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Differential D32242

Drain a keg of a UMA_ZONE_NOFREE zone when it is destroyed.
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Authored by glebius on Oct 1 2021, 1:37 AM.
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imp

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markj
jeff
Summary

Looks like my (Jonathan's) change to GELI created a precedent
when an UMA_ZONE_NOFREE is being destroyed. Without this change
we are leaking zero items, but leaking pages:

Freed UMA keg (GELI buffers) was not empty (0 items). Lost 528 pages of memory.

Fixes: 2dbc9a388ee
PR: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=258787

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rS FreeBSD src repository - subversion
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Lint Passed
Unit
No Test Coverage
Build Status
Buildable 41872
Build 38760: arc lint + arc unit

Event Timeline

glebius created this revision.Oct 1 2021, 1:37 AM
Herald added a subscriber: imp. · View Herald TranscriptOct 1 2021, 1:37 AM
glebius requested review of this revision.Oct 1 2021, 1:37 AM
Harbormaster completed remote builds in B41872: Diff 96035.Oct 1 2021, 1:37 AM
markj added a comment.Oct 1 2021, 4:19 PM

From my reading, GELI sets _NOFREE to ensure that the reserve is not drained during a memory shortage. But UMA should not have done this in the first place, and it was fixed in commit f09cbea31a3ffc03361687cb39f264b6c8775212 . So does GELI still need to specify _NOFREE? If not, then my preferred solution is to drop the _NOFREE flag there. We should try hard to avoid adding new _NOFREE zones in general.

glebius added a comment.Oct 1 2021, 5:05 PM
In D32242#727897, @markj wrote:

From my reading, GELI sets _NOFREE to ensure that the reserve is not drained during a memory shortage. But UMA should not have done this in the first place, and it was fixed in commit f09cbea31a3ffc03361687cb39f264b6c8775212 . So does GELI still need to specify _NOFREE? If not, then my preferred solution is to drop the _NOFREE flag there. We should try hard to avoid adding new _NOFREE zones in general.

I believe you are 100% right. This flag we were carrying in our tree from the times that predate your fix.

glebius abandoned this revision.Oct 1 2021, 5:05 PM

The problem will be addressed differently.

markj mentioned this in D32702: Add UMA_ZONE_ALLFINI flag.Oct 28 2021, 1:45 PM

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sys/
vm/
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Diff 96035

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sys/vm/uma_core.c

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