>From the above comments I think it's clear that the problem is caused by some kind of misconfiguration resulting in a loop. It isn't clear if that misconfiguration is coming from a user error or from some bug in an upgrade path somewhere. If the latter, then it's a valid bug. However, since we don't have steps to reproduce the problem, I'm marking this bug as Incomplete in dnsmasq, to make it clear that developers aren't expected to be able to make any progress on this problem until someone can provide steps to reproduce.
** Changed in: dnsmasq (Ubuntu) Status: Confirmed => Incomplete ** Description changed: + [Triage Notes] + "Incomplete" in dnsmasq: may be a valid bug, but developers cannot make progress until someone can provide steps to reproduce. See comment 55. + + [Original 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 -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to dnsmasq in Ubuntu. https://bugs.launchpad.net/bugs/1670959 Title: systemd-resolved using 100% CPU Status in dnsmasq package in Ubuntu: Incomplete Status in systemd package in Ubuntu: Confirmed Bug description: [Triage Notes] "Incomplete" in dnsmasq: may be a valid bug, but developers cannot make progress until someone can provide steps to reproduce. See comment 55. [Original 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 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/dnsmasq/+bug/1670959/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp