Evaluate the real size of the sblk_zone.

[kib]

Summary

This allows to not waste some small amount of memory, if available.

Submitted by: [e-mail]
PR: 221356

[alc]

I think that the change is fine, but it needs a comment. Otherwise, this is going to look awfully strange to someone who isn't familiar with the inner works of UMA.

[markj]

Makes sense to me.

[kib]

Add comment.

[alc]

sys/vm/swap_pager.c

546–548 ↗

(On Diff #33958)

"Often uma_zone_reserve_kva() cannot reserve exactly the requested size. Account for the difference when calculating swap_maxpages.