Interesting James,
so there is a little twist that might be related and lead to a resolution.
Usually the service of dnsmasq would add itself to the resolvconf server set.
It does so in:
start_resolvconf()
{
# If interface "lo" is explicitly disabled in /etc/default/dnsmasq
# Then dnsmasq won't be providing local DNS, so don't add it to
# the resolvconf server set.
for interface in $DNSMASQ_EXCEPT
do
[ $interface = lo ] && return
done
# Also skip this if DNS functionality is disabled in /etc/dnsmasq.conf
if grep -qs '^port=0' /etc/dnsmasq.conf; then
return
fi
if [ -x /sbin/resolvconf ] ; then
echo "nameserver 127.0.0.1" | /sbin/resolvconf -a lo.$NAME
fi
return 0
}
So I wonder if that "not adding to resolvconf is the actual way this is
fixed for you per https://askubuntu.com/a/968309/
So while the config says "do not server lo", what it really does to fix
your case is not adding it. That in turn one could test.
So once you are in the bad case could you try if
$ resolvconf -a lo.dnsmasq
would resolv the issue as well?
I currently fail to grasp all the potential regressions that change could have,
but I'd think that knowing if
a) not serving on 127.0.0.1
or
b) not registering in resolvconf
is the actual trigger might help someone else to go further.
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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: 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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