Red Hat Bugzilla – Bug 496721
Stuck application can "absorb" all mouse clicks and keypresses, killing it causes X to restart
Last modified: 2018-04-11 10:10:16 EDT
Created attachment 340425 [details]
Description of problem:
Recently I encountered Bug 496367. This causes Pidgin to spin at 100% CPU load and otherwise be un-responsive to mouse and keyboard events. Before it got caught in this loop, I opened a drop-down menu from its window. When Pidgin became unresponsive, so did the rest of the desktop. The screen was still updating and the cursor still moved, but clicks and keypresses did not register.
So I switched to a text-console and killed Pidgin. This caused X to restart.
Compiz was enabled at the time.
Version-Release number of selected component (if applicable):
Always (following the description above).
Steps to Reproduce:
1. Provoke a situation where a misbehaving application has monopolised mouse clicks and keypresses.
2. Switch VT to a text console.
3. Kill the application.
Misbehaving applications unable to lock out the desktop in this manner.
X robust to errant applications being killed.
I've attached an Xorg.0.log, but I don't think it contains anything relevant.
There is no xorg.conf.
I don't know, how much it helps, but if you are able to reproduce it, could you try to run pidgin with --debug parameter and then send as the stdout/stderr from that? It might tell us a little bit more what was going on while pidgin was falling crazy.
Changing component back to server - the mouse driver isn't used in this setup.
Is this log from the crash? Usually there's some backtrace in there when it crashes. Next time this happens, please check the Xorg.log.0.old for a backtrace too.
(In reply to comment #0)
> Expected results:
> Misbehaving applications unable to lock out the desktop in this manner.
that can't be fixed in the server. the app uses a grab for the popup menu, and grabs are to provide the application with exclusive access to the input events. if the app never releases said grab, then this needs to be fixed in the application.
nonetheless, the server crash shouldn't happen.
(In reply to comment #2)
> Changing component back to server - the mouse driver isn't used in this setup.
> Is this log from the crash? Usually there's some backtrace in there when it
> crashes. Next time this happens, please check the Xorg.log.0.old for a
> backtrace too.
The log I posted was actually a .old, but the attachment's description doesn't reflect this. I also scoured /var/log/messages and couldn't find anything of relevance. I'll have another go later and see if I can provoke it.
> that can't be fixed in the server. the app uses a grab for the popup menu, and
> grabs are to provide the application with exclusive access to the input events.
> if the app never releases said grab, then this needs to be fixed in the
OK, but is there any way more elegant than resorting to a VT switch or ssh and kill -9 to break a grab when an application goes off on one? (Some other apps I know can cause "momentary losses of usefulness" this way particularly when doing drag-and-drop.)
(In reply to comment #3)
> OK, but is there any way more elegant than resorting to a VT switch or ssh and
> kill -9 to break a grab when an application goes off on one?
Not really, tbh. there used to be a kill grab hotkey hardcoded in X, but it was a security issue and removed for that reason.
This bug appears to have been reported against 'rawhide' during the Fedora 11 development cycle.
Changing version to '11'.
More information and reason for this action is here:
Since this bugzilla report was filed, there have been several major updates in various components of the Xorg system, which may have resolved this issue. Users who have experienced this problem are encouraged to upgrade their system to the latest version of their packages. For packages from updates-testing repository you can use command
yum upgrade --enablerepo='*-updates-testing'
Alternatively, you can also try to test whether this bug is reproducible with the upcoming Fedora 12 distribution by downloading LiveMedia of F12 Beta available at http://alt.fedoraproject.org/pub/alt/nightly-composes/ . By using that you get all the latest packages without need to install anything on your computer. For more information on using LiveMedia take a look at https://fedoraproject.org/wiki/FedoraLiveCD .
Please, if you experience this problem on the up-to-date system, let us now in the comment for this bug, or whether the upgraded system works for you.
If you won't be able to reply in one month, I will have to close this bug as INSUFFICIENT_DATA. Thank you.
[This is a bulk message for all open Fedora Rawhide Xorg-related bugs. I'm adding myself to the CC list for each bug, so I'll see any comments you make after this and do my best to make sure every issue gets proper attention.]
Could you please reply to the previous question? If you won't reply in one month, I will have to close this bug as INSUFFICIENT_DATA. Thank you.
[Note please, that this is machine generated comment for large amount of bugs; due to some technical issues, it is possible we've missed some of the responses -- it is happens, please, just a make a comment about that; that we will see. Thank you]
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