In the Linux kernel, the following vulnerability has been resolved:
fs/proc: fix softlockup in _readvmcore (part 2)
Since commit 5cbcb62dddf5 ("fs/proc: fix softlockup in _readvmcore") the number of softlockups in _readvmcore at kdump time have gone down, but they still happen sometimes.
In a memory constrained environment like the kdump image, a softlockup is not just a harmless message, but it can interfere with things like RCU freeing memory, causing the crashdump to get stuck.
The second loop in _readvmcore has a lot more opportunities for natural sleep points, like scheduling out while waiting for a data write to happen, but apparently that is not always enough.
Add a condresched() to the second loop in _read_vmcore to (hopefully) get rid of the softlockups.