Differential D20758

Add a return value to vm_page_remove().
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Authored by markj on Jun 25 2019, 4:02 PM.

Details

Reviewers

alc
dougm
kib

Commits

rS349432: Add a return value to vm_page_remove().

Summary

This is a small piece of D20486. In that revision we count the object's
reference in the page's ref_count field, and atomically decrement that
reference and check for others.

All callers except for vm_page_free_prep() must provide a page contained
in an object, so move the m->object != NULL check out of
vm_page_remove().

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Build Status

Buildable 25036
Build 23750: arc lint + arc unit

Event Timeline

markj created this revision.Jun 25 2019, 4:02 PM

Harbormaster completed remote builds in B25036: Diff 59010.Jun 25 2019, 4:02 PM

markj added reviewers: alc, dougm, kib.Jun 25 2019, 4:04 PM

dougm added inline comments.Jun 25 2019, 4:31 PM

sys/vm/vm_page.c
1485	Before, object could have been NULL, evidently. Here, you depend on it being not NULL. Can you assert that somewhere?

markj added inline comments.Jun 25 2019, 4:36 PM

sys/vm/vm_page.c
1485	In general we don't add assertions for conditions which will unconditionally crash the kernel anyway. In particular, the VM_OBJECT_ASSERT_WLOCKED() above effectively provides the same assertion.