Do not access pv_table array for fictitious pages ...

[kib]

Summary

... since the array does not cover the dynamically registered ficititious ranges.

Reported and tested by: Michael Butler <[e-mail]>

[alc]

I have one suggestion about the implementation. Instead of adding new conditionals, create a global, dummy "struct md_page" and conditionally initialize pvh to point to this dummy struct rather than pa_to_pvh(...) before acquiring the pv list lock.

[kib]

Use dummy struct md_page for checking generation number of the (nonexistent) superpage pv list for fictitious managed pages.

[alc]

sys/amd64/amd64/pmap.c

3928–3929

If we statically initialize pv_dummy's pv_list field to an empty state, then this "if" statement can be eliminated.

5749–5750

Same here.

5881–5882

Here I think that the "(m->flags & PG_FICTITIOUS) != 0" can be deleted, but the rest should remain.

6198–6199

Same here as the first and second cases.

[kib]

Utilize empty pv_list of the md_dummy placeholder to avoid more conditionals.