fri Mar  4 15:14:15 2016
  SourcePackage: util-linux
  UpgradeStatus: No upgrade log present (probably fresh install)

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to util-linux in Ubuntu.
https://bugs.launchpad.net/bugs/1553353

Title:
  tail'ing a file in a script session hangs

Status in util-linux package in Ubuntu:
  Confirmed
Status in util-linux source package in Xenial:
  Confirmed

Bug description:
  Steps to reproduce:

  1) Start script session (same issue when script is saving to /dev/null)
  script # or: script /dev/null
  2) Tail a file
  tailf /var/log/syslog
  3) Press "Enter" 2 times
  4) Notice the script process taking 100% CPU

  This regression was introduced upstream by this commit:
  https://git.kernel.org/cgit/utils/util-linux/util-
  linux.git/commit/?id=54c6611d6f7b73609a5331f4d0bcf63c4af6429e

  $ lsb_release -rd
  Description:	Ubuntu Xenial Xerus (development branch)
  Release:	16.04

  $ apt-cache policy util-linux bsdutils coreutils
  util-linux:
    Installed: 2.27.1-4ubuntu1
    Candidate: 2.27.1-4ubuntu1
    Version table:
   *** 2.27.1-4ubuntu1 500
          500 http://archive.ubuntu.com/ubuntu xenial-proposed/main amd64 Packages
          100 /var/lib/dpkg/status
       2.27.1-3ubuntu1 500
          500 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages
  bsdutils:
    Installed: 1:2.27.1-4ubuntu1
    Candidate: 1:2.27.1-4ubuntu1
    Version table:
   *** 1:2.27.1-4ubuntu1 500
          500 http://archive.ubuntu.com/ubuntu xenial-proposed/main amd64 Packages
          100 /var/lib/dpkg/status
       1:2.27.1-3ubuntu1 500
          500 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages
  coreutils:
    Installed: 8.25-2ubuntu2
    Candidate: 8.25-2ubuntu2
    Version table:
   *** 8.25-2ubuntu2 500
          500 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages
          100 /var/lib/dpkg/status

  ProblemType: Bug
  DistroRelease: Ubuntu 16.04
  Package: util-linux 2.27.1-4ubuntu1
  ProcVersionSignature: Ubuntu 4.4.0-10.25-generic 4.4.3
  Uname: Linux 4.4.0-10-generic x86_64
  NonfreeKernelModules: zfs zunicode zcommon znvpair zavl
  ApportVersion: 2.20-0ubuntu3
  Architecture: amd64
  CurrentDesktop: Unity
  Date: Fri Mar  4 15:14:15 2016
  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/1553353/+subscriptions