https://bugs.kde.org/show_bug.cgi?id=441077
Bug ID: 441077
Summary: Plasmashell panels may freeze, usually unrelated but
unresponsive NFS/SMB mounts are involved
Product: plasmashell
Version: 5.21.5
Platform: Other
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: Panel
Assignee: plasma-b...@kde.org
Reporter: k...@kaishome.de
Target Milestone: 1.0
Created attachment 140790
--> https://bugs.kde.org/attachment.cgi?id=140790&action=edit
thread apply all bt
SUMMARY
Plasmashell tends to hang/completely freeze when a mounted network file system
temporarily does not respond. Most of the times, the panels will recover after
some minutes but sometimes they don't.
I've now seen a freeze which didn't recover and I had to SIGKILL plasmashell to
restart it, even `--replace` did not work. I'm not sure if a mounted file
system was involved this time (see Additional Information below).
Take note that the network mounts are completely unrelated, there's nothing on
the panel that even loads data from it.
In earlier versions this was also caused by plasma widgets loading data from
network while the internet connection temporarily stalled. I've since removed
all widgets that load data from network (like the weather widget). But I
believe this incident may be caused by the disk usage warning plugin of plasma
when it tries to access disk usage data from a non-responding mount.
Conclusion: Plasma should not block and maybe wrap a timeout handler around
queries that may potentially stall due to external reasons. However, this
incident may be different.
A plasma dev may have better insights. I'll attach a short and full gdb
backtrace I was able to fetch from the hanging pid.
Possible bug reports covering the mount-related issue but probably not a
duplicate of this:
#413110, #416972, #272361
STEPS TO REPRODUCE
0. The backtrace may not be about this particular hang:
1. Use network mounts somewhere below your home directory
2. Cut the network connection to stall access to these mounts
3. Observe plasmashell freezing and recovering minutes later
OBSERVED RESULT
Plasma panels stop responding to clicks and freeze with whatever content they
did currently render.
EXPECTED RESULT
Plasma should detect timeouts and recover in one or another way, as a last
resort it could kill itself and restart - which helped in this particular case:
I SIGKILLed it and restarted it.
SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Gentoo Linux
(available in About System)
KDE Plasma Version: 5.21.5
KDE Frameworks Version: 5.82.0
Qt Version: 5.15.2
ADDITIONAL INFORMATION
This particular freeze may be related to this dmesg entry:
[686470.331086] BUG: unable to handle page fault for address: 000000020ee80000
[686470.331091] #PF: supervisor write access in kernel mode
[686470.331092] #PF: error_code(0x0002) - not-present page
[686470.331093] PGD 0 P4D 0
[686470.331096] Oops: 0002 [#1] PREEMPT SMP
[686470.331098] CPU: 1 PID: 1919 Comm: QSGRenderThread Not tainted
5.10.57-gentoo #1
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