gdm uses 100% cpu on aarch64 (fedora 33)
I'm observing that gdm uses 100% cpu on aarch64 architecture.
Tasks: 230 total, 2 running, 228 sleeping, 0 stopped, 0 zombie
%Cpu0 : 1.2 us, 1.2 sy, 0.0 ni, 97.6 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
%Cpu1 : 1.2 us, 0.0 sy, 0.0 ni, 98.8 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
%Cpu2 : 73.5 us, 26.5 sy, 0.0 ni, 0.0 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
%Cpu3 : 0.0 us, 0.0 sy, 0.0 ni,100.0 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
MiB Mem : 3792.1 total, 1128.8 free, 832.5 used, 1830.8 buff/cache
MiB Swap: 1896.0 total, 1896.0 free, 0.0 used. 2745.1 avail Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
466 root 20 0 470044 8396 7336 R 100.0 0.2 247:11.42 gdm
3501 dw 20 0 236072 4268 3620 R 3.7 0.1 0:00.07 top
1 root 20 0 173528 12824 9476 S 0.0 0.3 0:05.95 systemd
2 root 20 0 0 0 0 S 0.0 0.0 0:00.03 kthreadd
3 root 0 -20 0 0 0 I 0.0 0.0 0:00.00 rcu_gp
4 root 0 -20 0 0 0 I 0.0 0.0 0:00.00 rcu_par_gp
6 root 0 -20 0 0 0 I 0.0 0.0 0:00.00 kworker/0:0H-kblockd $ sudo strace -p 466
strace: Process 466 attached
ppoll([{fd=7, events=POLLIN}, {fd=10, events=POLLPRI}, {fd=11, events=POLLIN}, {fd=12, events=POLLIN}, {fd=18, events=POLLIN}, {fd=19, events=POLLIN}], 6, {tv_sec=0, tv_nsec=0}, NULL, 0) = 0 (Timeout)
ppoll([{fd=7, events=POLLIN}, {fd=10, events=POLLPRI}, {fd=11, events=POLLIN}, {fd=12, events=POLLIN}, {fd=18, events=POLLIN}, {fd=19, events=POLLIN}], 6, {tv_sec=0, tv_nsec=0}, NULL, 0) = 0 (Timeout)
ppoll([{fd=7, events=POLLIN}, {fd=10, events=POLLPRI}, {fd=11, events=POLLIN}, {fd=12, events=POLLIN}, {fd=18, events=POLLIN}, {fd=19, events=POLLIN}], 6, {tv_sec=0, tv_nsec=0}, NULL, 0) = 0 (Timeout)
ppoll([{fd=7, events=POLLIN}, {fd=10, events=POLLPRI}, {fd=11, events=POLLIN}, {fd=12, events=POLLIN}, {fd=18, events=POLLIN}, {fd=19, events=POLLIN}], 6, {tv_sec=0, tv_nsec=0}, NULL, 0) = 0 (Timeout)
ppoll([{fd=7, events=POLLIN}, {fd=10, events=POLLPRI}, {fd=11, events=POLLIN}, {fd=12, events=POLLIN}, {fd=18, events=POLLIN}, {fd=19, events=POLLIN}], 6, {tv_sec=0, tv_nsec=0}, NULL, 0) = 0 (Timeout)
ppoll([{fd=7, events=POLLIN}, {fd=10, events=POLLPRI}, {fd=11, events=POLLIN}, {fd=12, events=POLLIN}, {fd=18, events=POLLIN}, {fd=19, events=POLLIN}], 6, {tv_sec=0, tv_nsec=0}, NULL, 0) = 0 (Timeout)
ppoll([{fd=7, events=POLLIN}, {fd=10, events=POLLPRI}, {fd=11, events=POLLIN}, {fd=12, events=POLLIN}, {fd=18, events=POLLIN}, {fd=19, events=POLLIN}], 6, {tv_sec=0, tv_nsec=0}, NULL, 0) = 0 (Timeout)
ppoll([{fd=7, events=POLLIN}, {fd=10, events=POLLPRI}, {fd=11, events=POLLIN}, {fd=12, events=POLLIN}, {fd=18, events=POLLIN}, {fd=19, events=POLLIN}], 6, {tv_sec=0, tv_nsec=0}, NULL, 0) = 0 (Timeout)
ppoll([{fd=7, events=POLLIN}, {fd=10, events=POLLPRI}, {fd=11, events=POLLIN}, {fd=12, events=POLLIN}, {fd=18, events=POLLIN}, {fd=19, events=POLLIN}], 6, {tv_sec=0, tv_nsec=0}, NULL, 0) = 0 (Timeout)
ppoll([{fd=7, events=POLLIN}, {fd=10, events=POLLPRI}, {fd=11, events=POLLIN}, {fd=12, events=POLLIN}, {fd=18, events=POLLIN}, {fd=19, events=POLLIN}], 6, {tv_sec=0, tv_nsec=0}, NULL, 0) = 0 (Timeout)
ppoll([{fd=7, events=POLLIN}, {fd=10, events=POLLPRI}, {fd=11, events=POLLIN}, {fd=12, events=POLLIN}, {fd=18, events=POLLIN}, {fd=19, events=POLLIN}], 6, {tv_sec=0, tv_nsec=0}, NULL, 0) = 0 (Timeout)
ppoll([{fd=7, events=POLLIN}, {fd=10, events=POLLPRI}, {fd=11, events=POLLIN}, {fd=12, events=POLLIN}, {fd=18, events=POLLIN}, {fd=19, events=POLLIN}], 6, {tv_sec=0, tv_nsec=0}, NULL, 0) = 0 (Timeout)$ sudo gdb -p 466
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Attaching to process 466
[New LWP 468]
[New LWP 469]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
0x0000007f93a745c0 in __GI___poll (fds=0x557e63b720, nfds=6, timeout=<optimized out>) at ../sysdeps/unix/sysv/linux/poll.c:41
41 return SYSCALL_CANCEL (ppoll, fds, nfds, timeout_ts_p, NULL, 0);
(gdb) info thr
Id Target Id Frame
* 1 Thread 0x7f933c4010 (LWP 466) "gdm" 0x0000007f93a745c0 in __GI___poll (fds=0x557e63b720, nfds=6, timeout=<optimized out>) at ../sysdeps/unix/sysv/linux/poll.c:41
2 Thread 0x7f84efeff0 (LWP 468) "gmain" 0x0000007f93a745c0 in __GI___poll (fds=0x557e5d8470, nfds=1, timeout=<optimized out>) at ../sysdeps/unix/sysv/linux/poll.c:41
3 Thread 0x7f7fffeff0 (LWP 469) "gdbus" 0x0000007f93a745c0 in __GI___poll (fds=0x557e620540, nfds=3, timeout=<optimized out>) at ../sysdeps/unix/sysv/linux/poll.c:41
(gdb) bt 2
#0 0x0000007f93a745c0 in __GI___poll (fds=0x557e63b720, nfds=6, timeout=<optimized out>) at ../sysdeps/unix/sysv/linux/poll.c:41
#1 0x0000007f93eed840 in g_main_context_poll (priority=<optimized out>, n_fds=6, fds=0x557e63b720, timeout=<optimized out>, context=0x557e5e3af0) at ../glib/gmain.c:4422
(More stack frames follow...)
(gdb) bt
#0 0x0000007f93a745c0 in __GI___poll (fds=0x557e63b720, nfds=6, timeout=<optimized out>) at ../sysdeps/unix/sysv/linux/poll.c:41
#1 0x0000007f93eed840 in g_main_context_poll (priority=<optimized out>, n_fds=6, fds=0x557e63b720, timeout=<optimized out>, context=0x557e5e3af0) at ../glib/gmain.c:4422
#2 g_main_context_iterate.constprop.0 (context=0x557e5e3af0, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at ../glib/gmain.c:4114
#3 0x0000007f93e96ff0 in g_main_loop_run (loop=0x557e5f1f90) at ../glib/gmain.c:4317
#4 0x000000555c18fed8 in main (argc=<optimized out>, argv=<optimized out>) at ../daemon/main.c:395
(gdb) fr 1
#1 0x0000007f93eed840 in g_main_context_poll (priority=<optimized out>, n_fds=6, fds=0x557e63b720, timeout=<optimized out>, context=0x557e5e3af0) at ../glib/gmain.c:4422
l4422 ret = (*poll_func) (fds, n_fds, timeout);
(gdb) l
4417 LOCK_CONTEXT (context);
4418
4419 poll_func = context->poll_func;
4420
4421 UNLOCK_CONTEXT (context);
4422 ret = (*poll_func) (fds, n_fds, timeout);
4423 errsv = errno;
4424 if (ret < 0 && errsv != EINTR)
4425 {
4426 #ifndef G_OS_WIN32
(gdb) fr 2
#2 g_main_context_iterate.constprop.0 (context=0x557e5e3af0, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at ../glib/gmain.c:4114
4114 g_main_context_poll (context, timeout, max_priority, fds, nfds);
(gdb) p timeout
$1 = 0Versions: (fully updated fedora 33 to updates-testing):
$ rpm -qa | grep -e '^gdm' -e '^gnome' | sort
gdm-3.38.2.1-1.fc33.aarch64
gdm-debuginfo-3.38.2.1-1.fc33.aarch64
gdm-debugsource-3.38.2.1-1.fc33.aarch64
gnome-abrt-1.3.6-5.fc33.aarch64
gnome-autoar-0.2.4-4.fc33.aarch64
gnome-backgrounds-3.38.0-1.fc33.noarch
gnome-bluetooth-3.34.3-1.fc33.aarch64
gnome-bluetooth-libs-3.34.3-1.fc33.aarch64
gnome-calculator-3.38.2-1.fc33.aarch64
gnome-calendar-3.38.2-1.fc33.aarch64
gnome-characters-3.34.0-4.fc33.aarch64
gnome-classic-session-3.38.2-1.fc33.noarch
gnome-clocks-3.38.0-1.fc33.aarch64
gnome-color-manager-3.36.0-3.fc33.aarch64
gnome-contacts-3.38.1-1.fc33.aarch64
gnome-control-center-3.38.2-2.fc33.aarch64
gnome-control-center-filesystem-3.38.2-2.fc33.noarch
gnome-desktop3-3.38.2-1.fc33.aarch64
gnome-disk-utility-3.38.1-1.fc33.aarch64
gnome-font-viewer-3.34.0-5.fc33.aarch64
gnome-getting-started-docs-3.38.0-1.fc33.noarch
gnome-icon-theme-3.12.0-14.fc33.noarch
gnome-initial-setup-3.38.2-1.fc33.aarch64
gnome-keyring-3.36.0-4.fc33.aarch64
gnome-keyring-pam-3.36.0-4.fc33.aarch64
gnome-logs-3.36.0-3.fc33.aarch64
gnome-maps-3.38.2-1.fc33.aarch64
gnome-menus-3.36.0-3.fc33.aarch64
gnome-online-accounts-3.38.0-1.fc33.aarch64
gnome-online-miners-3.34.0-4.fc33.aarch64
gnome-photos-3.38.0-1.fc33.aarch64
gnome-remote-desktop-0.1.9-2.fc33.aarch64
gnome-screenshot-3.38.0-1.fc33.aarch64
gnome-session-3.38.0-1.fc33.aarch64
gnome-session-wayland-session-3.38.0-1.fc33.aarch64
gnome-session-xsession-3.38.0-1.fc33.aarch64
gnome-settings-daemon-3.38.1-1.fc33.aarch64
gnome-shell-3.38.2-5.fc33.aarch64
gnome-shell-extension-apps-menu-3.38.2-1.fc33.noarch
gnome-shell-extension-background-logo-3.37.3-2.fc33.noarch
gnome-shell-extension-common-3.38.2-1.fc33.noarch
gnome-shell-extension-horizontal-workspaces-3.38.2-1.fc33.noarch
gnome-shell-extension-launch-new-instance-3.38.2-1.fc33.noarch
gnome-shell-extension-places-menu-3.38.2-1.fc33.noarch
gnome-shell-extension-window-list-3.38.2-1.fc33.noarch
gnome-software-3.38.0-2.fc33.aarch64
gnome-system-monitor-3.38.0-1.fc33.aarch64
gnome-terminal-3.38.1-2.fc33.aarch64
gnome-terminal-nautilus-3.38.1-2.fc33.aarch64
gnome-themes-extra-3.28-9.fc33.aarch64
gnome-tour-3.38.0-2.fc33.aarch64
gnome-user-docs-3.38.2-1.fc33.noarch
gnome-user-share-3.34.0-4.fc33.aarch64
gnome-video-effects-0.5.0-3.fc33.noarch
gnome-weather-3.36.1-2.fc33.noarchSimilar issue: https://www.reddit.com/r/gnome/comments/k96wzy/help_fedora_33_gdm_use_100_cpu/