kern/60083: swap encryption break /dev/drum

["imuwoto%gmail.com@localhost via gnats" <gnats-admin%NetBSD.org@localhost>]

>Number:         60083
>Category:       kern
>Synopsis:       swap encryption break /dev/drum
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Mar 15 03:35:00 +0000 2026
>Originator:     YAMAMOTO Takashi
>Release:        -current
>Organization:
>Environment:
amd64
>Description:
swap encryption is implemented in uvm_swap_io.
it seems conceptually wrong because /dev/drum users like libkvm
need to see unencrypted data.

>How-To-Repeat:
read /dev/drum to obtain swapped-out data as libkvm sometimes does.
>Fix:
implement it under /dev/drum.