I've found the problem.
Short answer
The problem was that I installed kernel rpm (B) over already installed kernel rpm (A), without removing it first.
Detaild answer
scsi_mod.ko
was owned only by (A). While installing (B), scsi_mod.ko
was in /lib/modules/.
When intramfs was created in (B)'s postinstall script. depmod decided that scsi_wait_scan.ko
depends on scsi_mod.ko
, while both build against different configurations.
Later when booting the machine, kernel started run initramfs. This in turn modprob'ed scsi_wait_scan.ko
. modprobe tried loaded as a consiquence scsi_mod.ko
, which is not appropriate to the current kernel, thus resulting to error I saw.