Historic Hibernation Issue
 

I have Slackware64-current on a twin core laptop with 6G ram.
Memory usage is light. I had a problem with hibernation and fixed the problem, and want to document it for posterity, because it's soo weird.

I never normally hibernate. But there's a few spurious undocumented key combinations that if pressed can start a hibernation. The box would appear to go off fine. It would boot a kernel, restore, wait a sec, then shut down and power off. That was the problem. It really was a case of "Do not adjust your set."
I would restart, promise I'd fix it, but never did.

It pulled a hibernate today. In the 'shutdown' phase of the hibernate, I noticed an error. It told me that I was lacking /usr/lib64/firefox-57.0??? I'm running firefox 68.0

On a hunch, I removed swap, zeroed it, made a new swap (same partition) and remounted it. Hibernate now works fine. Firefox-57.0 must have been about 2016? So a few things dawned on me

1. I mustn't have used any swap space in a long time.
2. This box isn't rewriting the hibernate image if it looks like there's a valid swap file there. I don't know if that's peculiar to this box, or a possible wider issue. It has endured more than 1 upgrade & 1 new install, and a second OS.
3. There happened to be a valid looking swap file there since 2016 which I wiped today.

I'd love to know if it's a crazy one-off, or something else.

How's it SOLVED?

The "valid" hibernation image from 2016 was zeroed, prompting a rewrite. I would hope hibernate images woule be rewritten more often; I thought it was every time, but someone is obviously saving cpu cycles.

/Later

I've since discovered that the whole shutdown mode of a hibernation has changed, indicating to me that it wasn't probably wasn't writing an image at all. Now it stays in X, sits there for 4-5 seconds, then turns all the lights off and is gone. Because I hadn't hibernated in so long, I didn't cop that my hibernate pattern didn't look right.