Re: [RFC][PATCH 2/3] swsusp: Do not use page flags

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Tuesday, 13 March 2007 05:47, Nick Piggin wrote:
> Rafael J. Wysocki wrote:
> 
> >  }
> >  
> >  /**
> > + *	This structure represents a range of page frames the contents of which
> > + *	should not be saved during the suspend.
> > + */
> > +
> > +struct nosave_region {
> > +	struct list_head list;
> > +	unsigned long start_pfn;
> > +	unsigned long end_pfn;
> > +};
> > +
> > +static LIST_HEAD(nosave_regions);
> > +
> > +/**
> > + *	register_nosave_region - register a range of page frames the contents
> > + *	of which should not be saved during the suspend (to be used in the early
> > + *	initializatoion code)
> > + */
> > +
> > +void __init
> > +register_nosave_region(unsigned long start_pfn, unsigned long end_pfn)
> > +{
> > +	struct nosave_region *region;
> > +
> > +	if (start_pfn >= end_pfn)
> > +		return;
> > +
> > +	if (!list_empty(&nosave_regions)) {
> > +		/* Try to extend the previous region (they should be sorted) */
> > +		region = list_entry(nosave_regions.prev,
> > +					struct nosave_region, list);
> > +		if (region->end_pfn == start_pfn) {
> > +			region->end_pfn = end_pfn;
> > +			goto Report;
> > +		}
> > +	}
> > +	/* This allocation cannot fail */
> > +	region = alloc_bootmem_low(sizeof(struct nosave_region));
> > +	region->start_pfn = start_pfn;
> > +	region->end_pfn = end_pfn;
> > +	list_add_tail(&region->list, &nosave_regions);
> > + Report:
> > +	printk("swsusp: Registered nosave memory region: %016lx - %016lx\n",
> > +		start_pfn << PAGE_SHIFT, end_pfn << PAGE_SHIFT);
> > +}
> 
> 
> I wonder why you reimplemented this and put it in snapshot.c, rather than
> use my version which was nicely in its own file, had appropriate locking,
> etc.?

Well, the locking is not necessary and we only need a list for that.  Also,
mark_nosave_pages() refers to a function that's invisible outside snapshot.c
and I didn't think it was a good idea to separate mark_nosave_pages()
from register_nosave_region().

Greetings,
Rafael