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Differential D17340

Initialize kernel pmap resident_count and resident_wired.
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Authored by markj on Sep 27 2018, 3:41 PM.
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alc
kib
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rS339046: Count bootstrap data as resident in the kernel pmap.
Summary

kmem_bootstrap_free() may decrement these stats, and this occasionally
causes panics in INVARIANTS kernels when the resident count underflows.

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rS FreeBSD src repository - subversion
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Event Timeline

markj created this revision.Sep 27 2018, 3:41 PM
Harbormaster completed remote builds in B19843: Diff 48522.Sep 27 2018, 3:41 PM
markj added reviewers: alc, kib.Sep 27 2018, 3:42 PM
kib accepted this revision.Sep 27 2018, 4:20 PM
kib added inline comments.
sys/amd64/amd64/pmap.c
1123 ↗(On Diff #48522)

You can remove this blank line as well.

This revision is now accepted and ready to land.Sep 27 2018, 4:20 PM
markj updated this revision to Diff 48524.Sep 27 2018, 4:29 PM
markj marked an inline comment as done.
  • Remove blank line.
This revision now requires review to proceed.Sep 27 2018, 4:29 PM
Harbormaster completed remote builds in B19844: Diff 48524.Sep 27 2018, 4:29 PM
alc added a comment.Sep 27 2018, 5:02 PM

My recollection is that we do not set the wired bit in any of the page table entries created by create_pagetables() so we could wind up with a wired mapping count that exceeds the resident count.

markj added a comment.Sep 27 2018, 9:03 PM
In D17340#369770, @alc wrote:

My recollection is that we do not set the wired bit in any of the page table entries created by create_pagetables() so we could wind up with a wired mapping count that exceeds the resident count.

You're right. I was thinking of the page table pages.

markj updated this revision to Diff 48533.Sep 27 2018, 9:03 PM
  • Only initialize resident_count.
Harbormaster completed remote builds in B19850: Diff 48533.Sep 27 2018, 9:03 PM
markj added a comment.Oct 1 2018, 4:13 AM

Alan, did you have any other comments on this?

alc accepted this revision.Oct 1 2018, 4:33 AM
alc added inline comments.
sys/amd64/amd64/pmap.c
1145 ↗(On Diff #48533)

I would provide some motivation: "... resident in case any of this data is later unmapped (using pmap_remove()) and freed."

This revision is now accepted and ready to land.Oct 1 2018, 4:33 AM
Closed by commit rS339046: Count bootstrap data as resident in the kernel pmap. (authored by markj). · Explain WhyOct 1 2018, 2:48 PM
This revision was automatically updated to reflect the committed changes.
Herald added a subscriber: imp. · View Herald TranscriptOct 1 2018, 2:48 PM
markj marked an inline comment as done.Oct 1 2018, 2:48 PM
markj added inline comments.
sys/amd64/amd64/pmap.c
1145 ↗(On Diff #48533)

Sorry, I accidentally committed a stale version of the patch. Will fix. I also remembered after committing that we need the same change on i386. :(

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sys/
amd64/
amd64/
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head/sys/amd64/amd64/pmap.c

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