[Touch-packages] [Bug 1535840] Re: systemd ignoring /etc/modules due to blacklist

2023-05-19 Thread James Cuzella
** Also affects: linux (Ubuntu)
   Importance: Undecided
   Status: New

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Title:
  systemd ignoring /etc/modules due to blacklist

Status in linux package in Ubuntu:
  New
Status in systemd package in Ubuntu:
  Opinion

Bug description:
  I tried the daily build of 16.04 32-bit to test out the watchdog
  daemon code. Usually (Ubuntu 10.04-14.04) I add the watchdog module in
  /etc/modules so it is loaded at boot-time, as watchdog timer modules
  are not normally auto-loaded due to the risk of an unexpected reboot.

  However I now find that systemd is choosing to ignore my command to
  load the module in /etc/modules since it appears in the watchdog
  blacklist. Typical syslog entries look like this:

  Jan 19 16:46:14 ubuntu systemd-modules-load[337]: Module 'softdog' is 
blacklisted
  Jan 19 17:53:23 ubuntu systemd-modules-load[342]: Module 'softdog' is 
blacklisted

  This is just dumb! I have explicitly told the system to load the
  module, an action that works perfectly well using modprobe or by
  adding it to the start script for the watchdog, and yet systemd
  chooses to override that because of the blacklist for auto-loaded
  modules (in this case in /etc/modprobe.d/blacklist-watchdog.conf).

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

  $ apt-cache policy systemd
  systemd:
Installed: 228-4ubuntu1
Candidate: 228-4ubuntu1
Version table:
   *** 228-4ubuntu1 500
  500 http://us.archive.ubuntu.com/ubuntu xenial/main i386 Packages
  100 /var/lib/dpkg/status

  What I expect to happen is modules added to /etc/modules are loaded at
  boot time, and not subject to the blacklist for hardware detect /
  automatic loading.

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[Touch-packages] [Bug 1535840] Re: systemd ignoring /etc/modules due to blacklist

2023-05-19 Thread James Cuzella
Confirmed this still exists in 22.04 (Jammy Jellyfish), with symptoms
being SystemD booting always into "degraded" state because wdmd.service
(Watchdog Multiplexing Daemon) will always fail due to missing watchdog
kernel module(s).

Check this is the case with:

sudo systemctl status
sudo systemctl list-units --failed 

The solution suggested by @ishworgurung works to allow iTCO_wdt (and other 
watchdogs) to be loaded by the kernel during boot appropriately.  Then, 
wdmd.service starts up successfully and SystemD enters successful "running" 
state (assuming all other SystemD services are working properly).
However, every kernel package update will place another blacklist file in 
/lib/modprobe.d/blacklist_linux_$(uname -r).conf.  So this is only a temporary 
workaround until these modules are not blacklisted by default.

The blacklist files are part of linux-modules-$(uname -r) package(s).
Therefore, this bug should be listed as also affecting Linux kernel
source packages for Ubuntu.

$ dpkg -S /lib/modprobe.d/blacklist_linux_*.conf
linux-modules-5.15.0-74-generic: 
/lib/modprobe.d/blacklist_linux_5.15.0-74-generic.conf
linux-modules-5.4.0-149-generic: 
/lib/modprobe.d/blacklist_linux_5.4.0-149-generic.conf
# ^^ These packages own /lib/modprobe.d/blacklist_linux*.conf files

$ apt-cache show linux-modules-$(uname -r) | grep -C5 Source: | sed -e 
's/^//'
Package: linux-modules-5.15.0-74-generic
Architecture: amd64
Version: 5.15.0-74.81
Priority: optional
Section: kernel
Source: linux
Origin: Ubuntu
Maintainer: Ubuntu Kernel Team 
Bugs: https://bugs.launchpad.net/ubuntu/+filebug
Installed-Size: 123864
Depends: linux-image-5.15.0-74-generic | 
linux-image-unsigned-5.15.0-74-generic
## ^^ Part of Linux APT package(s) in Ubuntu

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https://bugs.launchpad.net/bugs/1535840

Title:
  systemd ignoring /etc/modules due to blacklist

Status in systemd package in Ubuntu:
  Opinion

Bug description:
  I tried the daily build of 16.04 32-bit to test out the watchdog
  daemon code. Usually (Ubuntu 10.04-14.04) I add the watchdog module in
  /etc/modules so it is loaded at boot-time, as watchdog timer modules
  are not normally auto-loaded due to the risk of an unexpected reboot.

  However I now find that systemd is choosing to ignore my command to
  load the module in /etc/modules since it appears in the watchdog
  blacklist. Typical syslog entries look like this:

  Jan 19 16:46:14 ubuntu systemd-modules-load[337]: Module 'softdog' is 
blacklisted
  Jan 19 17:53:23 ubuntu systemd-modules-load[342]: Module 'softdog' is 
blacklisted

  This is just dumb! I have explicitly told the system to load the
  module, an action that works perfectly well using modprobe or by
  adding it to the start script for the watchdog, and yet systemd
  chooses to override that because of the blacklist for auto-loaded
  modules (in this case in /etc/modprobe.d/blacklist-watchdog.conf).

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

  $ apt-cache policy systemd
  systemd:
Installed: 228-4ubuntu1
Candidate: 228-4ubuntu1
Version table:
   *** 228-4ubuntu1 500
  500 http://us.archive.ubuntu.com/ubuntu xenial/main i386 Packages
  100 /var/lib/dpkg/status

  What I expect to happen is modules added to /etc/modules are loaded at
  boot time, and not subject to the blacklist for hardware detect /
  automatic loading.

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[Touch-packages] [Bug 1670959] Re: systemd-resolved using 100% CPU

2017-11-28 Thread James Cuzella
Maybe interesting things to note:

1. When in bad state:
  - The mentioned ENV var change in /etc/default/dnsmasq and `sudo systemctl 
restart dnsmasq` immediately resolves the issue
2. When in good state:
  - Commenting out the ENV var and running `sudo systemctl restart dnsmasq` 
does not immediately re-cause the issue
  - After a reboot, the bad state can be observed again (systemd-resolved using 
100% of a CPU core)

Maybe there is an order of operations thing here?

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https://bugs.launchpad.net/bugs/1670959

Title:
  systemd-resolved using 100% CPU

Status in dnsmasq package in Ubuntu:
  Confirmed
Status in systemd package in Ubuntu:
  Confirmed

Bug description:
  Sometimes systemd-resolved process is using 100% CPU.
  After a while it changes back to normal.

  It happens usually after connecting to the (wifi) network, like
  starting the OS.

  strace output:

  sendmsg(12, {msg_name(16)={sa_family=AF_INET, sin_port=htons(33589), 
sin_addr=inet_addr("127.0.0.1")}, 
msg_iov(1)=[{"6\215\201\200\0\1\0\1\0\0\0\1\4cs41\3wac\vedgecastcdn\3net\0\0\34\0\1\300\f\0\34\0\1\0\0\10\235\0\20&\6(\0\0024\0Y%L\4\6#f&\214\0\0)\377\326\0\0\0\0\0\0",
 81}], msg_controllen=28, [{cmsg_len=28, cmsg_level=SOL_IP, 
cmsg_type=IP_PKTINFO, {ipi_ifindex=if_nametoindex("lo"), 
ipi_spec_dst=inet_addr("127.0.0.53"), ipi_addr=inet_addr("127.0.0.53")}}], 
msg_flags=0}, 0) = 81
  sendmsg(3, {msg_name(0)=NULL, 
msg_iov(4)=[{"PRIORITY=6\nSYSLOG_FACILITY=3\nCODE_FILE=../src/resolve/resolved-dns-stub.c\nCODE_LINE=363\nCODE_FUNCTION=dns_stub_process_query\nSYSLOG_IDENTIFIER=systemd-resolved\n",
 160}, {"MESSAGE=", 8}, {"Processing query...", 19}, {"\n", 1}], 
msg_controllen=0, msg_flags=0}, MSG_NOSIGNAL) = 188
  epoll_wait(4, [{EPOLLIN, {u32=3176459184, u64=94565471415216}}], 16, -1) = 1
  clock_gettime(CLOCK_BOOTTIME, {44665, 938069872}) = 0
  recvfrom(12, NULL, 0, MSG_PEEK|MSG_TRUNC, NULL, NULL) = 53
  recvmsg(12, {msg_name(16)={sa_family=AF_INET, sin_port=htons(33589), 
sin_addr=inet_addr("127.0.0.1")}, 
msg_iov(1)=[{"Z\262\1\20\0\1\0\0\0\0\0\1\4cs41\3wac\vedgecastcdn\3net\0\0\34\0\1\0\0)\2\0\0\0\0\0\0\0",
 3936}], msg_controllen=56, [{cmsg_len=28, cmsg_level=SOL_IP, 
cmsg_type=IP_PKTINFO, {ipi_ifindex=if_nametoindex("lo"), 
ipi_spec_dst=inet_addr("127.0.0.53"), ipi_addr=inet_addr("127.0.0.53")}}, 
{cmsg_len=20, cmsg_level=SOL_IP, cmsg_type=IP_TTL, {ttl=64}}], msg_flags=0}, 0) 
= 53
  stat("/etc/resolv.conf", {st_mode=S_IFREG|0644, st_size=303, ...}) = 0
  getrandom("\365I", 2, GRND_NONBLOCK)= 2
  stat("/etc/resolv.conf", {st_mode=S_IFREG|0644, st_size=303, ...}) = 0
  getrandom("\203;", 2, GRND_NONBLOCK)= 2
  clock_gettime(CLOCK_BOOTTIME, {44665, 938446937}) = 0
  open("/run/systemd/netif/links/3", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such 
file or directory)
  stat("/etc/resolv.conf", {st_mode=S_IFREG|0644, st_size=303, ...}) = 0
  stat("/etc/resolv.conf", {st_mode=S_IFREG|0644, st_size=303, ...}) = 0
  socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, IPPROTO_IP) = 18
  connect(18, {sa_family=AF_INET, sin_port=htons(53), 
sin_addr=inet_addr("127.0.0.1")}, 16) = 0
  epoll_ctl(4, EPOLL_CTL_ADD, 18, {EPOLLIN, {u32=3176610576, 
u64=94565471566608}}) = 0
  write(18, 
"\203;\1\20\0\1\0\0\0\0\0\1\4cs41\3wac\vedgecastcdn\3net\0\0\34\0\1\0\0)\2\0\0\0\0\0\0\0",
 53) = 53
  clock_gettime(CLOCK_BOOTTIME, {44665, 938833717}) = 0
  clock_gettime(CLOCK_BOOTTIME, {44665, 938875138}) = 0
  epoll_ctl(4, EPOLL_CTL_DEL, 18, NULL)   = 0
  close(18)   = 0

  journalctl output:

  Mar 08 08:25:35 parsec systemd-resolved[1512]: Processing query...
  Mar 08 08:25:35 parsec systemd-resolved[1512]: Processing query...
  Mar 08 08:25:35 parsec systemd-resolved[1512]: Processing query...
  Mar 08 08:25:35 parsec systemd-resolved[1512]: Processing query...
  Mar 08 08:25:35 parsec systemd-resolved[1512]: Processing query...
  Mar 08 08:25:35 parsec systemd-resolved[1512]: Processing query...
  Mar 08 08:25:35 parsec systemd-resolved[1512]: Processing query...
  Mar 08 08:25:35 parsec systemd-resolved[1512]: Processing query...
  Mar 08 08:25:41 parsec dnsmasq[1545]: Maximum number of concurrent DNS 
queries reached (max: 150)

  As you can see, I would use it together with dnsmasq.

  ProblemType: Bug
  DistroRelease: Ubuntu 17.04
  Package: systemd 232-18ubuntu1
  ProcVersionSignature: Ubuntu 4.10.0-9.11-generic 4.10.0
  Uname: Linux 4.10.0-9-generic x86_64
  NonfreeKernelModules: zfs zunicode zavl zcommon znvpair
  ApportVersion: 2.20.4-0ubuntu2
  Architecture: amd64
  Date: Wed Mar  8 08:20:18 2017
  MachineType: Hewlett-Packard HP EliteBook Folio 1020 G1
  ProcEnviron:
   LANGUAGE=en_US:en
   TERM=xterm
   PATH=(custom, no user)
   LANG=en_US.UTF-8
   SHELL=/bin/zsh
  ProcKernelCmdLine: BOOT_IMAGE=/@/boot/vmlinuz-4.10.0-9-generic 
root=UUID=a54fe703-35d4-47ac-9c6e-4034421531fb ro 

[Touch-packages] [Bug 1670959] Re: systemd-resolved using 100% CPU

2017-11-28 Thread James Cuzella
Christian: I've tried as I believe you have asked.

When in the bad case (I comment out the line: DNSMASQ_EXCEPT=lo and then
reboot):

 - Running this did not resolve the issue: `sudo resolvconf -a lo.dnsmasq`
 - Running this did not resolve the issue: `echo "nameserver 127.0.0.1" | 
/sbin/resolvconf -a lo.dnsmasq`

So far only the DNSMASQ_EXCEPT=lo line in /etc/default/dnsmasq appears
to resolve the issue.

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https://bugs.launchpad.net/bugs/1670959

Title:
  systemd-resolved using 100% CPU

Status in dnsmasq package in Ubuntu:
  Confirmed
Status in systemd package in Ubuntu:
  Confirmed

Bug description:
  Sometimes systemd-resolved process is using 100% CPU.
  After a while it changes back to normal.

  It happens usually after connecting to the (wifi) network, like
  starting the OS.

  strace output:

  sendmsg(12, {msg_name(16)={sa_family=AF_INET, sin_port=htons(33589), 
sin_addr=inet_addr("127.0.0.1")}, 
msg_iov(1)=[{"6\215\201\200\0\1\0\1\0\0\0\1\4cs41\3wac\vedgecastcdn\3net\0\0\34\0\1\300\f\0\34\0\1\0\0\10\235\0\20&\6(\0\0024\0Y%L\4\6#f&\214\0\0)\377\326\0\0\0\0\0\0",
 81}], msg_controllen=28, [{cmsg_len=28, cmsg_level=SOL_IP, 
cmsg_type=IP_PKTINFO, {ipi_ifindex=if_nametoindex("lo"), 
ipi_spec_dst=inet_addr("127.0.0.53"), ipi_addr=inet_addr("127.0.0.53")}}], 
msg_flags=0}, 0) = 81
  sendmsg(3, {msg_name(0)=NULL, 
msg_iov(4)=[{"PRIORITY=6\nSYSLOG_FACILITY=3\nCODE_FILE=../src/resolve/resolved-dns-stub.c\nCODE_LINE=363\nCODE_FUNCTION=dns_stub_process_query\nSYSLOG_IDENTIFIER=systemd-resolved\n",
 160}, {"MESSAGE=", 8}, {"Processing query...", 19}, {"\n", 1}], 
msg_controllen=0, msg_flags=0}, MSG_NOSIGNAL) = 188
  epoll_wait(4, [{EPOLLIN, {u32=3176459184, u64=94565471415216}}], 16, -1) = 1
  clock_gettime(CLOCK_BOOTTIME, {44665, 938069872}) = 0
  recvfrom(12, NULL, 0, MSG_PEEK|MSG_TRUNC, NULL, NULL) = 53
  recvmsg(12, {msg_name(16)={sa_family=AF_INET, sin_port=htons(33589), 
sin_addr=inet_addr("127.0.0.1")}, 
msg_iov(1)=[{"Z\262\1\20\0\1\0\0\0\0\0\1\4cs41\3wac\vedgecastcdn\3net\0\0\34\0\1\0\0)\2\0\0\0\0\0\0\0",
 3936}], msg_controllen=56, [{cmsg_len=28, cmsg_level=SOL_IP, 
cmsg_type=IP_PKTINFO, {ipi_ifindex=if_nametoindex("lo"), 
ipi_spec_dst=inet_addr("127.0.0.53"), ipi_addr=inet_addr("127.0.0.53")}}, 
{cmsg_len=20, cmsg_level=SOL_IP, cmsg_type=IP_TTL, {ttl=64}}], msg_flags=0}, 0) 
= 53
  stat("/etc/resolv.conf", {st_mode=S_IFREG|0644, st_size=303, ...}) = 0
  getrandom("\365I", 2, GRND_NONBLOCK)= 2
  stat("/etc/resolv.conf", {st_mode=S_IFREG|0644, st_size=303, ...}) = 0
  getrandom("\203;", 2, GRND_NONBLOCK)= 2
  clock_gettime(CLOCK_BOOTTIME, {44665, 938446937}) = 0
  open("/run/systemd/netif/links/3", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such 
file or directory)
  stat("/etc/resolv.conf", {st_mode=S_IFREG|0644, st_size=303, ...}) = 0
  stat("/etc/resolv.conf", {st_mode=S_IFREG|0644, st_size=303, ...}) = 0
  socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, IPPROTO_IP) = 18
  connect(18, {sa_family=AF_INET, sin_port=htons(53), 
sin_addr=inet_addr("127.0.0.1")}, 16) = 0
  epoll_ctl(4, EPOLL_CTL_ADD, 18, {EPOLLIN, {u32=3176610576, 
u64=94565471566608}}) = 0
  write(18, 
"\203;\1\20\0\1\0\0\0\0\0\1\4cs41\3wac\vedgecastcdn\3net\0\0\34\0\1\0\0)\2\0\0\0\0\0\0\0",
 53) = 53
  clock_gettime(CLOCK_BOOTTIME, {44665, 938833717}) = 0
  clock_gettime(CLOCK_BOOTTIME, {44665, 938875138}) = 0
  epoll_ctl(4, EPOLL_CTL_DEL, 18, NULL)   = 0
  close(18)   = 0

  journalctl output:

  Mar 08 08:25:35 parsec systemd-resolved[1512]: Processing query...
  Mar 08 08:25:35 parsec systemd-resolved[1512]: Processing query...
  Mar 08 08:25:35 parsec systemd-resolved[1512]: Processing query...
  Mar 08 08:25:35 parsec systemd-resolved[1512]: Processing query...
  Mar 08 08:25:35 parsec systemd-resolved[1512]: Processing query...
  Mar 08 08:25:35 parsec systemd-resolved[1512]: Processing query...
  Mar 08 08:25:35 parsec systemd-resolved[1512]: Processing query...
  Mar 08 08:25:35 parsec systemd-resolved[1512]: Processing query...
  Mar 08 08:25:41 parsec dnsmasq[1545]: Maximum number of concurrent DNS 
queries reached (max: 150)

  As you can see, I would use it together with dnsmasq.

  ProblemType: Bug
  DistroRelease: Ubuntu 17.04
  Package: systemd 232-18ubuntu1
  ProcVersionSignature: Ubuntu 4.10.0-9.11-generic 4.10.0
  Uname: Linux 4.10.0-9-generic x86_64
  NonfreeKernelModules: zfs zunicode zavl zcommon znvpair
  ApportVersion: 2.20.4-0ubuntu2
  Architecture: amd64
  Date: Wed Mar  8 08:20:18 2017
  MachineType: Hewlett-Packard HP EliteBook Folio 1020 G1
  ProcEnviron:
   LANGUAGE=en_US:en
   TERM=xterm
   PATH=(custom, no user)
   LANG=en_US.UTF-8
   SHELL=/bin/zsh
  ProcKernelCmdLine: BOOT_IMAGE=/@/boot/vmlinuz-4.10.0-9-generic 
root=UUID=a54fe703-35d4-47ac-9c6e-4034421531fb ro rootflags=subvol=@
  SourcePackage: systemd
  UpgradeStatus: 

[Touch-packages] [Bug 1670959] Re: systemd-resolved using 100% CPU

2017-11-08 Thread James Cuzella
Also seeing this issue in Ubuntu 17.10 (artful) with:

dnsmasq-base  2.78-1
systemd   234-2ubuntu12.1

I can confirm that following https://askubuntu.com/a/968309/  resolves
the issue!

Steps to fix the issue:

Added this line to /etc/default/dnsmasq:

DNSMASQ_EXCEPT=lo

Then restarting dnsmasq:

sudo systemctl daemon-reload
sudo systemctl restart dnsmasq

No more systemd-resolved taking 99-100% of a CPU core!

-- 
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https://bugs.launchpad.net/bugs/1670959

Title:
  systemd-resolved using 100% CPU

Status in dnsmasq package in Ubuntu:
  Confirmed
Status in systemd package in Ubuntu:
  Confirmed

Bug description:
  Sometimes systemd-resolved process is using 100% CPU.
  After a while it changes back to normal.

  It happens usually after connecting to the (wifi) network, like
  starting the OS.

  strace output:

  sendmsg(12, {msg_name(16)={sa_family=AF_INET, sin_port=htons(33589), 
sin_addr=inet_addr("127.0.0.1")}, 
msg_iov(1)=[{"6\215\201\200\0\1\0\1\0\0\0\1\4cs41\3wac\vedgecastcdn\3net\0\0\34\0\1\300\f\0\34\0\1\0\0\10\235\0\20&\6(\0\0024\0Y%L\4\6#f&\214\0\0)\377\326\0\0\0\0\0\0",
 81}], msg_controllen=28, [{cmsg_len=28, cmsg_level=SOL_IP, 
cmsg_type=IP_PKTINFO, {ipi_ifindex=if_nametoindex("lo"), 
ipi_spec_dst=inet_addr("127.0.0.53"), ipi_addr=inet_addr("127.0.0.53")}}], 
msg_flags=0}, 0) = 81
  sendmsg(3, {msg_name(0)=NULL, 
msg_iov(4)=[{"PRIORITY=6\nSYSLOG_FACILITY=3\nCODE_FILE=../src/resolve/resolved-dns-stub.c\nCODE_LINE=363\nCODE_FUNCTION=dns_stub_process_query\nSYSLOG_IDENTIFIER=systemd-resolved\n",
 160}, {"MESSAGE=", 8}, {"Processing query...", 19}, {"\n", 1}], 
msg_controllen=0, msg_flags=0}, MSG_NOSIGNAL) = 188
  epoll_wait(4, [{EPOLLIN, {u32=3176459184, u64=94565471415216}}], 16, -1) = 1
  clock_gettime(CLOCK_BOOTTIME, {44665, 938069872}) = 0
  recvfrom(12, NULL, 0, MSG_PEEK|MSG_TRUNC, NULL, NULL) = 53
  recvmsg(12, {msg_name(16)={sa_family=AF_INET, sin_port=htons(33589), 
sin_addr=inet_addr("127.0.0.1")}, 
msg_iov(1)=[{"Z\262\1\20\0\1\0\0\0\0\0\1\4cs41\3wac\vedgecastcdn\3net\0\0\34\0\1\0\0)\2\0\0\0\0\0\0\0",
 3936}], msg_controllen=56, [{cmsg_len=28, cmsg_level=SOL_IP, 
cmsg_type=IP_PKTINFO, {ipi_ifindex=if_nametoindex("lo"), 
ipi_spec_dst=inet_addr("127.0.0.53"), ipi_addr=inet_addr("127.0.0.53")}}, 
{cmsg_len=20, cmsg_level=SOL_IP, cmsg_type=IP_TTL, {ttl=64}}], msg_flags=0}, 0) 
= 53
  stat("/etc/resolv.conf", {st_mode=S_IFREG|0644, st_size=303, ...}) = 0
  getrandom("\365I", 2, GRND_NONBLOCK)= 2
  stat("/etc/resolv.conf", {st_mode=S_IFREG|0644, st_size=303, ...}) = 0
  getrandom("\203;", 2, GRND_NONBLOCK)= 2
  clock_gettime(CLOCK_BOOTTIME, {44665, 938446937}) = 0
  open("/run/systemd/netif/links/3", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such 
file or directory)
  stat("/etc/resolv.conf", {st_mode=S_IFREG|0644, st_size=303, ...}) = 0
  stat("/etc/resolv.conf", {st_mode=S_IFREG|0644, st_size=303, ...}) = 0
  socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, IPPROTO_IP) = 18
  connect(18, {sa_family=AF_INET, sin_port=htons(53), 
sin_addr=inet_addr("127.0.0.1")}, 16) = 0
  epoll_ctl(4, EPOLL_CTL_ADD, 18, {EPOLLIN, {u32=3176610576, 
u64=94565471566608}}) = 0
  write(18, 
"\203;\1\20\0\1\0\0\0\0\0\1\4cs41\3wac\vedgecastcdn\3net\0\0\34\0\1\0\0)\2\0\0\0\0\0\0\0",
 53) = 53
  clock_gettime(CLOCK_BOOTTIME, {44665, 938833717}) = 0
  clock_gettime(CLOCK_BOOTTIME, {44665, 938875138}) = 0
  epoll_ctl(4, EPOLL_CTL_DEL, 18, NULL)   = 0
  close(18)   = 0

  journalctl output:

  Mar 08 08:25:35 parsec systemd-resolved[1512]: Processing query...
  Mar 08 08:25:35 parsec systemd-resolved[1512]: Processing query...
  Mar 08 08:25:35 parsec systemd-resolved[1512]: Processing query...
  Mar 08 08:25:35 parsec systemd-resolved[1512]: Processing query...
  Mar 08 08:25:35 parsec systemd-resolved[1512]: Processing query...
  Mar 08 08:25:35 parsec systemd-resolved[1512]: Processing query...
  Mar 08 08:25:35 parsec systemd-resolved[1512]: Processing query...
  Mar 08 08:25:35 parsec systemd-resolved[1512]: Processing query...
  Mar 08 08:25:41 parsec dnsmasq[1545]: Maximum number of concurrent DNS 
queries reached (max: 150)

  As you can see, I would use it together with dnsmasq.

  ProblemType: Bug
  DistroRelease: Ubuntu 17.04
  Package: systemd 232-18ubuntu1
  ProcVersionSignature: Ubuntu 4.10.0-9.11-generic 4.10.0
  Uname: Linux 4.10.0-9-generic x86_64
  NonfreeKernelModules: zfs zunicode zavl zcommon znvpair
  ApportVersion: 2.20.4-0ubuntu2
  Architecture: amd64
  Date: Wed Mar  8 08:20:18 2017
  MachineType: Hewlett-Packard HP EliteBook Folio 1020 G1
  ProcEnviron:
   LANGUAGE=en_US:en
   TERM=xterm
   PATH=(custom, no user)
   LANG=en_US.UTF-8
   SHELL=/bin/zsh
  ProcKernelCmdLine: BOOT_IMAGE=/@/boot/vmlinuz-4.10.0-9-generic 
root=UUID=a54fe703-35d4-47ac-9c6e-4034421531fb ro rootflags=subvol=@
  SourcePackage: systemd