X goes blank with SAK SysRq
Raghavendra D Prabhu
raghu.prabhu13 at gmail.com
Fri Jan 13 15:37:24 PST 2012
* On Sat, Jan 14, 2012 at 03:57:09AM +0530, Raghavendra D Prabhu <raghu.prabhu13 at gmail.com> wrote:
>When Ctrl-Alt-Bksp (with zapping) fails to resolve my hang, recently
>I read about SAK which also works as killing all on current console,
>and it is invoked as Alt-SysRq-K .
>However, I noticed that invoking it with X running puts the whole
>system into an unknown state -- blank screen on both monitors with my
>dual setup -- to be resolved only through REISUB SysRq combination.
>I tried SAK without X running and it works fine with getty respawing.
>With X running however it goes into above state, unresolvable without
>a hard reset or REISUB.
>So, is anyone else facing this ? I am running with following
>X.Org X Server 1.11.3
>Release Date: 2011-12-16
>X Protocol Version 11, Revision 0
>Build Operating System: Linux 3.1.5-1-ARCH x86_64
>Current Operating System: Linux Xye 3.2.0-rc7-VYX #142 SMP PREEMPT Thu
>Jan 5 19:18:50 IST 2012 x86_64
>Kernel command line: root=/dev/sda6 ro quiet vga=773 devtmpfs.mount=on
>Build Date: 17 December 2011 09:17:41AM
>Current version of pixman: 0.24.0
> Before reporting problems, check http://wiki.x.org
> to make sure that you have the latest version.
>Also, the graphics driver is nvidia 295.09.
>There is another way to resolve hung X ie with SysRq-E but it kills
>all processes (even daemons) except init which I don't want.
>GPG Id : 0xD72BE977
>Fingerprint: B93F EBCB 8E05 7039 CD3C A4B8 A616 DCA1 D72B E977
Another thing I noticed is that internally kernel sends a SIGKILL
to processes when killing them through a __do_SAK, though I see a
todo over that stating it should first try HUP, then INT and then
KILL. Also it mentions about potential deadlocks due to interrupt
GPG Id : 0xD72BE977
Fingerprint: B93F EBCB 8E05 7039 CD3C A4B8 A616 DCA1 D72B E977
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