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

The name of the pictureThe name of the pictureThe name of the pictureClash Royale CLAN TAG#URR8PPP











up vote
0
down vote

favorite












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?




linux gdm magic-sysrq




share|improve this question























    up vote
    0
    down vote

    favorite












    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?




    linux gdm magic-sysrq




    share|improve this question





















      up vote
      0
      down vote

      favorite









      up vote
      0
      down vote

      favorite











      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?




      linux gdm magic-sysrq




      share|improve this question











      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?





      linux gdm magic-sysrq





      share|improve this question










      share|improve this question




      share|improve this question









      asked Jun 21 at 15:48









      sourcejedi

      18.1k22375




      18.1k22375




















          1 Answer
          1






          active

          oldest

          votes

















          up vote
          1
          down vote



          accepted











          1. 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




          2. systemd-logind appears to open all active ttys.



            You can verify this using lsof.



          3. 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).






          share|improve this answer























            Your Answer







            StackExchange.ready(function()
            var channelOptions =
            tags: "".split(" "),
            id: "106"
            ;
            initTagRenderer("".split(" "), "".split(" "), channelOptions);

            StackExchange.using("externalEditor", function()
            // Have to fire editor after snippets, if snippets enabled
            if (StackExchange.settings.snippets.snippetsEnabled)
            StackExchange.using("snippets", function()
            createEditor();
            );

            else
            createEditor();

            );

            function createEditor()
            StackExchange.prepareEditor(
            heartbeatType: 'answer',
            convertImagesToLinks: false,
            noModals: false,
            showLowRepImageUploadWarning: true,
            reputationToPostImages: null,
            bindNavPrevention: true,
            postfix: "",
            onDemand: true,
            discardSelector: ".discard-answer"
            ,immediatelyShowMarkdownHelp:true
            );



            );








             

            draft saved


            draft discarded


















            StackExchange.ready(
            function ()
            StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2funix.stackexchange.com%2fquestions%2f451136%2fwhy-does-sak-kill-gdm-which-is-running-on-a-different-vt%23new-answer', 'question_page');

            );

            Post as a guest

















            1 Answer
            1






            active

            oldest

            votes








            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes








            up vote
            1
            down vote



            accepted











            1. 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




            2. systemd-logind appears to open all active ttys.



              You can verify this using lsof.



            3. 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).






            share|improve this answer



























              up vote
              1
              down vote



              accepted











              1. 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




              2. systemd-logind appears to open all active ttys.



                You can verify this using lsof.



              3. 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).






              share|improve this answer

























                up vote
                1
                down vote



                accepted







                up vote
                1
                down vote



                accepted







                1. 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




                2. systemd-logind appears to open all active ttys.



                  You can verify this using lsof.



                3. 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).






                share|improve this answer
















                1. 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




                2. systemd-logind appears to open all active ttys.



                  You can verify this using lsof.



                3. 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).







                share|improve this answer















                share|improve this answer



                share|improve this answer








                edited Jun 21 at 15:54


























                answered Jun 21 at 15:48









                sourcejedi

                18.1k22375




                18.1k22375






















                     

                    draft saved


                    draft discarded


























                     


                    draft saved


                    draft discarded














                    StackExchange.ready(
                    function ()
                    StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2funix.stackexchange.com%2fquestions%2f451136%2fwhy-does-sak-kill-gdm-which-is-running-on-a-different-vt%23new-answer', 'question_page');

                    );

                    Post as a guest
































































                    -

                    Popular posts from this blog

                    How to check contact read email or not when send email to Individual?

                    Image
                    Clash Royale CLAN TAG #URR8PPP up vote 1 down vote favorite I'm using WordPress 4.9.8, CiviCRM to 5.5.1, I usually send email to contact by Search> Find contacts View contact details Action> Send email Send email ok, Contact received mail ok like picture But status only Email sent though contact read email or not. So, can CiviCRM can change status to Email read when contact read email? wordpress email share | improve this question asked Sep 26 at 0:12 ToanLuong 49 9 add a comment  |  up vote 1 down vote favorite I'm using WordPress 4.9.8, CiviCRM to 5.5.1, I usually send email to contact by Search> Find contacts View contact details Action> Send email Send email ok, Contact received mail ok like picture But status only Email sent though contact read email or not. So, can CiviCRM can change status to Email read when contact read email? wordpress email share | improve this questi...
                    Read more

                    Displaying single band from multi-band raster using QGIS

                    Image
                    Clash Royale CLAN TAG #URR8PPP 1 How can I extract a single band from multi-band raster in QGIS? I have an remote sensed image which has 6 bands (including NDVI band), I want to display each band separately, but have no idea how to do. I have seen some questions similar here but none worked for me. The original image (has 6 bands) is: I want to display the band 6 which should be like this: But I tried gdal_translate, and couldn't get the correct result. What I have got is: qgis raster multi-band share | improve this question edited Mar 5 at 0:53 Summer asked Mar 4 at 6:42 Summer Summer 23 6 Is this any help gis.stackexchange.com/questions/220658/… ? if not gis.stackexchange.com/questions/62133/… might help. – Michael Stimson Mar 4 at 6:46 Thanks for answering but when I used gdal_translate, qgis showed that 'Error 4: Kayena.tif: No such file or directory". Would you know how to fi...
                    Read more

                    How many registers does an x86_64 CPU actually have?

                    Image
                    Clash Royale CLAN TAG #URR8PPP up vote 2 down vote favorite I am currently learning reverse engineering and am studying the flags register. I had in my mind that rflags was just another name for one of the 16 general purpose registers, for example rax or rbx . But it looks like rflags is actually an additional register. So that makes 17 registers in total... how many more could there be? I have spent at least an hour on this and found numerous different answers. The best answer so far is this, which says that there are 40 registers in total. 16 General Purpose Registers 2 Status Registers 6 Code Segment Registers 16 SSE Registers 8 FPU/MMX Registers But if I add that up, I get 48. Could anybody provide an official answer on how many registers an x86_64 CPU has (e.g. an Intel i7). Additionally, I have seen references to 'hardware' and 'architectural' registers. What are those registers and how many are there? register x86-64 share | improve this...
                    Read more