Surface initialization fails with error.SystemResources after prolonged use

[egalanos]

Issue Description

After running Ghostty for an extended period (days), new terminal tabs/windows fail to initialize with a blank window as per screenshot. The existing terminal tabs/windows continue to work normally.

Diagnostics

Using strace, the failure occurs when Ghostty attempts to create a new io_uring instance for a new surface:

io_uring_setup(256, {flags=0, sq_thread_cpu=0, sq_thread_idle=1000}) = -1 ENOMEM (Cannot allocate memory)

Keyfindings:

Metric	Value
io_uring FDs in affected process	2
VmLck (locked memory)	0 kB
System available RAM	86 GB
System-wide io_uring instances	292

The kernel refuses to create new io_uring instances for the long-running process despite minimal visible io_uring usage and no locked memory.

The io_uring documentation states that RLIMIT_MEMLOCK is used for accounting, but kernels 5.12+ are "less dependent" on it. On kernel 6.17.8, VmLck shows 0 kB, yet io_uring_setup() still returns ENOMEM.

This appears to be unrelated to the previous io_uring speed issue.

Evidence it's per-process:

• Setting gtk-single-instance = false, reloading config, then opening a new Ghostty works
• The new process can create io_uring instances successfully
• Only the original long-running process is affected

Possibly a kernel bug?. I've searched for open liburing issues and kernel issues, but couldn't find anything relevant.

I'm going to switch to epoll now to see if that avoids the issue.

Expected Behavior

Open a new terminal as expected.

Actual Behavior

The new window appears as per screenshot

Reproduction Steps

1. No simple reproduction. It can take hours/days to appear

Ghostty Logs

ghostty[388566]: info(opengl): loaded OpenGL 4.6
ghostty[388566]: warning(gtk_ghostty_surface): failed to initialize surface err=error.SystemResources
ghostty[388566]: warning(gtk_ghostty_surface): surface failed to initialize err=error.SurfaceError

Ghostty Version

Ghostty 1.2.3-1.fc42

Version
  - version: 1.2.3-1.fc42
  - channel: tip
Build Config
  - Zig version   : 0.14.1
  - build mode    : builtin.OptimizeMode.ReleaseFast
  - app runtime   : apprt.Runtime.gtk
  - font engine   : font.main.Backend.fontconfig_freetype
  - renderer      : renderer.generic.Renderer(renderer.OpenGL)
  - libxev        : epoll
  - kernel version: 6.17.8-200.fc42.x86_64
  - desktop env   : gnome
  - GTK version   :
    build         : 4.18.6
    runtime       : 4.18.6
  - libadwaita    : enabled
    build         : 1.7.7
    runtime       : 1.7.8
  - libX11        : enabled
  - libwayland    : enabled

OS Version Information

Fedora release 42 (Adams)

(Linux only) Display Server

Wayland

(Linux only) Desktop Environment/Window Manager

GNOME 48.6

Minimal Ghostty Configuration

theme = Kitty Default
bell-features = system,no-title
shell-integration = none
working-directory = home
command = /bin/bash
linux-cgroup = always

window-width = 132
window-height = 43

Additional Relevant Configuration

Framework desktop 128 GB. GPU: AMD RDNA 3.5 (Radeon 8060S on Ryzen AI Max+ 395)

I have kernel options of amdgpu.gttsize=131072 ttm.pages_limit=33554432 (for running LLMs in case that's relevant)

I acknowledge that:

• I have reviewed the FAQ and confirm that my issue is NOT among them.
• I have searched the Ghostty repository (both open and closed Discussions and Issues) and confirm this is not a duplicate of an existing issue or discussion.
• I have checked the "Preview" tab on all text fields to ensure that everything looks right, and have wrapped all configuration and code in code blocks with a group of three backticks (```) on separate lines.

[rhodes-b]

ghostty says its configured to use epoll it wont use io_uring in that case

[egalanos]

Strangely it is still using io_uring though despite what was printed:

@egalanos ➜ ~ $ ls -la /proc/388566/fd 2>/dev/null | grep io_uring
lrwx------. 1 egalanos egalanos 64 Nov 28 11:49 40 -> anon_inode:[io_uring]
lrwx------. 1 egalanos egalanos 64 Nov 28 11:49 44 -> anon_inode:[io_uring]

And logs from that process:

@egalanos ➜ ~ $ journalctl --user -t ghostty | grep -A5 "388566.*version\|388566.*libxev\|388566.*backend"
Nov 27 13:31:00 parrot ghostty[388566]: info: ghostty version=1.2.3-1.fc42
Nov 27 13:31:00 parrot ghostty[388566]: info: ghostty build optimize=ReleaseFast
Nov 27 13:31:00 parrot ghostty[388566]: info: runtime=apprt.Runtime.gtk
Nov 27 13:31:00 parrot ghostty[388566]: info: font_backend=font.main.Backend.fontconfig_freetype
Nov 27 13:31:00 parrot ghostty[388566]: info: dependency harfbuzz=11.0.0
Nov 27 13:31:00 parrot ghostty[388566]: info: dependency fontconfig=21402
Nov 27 13:31:00 parrot ghostty[388566]: info: renderer=renderer.generic.Renderer(renderer.OpenGL)
Nov 27 13:31:00 parrot ghostty[388566]: info: libxev default backend=io_uring
Nov 27 13:31:00 parrot ghostty[388566]: info(os_locale): setlocale from env result=en_AU.UTF-8
Nov 27 13:31:00 parrot ghostty[388566]: info(gtk): GTK version build=4.18.6 runtime=4.18.6
Nov 27 13:31:00 parrot ghostty[388566]: info(gtk): libadwaita version build=1.7.7 runtime=1.7.8
Nov 27 13:31:00 parrot ghostty[388566]: info: reading configuration file path=/home/egalanos/.config/ghostty/config
Nov 27 13:31:00 parrot ghostty[388566]: info(config): shell src=config value=config.command.Command{ .shell = { 47, 98, 105, 110, 47, 98, 97, 115, 104 } }
Nov 27 13:31:00 parrot ghostty[388566]: info(config): default working directory src=passwd value=/home/egalanos
Nov 27 13:31:00 parrot ghostty[388566]: warning(gtk_ghostty_application): setting GDK_DEBUG=
Nov 27 13:31:00 parrot ghostty[388566]: warning(gtk_ghostty_application): setting GDK_DISABLE=gles-api,vulkan

$ sudo bpftrace -e '
  kprobe:io_uring_setup {
      printf("io_uring_setup called by PID %d (%s)\n", pid, comm);
      printf("  stack: %s\n", kstack);
  }
  kretprobe:io_uring_setup {
      printf("  returned %ld\n", retval);
  }'
Attaching 2 probes...
io_uring_setup called by PID 2739924 (ghostty)
  stack:
        io_uring_setup+1
        do_syscall_64+126
        entry_SYSCALL_64_after_hwframe+118

  returned -12
io_uring_setup called by PID 388566 (ghostty)
  stack:
        io_uring_setup+1
        do_syscall_64+126
        entry_SYSCALL_64_after_hwframe+118

  returned -12

[egalanos]

Actually, the ghostty +version printout is because the libxev io_uring test fails and so it fallsback to epoll.

It looks like it is a system wide issue for my user account rather than a ghostty bug. Small C test prog works for root & nobody, but not my account. So it looks like it's a kernel accounting bug unrelated to Ghostty. I'll close this.

[symptog]

@egalanos how did you solved it locally? I'm facing the same issue.

[symptog]

solved: I had some limits configured in /etc/security/limits.d/. Removed them and it started working.

[egalanos]

@symptog Did you have memlock limits set?

I worked around it with /etc/security/limits.d/99-egalanos.conf

egalanos soft memlock 262144
egalanos hard memlock 262144

and ~/.config/ghostty/config

async-backend = epoll

[nitin88]

I am running into same issue. After few months of usage, the new tab is always hang/stuck randomly.