[systemd-devel] udev and probing of eMMC partition devices

[Alan Perry]

Hi,

I am trying to understand behavior that I am seeing with udev and eMMC 
partition devices and was hoping that someone here could help.

The system that I am running has an eMMC device with something like 7-8 
partitions. The kernel does add block events for the device and each of 
it partitions and the logs show them being queued up by udevd. Then 
things get interesting. Sometimes processing of the add event for the 
device itself gets to a probe step and, in the time frame of the logs 
that I have, never gets further in that processing and the add block 
device events for the partitions are never processed. However, usually, 
it will process the add block device event for the entire device and 
after that (as per the implementation of is_devpath_busy()) start 
processing the add block events for the partition devices. Often times, 
the processing of the partition device add events will get stuck at the 
probe step. The partition devices stuck at the probe are then "waiting" 
and the services that depend on them blocked.

Can anyone here give me some insight into what is going on, in 
particular, how there is such difference in behavior between test runs 
on the same system?

Thanks,

alan perry
Microsoft