Re: Suspend2 Merge: e820 table support.

[Pavel Machek <pavel@ucw.cz>]

Hi!

> > > +#ifdef CONFIG_SOFTWARE_SUSPEND2
> > > +			/*
> > > +			 * Mark nosave pages
> > > +			 */
> > > +			if (addr >= (void *)&__nosave_begin && addr < (void *)&__nosave_end)
> > > +				SetPageNosave(mem_map+tmp);
> > > +		} else
> > > +			/*
> > > +			 * Non-RAM pages are always nosave
> > > +			 */
> > > +			SetPageNosave(mem_map+tmp);
> > > +#else
> > > +		}
> > > +#endif
> > > +	}
> > 
> > Current -mm code does something funny with Nosave; I'm not sure it
> > will not try to free them after resume. I have fix in my tree but it
> > is little tested.
> 
> Double negative: you think current mm may try to free Nosave pages after
> resume? I haven't updated to the latest -mm yet, but will see if I can
> try tomorrow.


Hmm, it also contains (saveable()):

        BUG_ON(PageReserved(page) && PageNosave(page));

..but that should be easy to kill. I'd be worried about this function:

static void free_suspend_pagedir_zone(struct zone *zone, unsigned long
pagedir)
{
        unsigned long zone_pfn, pagedir_end, pagedir_pfn,
pagedir_end_pfn;
        pagedir_end = pagedir + (PAGE_SIZE << pagedir_order);
        pagedir_pfn = __pa(pagedir) >> PAGE_SHIFT;
        pagedir_end_pfn = __pa(pagedir_end) >> PAGE_SHIFT;
        for (zone_pfn = 0; zone_pfn < zone->spanned_pages; ++zone_pfn)
{
                struct page *page;
                unsigned long pfn = zone_pfn + zone->zone_start_pfn;
                if (!pfn_valid(pfn))
                        continue;
                page = pfn_to_page(pfn);
                if (!TestClearPageNosave(page))
                        continue;
                else if (pfn >= pagedir_pfn && pfn < pagedir_end_pfn)
                        continue;
                __free_page(page);
        }
}

I posted diff to get rid of it, but it did not get enough testing so
it is not in mainline.
								Pavel

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