I’ve hit an issue, which I believe I’ve now isolated to have come from upgrading fontconfig (and related packages) from 2.12.6-0ubuntu2 to 2.12.6-0ubuntu2.3 from -proposed: if I start Firefox and afterwards start Gparted or Synaptic, Firefox starts eating up all of my CPU. Eventually all letters in the Gparted/Synaptic UI turn into boxes.

Syslog typically then says something like below:

Dec 4 13:41:50 saegusa synaptic.desktop[30027]: (synaptic:30028): Pango-WARNING **: 13:41:50.995: failed to create cairo scaled font, expect ugly output. the offending font is ’DejaVu Sans 11′
Dec 4 13:41:50 saegusa synaptic.desktop[30027]: (synaptic:30028): Pango-WARNING **: 13:41:50.995: font_face status is: out of memory
Dec 4 13:41:50 saegusa synaptic.desktop[30027]: (synaptic:30028): Pango-WARNING **: 13:41:50.995: scaled_font status is: out of memory
Dec 4 13:41:50 saegusa synaptic.desktop[30027]: (synaptic:30028): Pango-WARNING **: 13:41:50.995: shaping failure, expect ugly output. shape-engine=’PangoFcShapeEngine’, font=’DejaVu Sans 11′, text=’Päivitä’
Dec 4 13:41:51 saegusa synaptic.desktop[30027]: (synaptic:30028): Pango-WARNING **: 13:41:51.007: failed to create cairo scaled font, expect ugly output. the offending font is ’DejaVu Sans 11’
Dec 4 13:41:51 saegusa synaptic.desktop[30027]: (synaptic:30028): Pango-WARNING **: 13:41:51.007: font_face status is: out of memory
Dec 4 13:41:51 saegusa synaptic.desktop[30027]: (synaptic:30028): Pango-WARNING **: 13:41:51.007: scaled_font status is: out of memory

The computer has 32 GB of memory and there’s plenty still usable when this occurs, so the OOM seems incorrect to me.

To be sure, I rolled back entirely from -proposed (which caused the issue to go away), then re-enabled -proposed and upgraded just fontconfig, and the issue reappeared.