When I attempt to do a modules-update (or emerge a kernel module), my system stops. I tracked down the bug, and this is what it is. It may be specific to my system. In trying to resolve device char-major-195 (the nvidia driver), function resolve_alias in generate-modprobe.conf goes into infinite recursion, which causes bash to fork indefinitely, choking the system until a reboot is done. The line in question is the first and last lines (68 and 74): resolve_alias() { RA_RESOLVE=`grep "^alias[ ][ ]*$2[ ]" -- $1 | awk '{ print $3 }'` ... # Recurse. (resolve_alias $1 "$RA_RESOLVE") } $1 is a temporary file /tmp/modprobe.XXXXXX . $2 is the symbol to resolve. Here are the relevant lines of /tmp/modprobe.XXXXXX: # Old nvidia support ... alias char-major-195 NVdriver alias char-major-195 nvidia # To enable Side Band Adressing: NVreg_EnableAGPSBA=1 #options nvidia NVreg_EnableAGPSBA=1 NVreg_EnableAGPFW=1 #options nvidia NVreg_SoftEDIDs=0 NVreg_Mobile=3 The first two lines were imported from /etc/modules.d/aliases in package sys-apps/baselayout-1.12.6. The last 4 lines were imported from /etc/modules.d/nvidia in package x11-drivers/nvidia-drivers-1.0.8776. Here is a run-down of what happens: In the course of normal events, resolve_aliases is called to resolve char-major-195 like so: resolve_alias /tmp/modprobe.XXXXXX char-major-195 grep finds the two lines: alias char-major-195 NVdriver alias char-major-195 nvidia and awk strips that to: NVdriver nvidia Since that is not empty, resolve_alias is called recursively, but with a malformed second argument (unexpected embedded newline): resolve_alias /tmp/modprobe.XXXXXX 'NVdriver nvidia' this wrecks havoc since that argument is used in a regular expression. the grep command is now grep '^alias[ ][ ]*NVdriver nvidia[ ]' -- /tmp/modprobe.XXXXXX in my grep, the newline in argument 1 is treated like an or, so grep finds a match to either of the two incorrect regular expressions (this may be a bug in grep). It now matches these three lines, all of which are comments: # Old nvidia support ... #options nvidia NVreg_EnableAGPSBA=1 NVreg_EnableAGPFW=1 #options nvidia NVreg_SoftEDIDs=0 NVreg_Mobile=3 awk reduces this to: nvidia NVreg_EnableAGPSBA=1 NVreg_SoftEDIDs=0 since this is still not empty, resolve_aliases is recursively called again, this time with a completely bogus second argument: resolve_alias /tmp/modprobe.XXXXXX 'nvidia NVreg_EnableAGPSBA=1 NVreg_SoftEDIDs=0' grep finds: # To enable Side Band Adressing: NVreg_EnableAGPSBA=1 #options nvidia NVreg_EnableAGPSBA=1 NVreg_EnableAGPFW=1 #options nvidia NVreg_SoftEDIDs=0 NVreg_Mobile=3 resolve_aliases is called again: resolve_alias /tmp/modprobe.XXXXXX 'enable NVreg_EnableAGPSBA=1 NVreg_SoftEDIDs=0' grep finds the same three lines as before: # To enable Side Band Adressing: NVreg_EnableAGPSBA=1 #options nvidia NVreg_EnableAGPSBA=1 NVreg_EnableAGPFW=1 #options nvidia NVreg_SoftEDIDs=0 NVreg_Mobile=3 and resolve_alias is called with the same arguments as before, starting the endless forking bash recursion that killed my computer several times: resolve_alias /tmp/modprobe.XXXXXX 'nvidia NVreg_EnableAGPSBA=1 NVreg_SoftEDIDs=0' I am not sure what the proper solution is. Perhaps it is wrong that /etc/modules.d/aliases and /etc/modules.d/nvidia contain competing aliases of char-major-195. Perhaps it is wrong that the output of grep is not limited to one line via head or tail. It is probably wrong that grep treats a newline like an OR operation. I don't know. As a workaround to enable emerging, I commented out the competing line in /etc/modules.d/aliases.
*** This bug has been marked as a duplicate of 149426 ***
