pmap_demote_{l2,pde}: never invalidate wired mappings
ClosedPublic
Actions

Authored by alc on Jul 20 2025, 12:37 AM.

Details

Reviewers

kib
markj
andrew
manu

Commits

rG7502c1f27082: pmap_demote_{l2,pde}: never invalidate wired mappings

Summary

Rather than demoting a superpage mapping that hasn't been accessed, we ordinarily invalidate it. However, if the mapping is wired, invalidation is problematic because the page fault to reinstantiate the mapping could sleep.

Diff Detail

Repository

rG FreeBSD src repository

Lint

Lint Not Applicable

Unit

Tests Not Applicable

Event Timeline

alc created this revision.Jul 20 2025, 12:37 AM

Herald added a reviewer: andrew. · View Herald TranscriptJul 20 2025, 12:37 AM

Herald added a reviewer: andrew. · View Herald Transcript

Herald added a reviewer: manu. · View Herald Transcript

Herald added a subscriber: emaste. · View Herald Transcript

alc requested review of this revision.Jul 20 2025, 12:37 AM

kib accepted this revision.Jul 20 2025, 1:02 AM

This revision is now accepted and ready to land.Jul 20 2025, 1:02 AM

I believe this makes D49442 unnecessary, at least as far as fixing the bug is concerned.

In D51431#1174792, @markj wrote:

I believe this makes D49442 unnecessary, at least as far as fixing the bug is concerned.

Yes.

Closed by commit rG7502c1f27082: pmap_demote_{l2,pde}: never invalidate wired mappings (authored by alc). · Explain WhyJul 23 2025, 6:03 PM

This revision was automatically updated to reflect the committed changes.

alc added a commit: rG7502c1f27082: pmap_demote_{l2,pde}: never invalidate wired mappings.

Herald added a subscriber: imp. · View Herald TranscriptJul 23 2025, 6:03 PM

Revision Contents
Changeset List

Path

Size

sys/

amd64/

pmap.c

21 lines

arm64/

pmap.c

24 lines

Diff 158955

View Options

sys/amd64/amd64/pmap.c