RFC swsusp: Do not use page flags (was: Re: Remove page flags for software suspend)

Quoted 22 lines · Nick Piggin

Quoted 8 lines · Rafael J. Wysocki

Quoted 6 lines · Christoph Lameter

Quoted 2 lines · Pavel Machek

I... actually do not like that patch. It adds code... at little or no benefit.

Quoted 8 lines

Quoted 3 lines

We are looking into saving page flags since we are running out. The two page flags used by software suspend are rarely needed and should be taken out of the flags. If you can do it a different way then please do.

As I have already said for a couple of times, I think we can and I'm going to do it, but right now I'm a bit busy with other things that I consider as more urgent.

I need one bit for lockless pagecache ;)

Anyway, I guess if you want something done you have to do it yourself.

Quoted 8 lines

This patch still needs work (and I don't know if it even works, because I can't make swsusp resume even on a vanilla kernel). But this is my WIP for removing swsusp page flags.

This patch adds a simple extent based nosave region tracker, and rearranges some of the snapshot code to be a bit simpler and more amenable to having dynamically allocated flags (they aren't actually dynamically allocated in this patch, however).

Thanks for the patch.

Probably I'd like to do some things in a different way, I'll think about that later today.

I hope I'll have a working patch that removes the "offending" page flags after the weekend.