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

Tue Jul 31 21:44:02 UTC 2018

I also think it's an upgrade artifact. It happened on my upgraded laptop but not in the freshly installed desktop machine. 
The problem in the laptop now (I think) hostapd that requires dnsmasq. 
The workaround cited by @ahasenack in #49 seems to work.

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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: 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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