The kernel's memory usage is typically pretty small, unless you're considering the page cache to be part of it.
Although: I once investigated a soft freeze on a realtime-patched Linux system that turned out to be caused by a vendor's software somehow managing to indefinitely stall an RCU grace period, eventually consuming all available memory on the system. The kernel core dump being over 4GB in size was a bit of a give-away.
Although: I once investigated a soft freeze on a realtime-patched Linux system that turned out to be caused by a vendor's software somehow managing to indefinitely stall an RCU grace period, eventually consuming all available memory on the system. The kernel core dump being over 4GB in size was a bit of a give-away.