uma: Avoid unmapping ranges in the direct map
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Authored by markj on Jan 1 2021, 10:22 PM.

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Reviewers

alc
kib

Commits

rG663de81f852f: uma: Avoid unmapping direct-mapped slabs

Summary

startup_alloc() uses pmap_map() to map slabs used for early allocations.
pmap_map() may ignore the hint address and simply return a range from
the direct map. In this case we must not unmap the range in
startup_free().

UMA uses bootstart and bootmem to track the range of KVA into which
slabs are mapped if the direct map is not used. Unmap a startup slab
only if it was mapped into that range.

Diff Detail

Repository

rG FreeBSD src repository

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Unit

Tests Not Applicable

Event Timeline

markj created this revision.Jan 1 2021, 10:22 PM

Herald added a subscriber: imp. · View Herald TranscriptJan 1 2021, 10:22 PM

markj requested review of this revision.Jan 1 2021, 10:22 PM

Harbormaster completed remote builds in B35846: Diff 81486.Jan 1 2021, 10:22 PM

markj added reviewers: alc, kib.Jan 1 2021, 10:22 PM

kib accepted this revision.Jan 1 2021, 10:31 PM

This revision is now accepted and ready to land.Jan 1 2021, 10:31 PM

alc accepted this revision.Jan 1 2021, 11:17 PM

alc added inline comments.

sys/vm/uma_core.c
1694–1700	I don't think that it is immediately obvious from this test that it exists so that we don't perform pmap_remove() on the direct map. Could you please add a comment explaining that here?