Bug 1401287 - Xwayland ran into a busy loop [with backtrace, no steps to reproduce]
Summary: Xwayland ran into a busy loop [with backtrace, no steps to reproduce]
Keywords:
Status: CLOSED EOL
Alias: None
Product: Fedora
Classification: Fedora
Component: xorg-x11-server
Version: 25
Hardware: Unspecified
OS: Unspecified
unspecified
urgent
Target Milestone: ---
Assignee: X/OpenGL Maintenance List
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2016-12-04 11:58 UTC by Christian Stadelmann
Modified: 2017-12-12 10:55 UTC (History)
2 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2017-12-12 10:55:57 UTC
Type: Bug


Attachments (Terms of Use)
A backtrace from running `t a a bt full` in gdb attached to Xwayland (8.51 KB, text/plain)
2016-12-04 11:58 UTC, Christian Stadelmann
no flags Details
A backtrace from running `t a a bt full` in gdb attached to Xwayland (2) (8.57 KB, text/plain)
2016-12-04 15:59 UTC, Christian Stadelmann
no flags Details

Description Christian Stadelmann 2016-12-04 11:58:34 UTC
Created attachment 1227904 [details]
A backtrace from running `t a a bt full` in gdb attached to Xwayland

Version-Release number of selected component (if applicable):
xorg-x11-server-Xwayland-1.19.0-1.fc25.x86_64
gnome-shell-3.22.2-2.fc25.x86_64
mutter-3.22.2-1.fc25.x86_64
libwayland-client-1.12.0-1.fc25.x86_64
gtk3-3.22.4-1.fc25.x86_64
kernel-4.8.6-300.fc25.x86_64

How reproducible:
I don't know, I think it happens several times a day.

Steps to Reproduce:
no idea.

Actual results:
I noted that firefox was frozen and even drew its menu on a wrong workspace. Some other applications (like gnome-terminal, gnome-system-monitor) still worked fine. I noted that Xwayland was running at 100% CPU load on one core. Then I attached gdb to it (from a different tty) and took a backtrace:

0x000000000058a792 in TimerSet (timer=0x4f33740, timer@entry=0x0, flags=flags@entry=0, millis=12481115, millis@entry=38, func=func@entry=0x4f4500 <present_fake_do_timer>, arg=arg@entry=0x4f33710) at WaitFor.c:348
348	    xorg_list_for_each_entry_safe(existing, tmp, &timers, list)
#0  0x000000000058a792 in TimerSet (timer=0x4f33740, timer@entry=0x0, flags=flags@entry=0, millis=12481115, millis@entry=38, func=func@entry=0x4f4500 <present_fake_do_timer>, arg=arg@entry=0x4f33710) at WaitFor.c:348
#1  0x00000000004f464a in present_fake_queue_vblank (screen=0x1e74980, event_id=679993, msc=<optimized out>) at present_fake.c:109
#2  0x00000000004f4171 in present_pixmap (window=0x2897010, pixmap=pixmap@entry=0x0, serial=160895, valid=valid@entry=0x0, update=update@entry=0x0, x_off=x_off@entry=0, y_off=0, target_crtc=0x0, wait_fence=0x0, idle_fence=0x0, options=0, 
    window_msc=0, divisor=2, remainder=0, notifies=0x0, num_notifies=0) at present.c:956
#3  0x00000000004f43de in present_notify_msc (window=<optimized out>, serial=<optimized out>, target_msc=<optimized out>, divisor=<optimized out>, remainder=<optimized out>) at present.c:1014
#4  0x00000000004f4c85 in proc_present_notify_msc (client=0x2e1f9c0) at present_request.c:174
#5  0x0000000000556715 in Dispatch () at dispatch.c:469
#6  0x000000000055a698 in dix_main (argc=10, argv=0x7ffe136363b8, envp=<optimized out>) at main.c:287
#7  0x00007fca84827401 in __libc_start_main (main=0x423d50 <main>, argc=10, argv=0x7ffe136363b8, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7ffe136363a8) at ../csu/libc-start.c:289
#8  0x0000000000423d8a in _start ()

(long version is attached)

Expected results:
No busy loop.

Additional info:
Weirdly, gnome-shell was working fine for a while until I killed it which may not have been necessary.

Comment 1 Christian Stadelmann 2016-12-04 15:59:11 UTC
Created attachment 1227938 [details]
A backtrace from running `t a a bt full` in gdb attached to Xwayland (2)

Happened again. Firefox was only responding very slow to input (like 2…20 seconds delay), other Xwayland applications worked fine. After taking the backtrace I could close firefox with Ctrl+Q and log out without problems, no data loss involved.

Comment 2 Olivier Fourdan 2016-12-05 08:40:01 UTC
When that happens, if you kill firefox, does it recover (I mean, without logging out)?

Comment 3 Christian Stadelmann 2016-12-12 18:03:32 UTC
(In reply to Olivier Fourdan from comment #2)
> When that happens, if you kill firefox, does it recover (I mean, without
> logging out)?

I didn't run into this bug any more.

Is it possible that this issue is caused by a faulty gnome-settings-daemon?

Comment 4 Olivier Fourdan 2016-12-13 08:26:57 UTC
(In reply to Christian Stadelmann from comment #3)
> (In reply to Olivier Fourdan from comment #2)
> > When that happens, if you kill firefox, does it recover (I mean, without
> > logging out)?
> 
> I didn't run into this bug any more.
> 
> Is it possible that this issue is caused by a faulty gnome-settings-daemon?

Unlikely g-s-d, but an X client can hammer the X server.

If this is the case and you kill the client, the X server (Xwayland in our case) would be able to recover (sometimes after a short while), that's why I asked if killing the client allows to recover. If it recovers then it is possibly a client issue more than a server issue.

Comment 5 Fedora End Of Life 2017-11-16 19:53:27 UTC
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Comment 6 Fedora End Of Life 2017-12-12 10:55:57 UTC
Fedora 25 changed to end-of-life (EOL) status on 2017-12-12. Fedora 25 is
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