326509 2026-10-06 07:02:38 -0700 [GTK] WebKitWebProcess spins at 100% CPU in fontconfig and never renders when WOFF fonts are installed in /usr/share/fonts/woff 2026-10-07 12:01:12 -0700 1 1 1 Unclassified WebKit WebKitGTK Other PC Linux RESOLVED DUPLICATE 325185 https://bugs.webkit.org/show_bug.cgi?id=325185 P2 Normal --- 1 bjorn.regnell webkit-unassigned bugs-noreply fujii mcatanzaro mcrha oldest_to_newest 2259467 0 bjorn.regnell 2026-10-06 07:02:38 -0700 ## Summary With the Debian/Ubuntu package fonts-ebgaramond-extra installed (it installs .woff files in /usr/share/fonts/woff/ebgaramond/), every WebKitWebProcess spins at about 100% CPU and never renders anything. Observed in GNOME Evolution (Flatpak): message preview, message windows and the OAuth login dialog all stay blank, and right-click does nothing. ## Environment Host: Ubuntu 24.04.5 LTS, kernel 6.8.0-146-generic, Intel integrated graphics, reproduced under both X11 and Wayland Flatpak org.gnome.Evolution 3.62.0 on org.gnome.Platform//50 commit: 0bd5091046708e64bc882e8349877cfbae713f6a1e2d0487a5f10af820a2d792 Also reproduced with Evolution 3.60.2 (runtime 50) and 3.60.1 (runtime 49). libwebkit2gtk-4.1.so.0.24.4 (from the runtime), Mesa 26.2.2 GL extension fonts-ebgaramond-extra [version]; about 2,900 fonts installed in total (texlive-full) ## Analysis strace on the spinning WebKitWebProcess: only about 1,100 syscalls in 5 s, so it is busy computing, not looping on syscalls. perf top: most samples are in libfontconfig.so.1.16.0, the rest in libc and libwebkit2gtk (screenshot attached). Not fixed by WEBKIT_DISABLE_DMABUF_RENDERER, WEBKIT_DISABLE_COMPOSITING_MODE, WEBKIT_SKIA_ENABLE_CPU_RENDERING, LIBGL_ALWAYS_SOFTWARE or GDK_BACKEND=x11. Fixed by excluding only the WOFF directory in the app's fontconfig configuration: <selectfont><rejectfont><glob>/run/host/fonts/woff/*</glob></rejectfont></selectfont> Excluding the other host font directories (truetype/noto, type1, X11, cmap, cMap, fonts-go) did not help, while excluding woff alone fixes it. ## Steps to reproduce Install fonts-ebgaramond-extra on the host. Start any WebKitGTK-based Flatpak app on the GNOME 50 runtime (here Evolution) and display HTML content. WebKitWebProcess goes to 100% CPU and the view stays blank. ## Expected Installed WOFF fonts should be skipped or handled without an endless loop in font matching. ## Work-around in Gnome Evolution Add this file: ``` $ cat ~/.var/app/org.gnome.Evolution/config/fontconfig/fonts.conf <?xml version="1.0"?> <!DOCTYPE fontconfig SYSTEM "urn:fontconfig:fonts.dtd"> <fontconfig> <selectfont> <rejectfont> <glob>/run/host/fonts/woff/*</glob> </rejectfont> </selectfont> </fontconfig> ``` 2259471 1 bjorn.regnell 2026-10-06 07:09:21 -0700 Also linked from there to here: https://gitlab.gnome.org/GNOME/evolution/-/work_items/3410 2259474 2 bjorn.regnell 2026-10-06 07:32:21 -0700 Versions: Evolution 3.62.0 (flatpak org.gnome.Evolution, stable) on runtime org.gnome.Platform//50, WebKitGTK 2.54.1 (libwebkit2gtk-4.1.so.0.24.4) Also reproduced with Evolution 3.60.2 on runtime 50, and Evolution 3.60.1 on runtime 49 (older WebKitGTK) Host: Ubuntu 24.04, kernel 6.8, Intel integrated graphics, X11 and Wayland The trigger is the WOFF fonts from the Ubuntu package fonts-ebgaramond-extra in /usr/share/fonts/woff, which the Flatpak sees as /run/host/fonts/woff. Rejecting that folder in ~/.var/app/org.gnome.Evolution/config/fontconfig/fonts.conf fixes it. WebKit bug: https://bugs.webkit.org/show_bug.cgi?id=326509 2260026 3 mcrha 2026-10-07 02:37:24 -0700 Duplicate of bug #325185 2260241 4 mcatanzaro 2026-10-07 12:01:12 -0700 *** This bug has been marked as a duplicate of bug 325185 ***