Hi,

On Wednesday, 10 of August 2005 23:50, Pavel Machek wrote:

Hi!

quoted

quoted

Swsusp is the main "is valid ram" user I have in mind here. It
wants to know whether or not it should save and restore the
memory of a given `struct page`.

Why can't it follow the rmap chain?

It is walking physical memory, not memory managment chains. I need
something like:

static int saveable(struct zone * zone, unsigned long * zone_pfn)
{
        unsigned long pfn = *zone_pfn + zone->zone_start_pfn;
        struct page * page;

        if (!pfn_valid(pfn))
                return 0;

        page = pfn_to_page(pfn);
        BUG_ON(PageReserved(page) && PageNosave(page));
        if (PageNosave(page))
                return 0;
        if (PageReserved(page) && pfn_is_nosave(pfn)) {

This only is a trick to avoid calling pfn_is_nosave(pfn) for every single page
that is neither PageNosave nor PageNosaveFree, isn't it?

                pr_debug("[nosave pfn 0x%lx]", pfn);
                return 0;
        }
        if (PageNosaveFree(page))
                return 0;

        return 1;
}

IMO it is safe to drop PageReserved from this function completely, which is
done in the following (experimental) patch (tested on x86-64).

Greets,
Rafael


Signed-off-by: Rafael J. Wysocki <redacted>

Index: linux-2.6.13-rc5-mm1/kernel/power/swsusp.c
===================================================================

--- linux-2.6.13-rc5-mm1.orig/kernel/power/swsusp.c
+++ linux-2.6.13-rc5-mm1/kernel/power/swsusp.c

@@ -674,15 +674,14 @@ static int saveable(struct zone * zone, 
 		return 0;
 
 	page = pfn_to_page(pfn);
-	BUG_ON(PageReserved(page) && PageNosave(page));
 	if (PageNosave(page))
 		return 0;
-	if (PageReserved(page) && pfn_is_nosave(pfn)) {
-		pr_debug("[nosave pfn 0x%lx]", pfn);
-		return 0;
-	}
 	if (PageNosaveFree(page))
 		return 0;
+	if (pfn_is_nosave(pfn)) {
+		pr_debug("  [nosave pfn 0x%lx]\n", pfn);
+		return 0;
+	}
 
 	return 1;
 }
 

-- 
- Would you tell me, please, which way I ought to go from here?
- That depends a good deal on where you want to get to.
		-- Lewis Carroll "Alice's Adventures in Wonderland"
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