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

Thu Apr 20 02:06:16 UTC 2017

> This is a good workaround, but perhaps the actual fix should be to
remove the package on upgrade to 17.04?

What do you mean by this?
The fix should not ever something like this.
There is reason why dnsmasq is installed on these machines.

This is a workaround by not good.

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Title:
  systemd-resolved using 100% CPU

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: Upgraded to zesty on 2015-05-24 (653 days ago)
  dmi.bios.date: 03/09/2015
  dmi.bios.vendor: Hewlett-Packard
  dmi.bios.version: M77 Ver. 01.05
  dmi.board.name: 2271
  dmi.board.vendor: Hewlett-Packard
  dmi.board.version: KBC Version 91.4C
  dmi.chassis.asset.tag: CNU51199KV
  dmi.chassis.type: 10
  dmi.chassis.vendor: Hewlett-Packard
  dmi.modalias: dmi:bvnHewlett-Packard:bvrM77Ver.01.05:bd03/09/2015:svnHewlett-Packard:pnHPEliteBookFolio1020G1:pvrA3009DD18303:rvnHewlett-Packard:rn2271:rvrKBCVersion91.4C:cvnHewlett-Packard:ct10:cvr:
  dmi.product.name: HP EliteBook Folio 1020 G1
  dmi.product.version: A3009DD18303
  dmi.sys.vendor: Hewlett-Packard

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