Why does SaK kill gdm, which is running on a different VT?

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I run Fedora Linux 28, and have enabled sysrq. I pressed Alt+PrtScr+K, to kill a non-responsive X session. But this also restarted gdm, and one other X session, which were running on different VTs. Why?

asked Jun 21 at 15:48

sourcejedi

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asked Jun 21 at 15:48

sourcejedi

18.1k22375

add a commentÂ |Â

up vote
0
down vote

favorite

asked Jun 21 at 15:48

sourcejedi

18.1k22375

asked Jun 21 at 15:48

sourcejedi

18.1k22375

asked Jun 21 at 15:48

sourcejedi

18.1k22375

asked Jun 21 at 15:48

sourcejedi

18.1k22375

asked Jun 21 at 15:48

sourcejedi

18.1k22375

add a commentÂ |Â

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Linux SaK kills all processes which have the current tty open.

See https://elixir.bootlin.com/linux/v4.17/source/drivers/tty/tty_io.c#L2700

systemd-logind appears to open all active ttys.

You can verify this using lsof.

When X is run as an unprivileged user and relies on systemd-logind, it does not handle a restart of systemd-logind. When X loses its connection to systemd-logind, it terminates itself.

Alternative

So SaK can indirectly affect all VTs, if you use unprivileged X, or Wayland.

Instead, you can use Alt+PrtScr+R, then Ctrl+Alt+F6. You can log in on the text console, and manually kill processes e.g. Xorg, or gnome-shell if you use a GNOME Wayland session).

edited Jun 21 at 15:54

answered Jun 21 at 15:48

sourcejedi

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1 Answer
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active

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1 Answer
1

active

oldest

votes

up vote
1
down vote

accepted

Linux SaK kills all processes which have the current tty open.

See https://elixir.bootlin.com/linux/v4.17/source/drivers/tty/tty_io.c#L2700

systemd-logind appears to open all active ttys.

You can verify this using lsof.

When X is run as an unprivileged user and relies on systemd-logind, it does not handle a restart of systemd-logind. When X loses its connection to systemd-logind, it terminates itself.

Alternative

So SaK can indirectly affect all VTs, if you use unprivileged X, or Wayland.

Instead, you can use Alt+PrtScr+R, then Ctrl+Alt+F6. You can log in on the text console, and manually kill processes e.g. Xorg, or gnome-shell if you use a GNOME Wayland session).

edited Jun 21 at 15:54

answered Jun 21 at 15:48

sourcejedi

18.1k22375

add a commentÂ |Â

up vote
1
down vote

accepted

Linux SaK kills all processes which have the current tty open.

See https://elixir.bootlin.com/linux/v4.17/source/drivers/tty/tty_io.c#L2700

systemd-logind appears to open all active ttys.

You can verify this using lsof.

When X is run as an unprivileged user and relies on systemd-logind, it does not handle a restart of systemd-logind. When X loses its connection to systemd-logind, it terminates itself.

Alternative

So SaK can indirectly affect all VTs, if you use unprivileged X, or Wayland.

Instead, you can use Alt+PrtScr+R, then Ctrl+Alt+F6. You can log in on the text console, and manually kill processes e.g. Xorg, or gnome-shell if you use a GNOME Wayland session).

edited Jun 21 at 15:54

answered Jun 21 at 15:48

sourcejedi

18.1k22375

add a commentÂ |Â

up vote
1
down vote

accepted

Linux SaK kills all processes which have the current tty open.

See https://elixir.bootlin.com/linux/v4.17/source/drivers/tty/tty_io.c#L2700

systemd-logind appears to open all active ttys.

You can verify this using lsof.

When X is run as an unprivileged user and relies on systemd-logind, it does not handle a restart of systemd-logind. When X loses its connection to systemd-logind, it terminates itself.

Alternative

So SaK can indirectly affect all VTs, if you use unprivileged X, or Wayland.

Instead, you can use Alt+PrtScr+R, then Ctrl+Alt+F6. You can log in on the text console, and manually kill processes e.g. Xorg, or gnome-shell if you use a GNOME Wayland session).

edited Jun 21 at 15:54

answered Jun 21 at 15:48

sourcejedi

18.1k22375

Linux SaK kills all processes which have the current tty open.

See https://elixir.bootlin.com/linux/v4.17/source/drivers/tty/tty_io.c#L2700

systemd-logind appears to open all active ttys.

You can verify this using lsof.

When X is run as an unprivileged user and relies on systemd-logind, it does not handle a restart of systemd-logind. When X loses its connection to systemd-logind, it terminates itself.

Alternative

So SaK can indirectly affect all VTs, if you use unprivileged X, or Wayland.

Instead, you can use Alt+PrtScr+R, then Ctrl+Alt+F6. You can log in on the text console, and manually kill processes e.g. Xorg, or gnome-shell if you use a GNOME Wayland session).

edited Jun 21 at 15:54

answered Jun 21 at 15:48

sourcejedi

18.1k22375

edited Jun 21 at 15:54

answered Jun 21 at 15:48

sourcejedi

18.1k22375

answered Jun 21 at 15:48

sourcejedi

18.1k22375

answered Jun 21 at 15:48

sourcejedi

18.1k22375

add a commentÂ |Â

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