From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Rafael J. Wysocki" <rjw@sisk.pl>
Subject: Re: [RFC][PATCH 2/3] swsusp: Do not use page flags
Date: Tue, 13 Mar 2007 10:16:11 +0100
Message-ID: <200703131016.12935.rjw@sisk.pl>
References: <Pine.LNX.4.64.0702160212150.21862@schroedinger.engr.sgi.com>
	<200703041507.57122.rjw@sisk.pl> <45F62CD2.5030103@yahoo.com.au>
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To: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: linux-mm@kvack.org, Peter Zijlstra <a.p.zijlstra@chello.nl>, Pavel Machek <pavel@ucw.cz>, pm list <linux-pm@lists.osdl.org>, Johannes Berg <johannes@sipsolutions.net>, Christoph Lameter <clameter@engr.sgi.com>
List-Id: linux-pm@vger.kernel.org

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 wh=
ich
> > + *	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 conten=
ts
> > + *	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 >=3D end_pfn)
> > +		return;
> > +
> > +	if (!list_empty(&nosave_regions)) {
> > +		/* Try to extend the previous region (they should be sorted) */
> > +		region =3D list_entry(nosave_regions.prev,
> > +					struct nosave_region, list);
> > +		if (region->end_pfn =3D=3D start_pfn) {
> > +			region->end_pfn =3D end_pfn;
> > +			goto Report;
> > +		}
> > +	}
> > +	/* This allocation cannot fail */
> > +	region =3D alloc_bootmem_low(sizeof(struct nosave_region));
> > +	region->start_pfn =3D start_pfn;
> > +	region->end_pfn =3D 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