Handle trashed queue pointers in vm_page_acquire_unlocked().
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Authored by markj on Apr 17 2020, 5:15 PM.

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kib
alc
jeff

Commits

rS360122: Handle trashed queue pointers in vm_page_acquire_unlocked().

Summary

vm_page_acquire_unlocked() relies heavily on type-stability of vm_page
structures, and assumes that the listq linkage pointers always point to
a vm_page or are NULL. QUEUE_MACRO_DEBUG_TRASH breaks that assumption.

Reported by: pho

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No Test Coverage

Build Status

Buildable 30562
Build 28307: arc lint + arc unit

Event Timeline

markj created this revision.Apr 17 2020, 5:15 PM

Harbormaster completed remote builds in B30562: Diff 70701.Apr 17 2020, 5:15 PM

markj edited the summary of this revision. (Show Details)Apr 17 2020, 5:18 PM

markj added reviewers: kib, alc, jeff.

Isn't it too fragile still ? What if prev->q reused for something yet again ?

This revision is now accepted and ready to land.Apr 17 2020, 11:49 PM

In D24472#538433, @kib wrote:

Isn't it too fragile still ? What if prev->q reused for something yet again ?

That is handled by the subsequent checks, if I understood your question correctly.

In D24472#538438, @markj wrote:

In D24472#538433, @kib wrote:

Isn't it too fragile still ? What if prev->q reused for something yet again ?

That is handled by the subsequent checks, if I understood your question correctly.

I mean that there were attempts to reuse m->q for pages not in the object queue, and there probably would be more. I believe it is somewhat mitigated by the requirement that prev is either busy or wired, this is why I agreed with the proposed patch.

Closed by commit rS360122: Handle trashed queue pointers in vm_page_acquire_unlocked(). (authored by markj). · Explain WhyApr 20 2020, 2:45 PM

This revision was automatically updated to reflect the committed changes.

markj added a commit: rS360122: Handle trashed queue pointers in vm_page_acquire_unlocked()..

Herald added a subscriber: imp. · View Herald TranscriptApr 20 2020, 2:45 PM