Comment 42 for bug 217815

A couple of points worth mulling over to corner this one..

1. Is the "hanging" a function of memory size - for example, the buffer cache filling up after a certain amount of time and then pdflush kicking in very aggressively doing dirty data writing backs as fast as it can. In which case, one may see the system resume again after a (long) period of time once pdflush is complete. It may be worth tweaking with the /proc/sys/vm/dirty* options to see if this trips the problem more frequently. Also, it may be worth seeing if doing the install with small memory kvm virtual machines shows this problem earlier than large memory virtual machines just to see if it is a buffer cache write back cpu starvation issue.

2. From my understanding dd is being used to zero the encrypted disk. Does changing the dd block size to a very large size trip this bug earlier as one gets more throughput than the normal (small) block size default?

3. Is the hanging resumed by an external interrupt (keyboard, mouse) because of the scheduler boosts interactive sessions temporarily and hence interfering (in a positive way) to the balancing of the encryption kernel space thread, dd and pdflush?