https://bugs.kde.org/show_bug.cgi?id=497318
Bug ID: 497318
Summary: Dragging window between the corners of two displays
causes KWin to hang
Classification: Plasma
Product: kwin
Version: git master
Platform: Other
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: wayland-generic
Assignee: kwin-bugs-n...@kde.org
Reporter: m...@aidanharr.is
Target Milestone: ---
Created attachment 176519
--> https://bugs.kde.org/attachment.cgi?id=176519&action=edit
gdb.txt
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SUMMARY
KWin hangs and spends a lot of CPU time in KWin::Window::nextInteractive.
Something is spinning the CPU in KWin or Qt and causing it to lockup.
The GPU driver is fine as far as I can tell, there's nothing printed in dmesg
and the kwin_wayland_wr process restarts KWin correctly if I kill it with
`pkill -9 -x kwin_wayland`. Looks like an issue in KWin or Qt somewhere.
This is what `perf top -p $(pgrep -x kwin_wayland)` reports:
62.38% libkwin.so.6.2.80 [.] KWin::Window::nextInteractive
24.32% libQt6Core.so.6.8.1 [.] QRect::operator&
6.02% libQt6Gui.so.6.8.1 [.] QRegion::end
3.41% libQt6Gui.so.6.8.1 [.] QRegion::begin
1.34% libkwin.so.6.2.80 [.] QRegion::end
1.33% libkwin.so.6.2.80 [.] QRect::operator&
0.97% libkwin.so.6.2.80 [.] QRegion::begin
0.01% [kernel] [k] tick_do_update_jiffies64
0.01% [kernel] [k] srso_alias_return_thunk
0.01% [kernel] [k] update_rt_rq_load_avg
0.01% [kernel] [k] read_tsc
0.01% [kernel] [k] amdgpu_dm_irq_handler
0.01% [kernel] [k] dm_dcn_vertical_interrupt0_high_irq
0.01% [kernel] [k] srso_alias_safe_ret
0.00% [kernel] [k] update_vsyscall
0.00% [kernel] [k] amdgpu_irq_handler
0.00% [kernel] [k] dm_write_reg_func
0.00% [kernel] [k] to_dal_irq_source_dcn30
0.00% [kernel] [k] navi10_ih_get_wptr
0.00% [kernel] [k] ktime_get_update_offsets_now
0.00% [kernel] [k] hrtimer_interrupt
0.00% [kernel] [k] sched_clock_cpu
0.00% [kernel] [k] sched_clock
0.00% [kernel] [k] irqtime_account_irq
0.00% [kernel] [k] preempt_count_add
0.00% [kernel] [k] __sysvec_apic_timer_interrupt
0.00% [kernel] [k] preempt_count_sub
0.00% [kernel] [k] native_sched_clock
0.00% [kernel] [k] __irq_exit_rcu.llvm.13343355091959174
0.00% [kernel] [k] timekeeping_advance.llvm.758212563608
0.00% [kernel] [k] asm_sysvec_apic_timer_interrupt
0.00% [kernel] [k] __handle_irq_event_percpu
0.00% [kernel] [k] event_interrupt_isr_v10.llvm.18313402
0.00% [kernel] [k] _raw_spin_unlock_irqrestore
0.00% [kernel] [k] sched_balance_trigger
STEPS TO REPRODUCE
I can semi-reliably reproduce by dragging a Firefox window but it's not 100%. I
can't make it happen on-demand.
SOFTWARE/OS VERSIONS
Operating System: Gentoo 2.17
KDE Plasma Version: 6.2.80
KDE Frameworks Version: 6.10.0
Qt Version: 6.8.1
Kernel Version: 6.12.4-zen1 (64-bit)
Graphics Platform: Wayland
Processors: 32 × AMD Ryzen 9 5950X 16-Core Processor
Memory: 62.7 GiB of RAM
Graphics Processor: AMD Radeon RX 6700 XT
Manufacturer: ASUS
ADDITIONAL INFORMATION
I stepped about in Gdb a bit and it seems stuck in QRect somewhere, but it's
beyond me. I'll attach the gdb log file to this report.
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