Re: [Patch] memory unplug v3 [3/4] page removal

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

On Tue, 22 May 2007 11:52:11 -0700 (PDT)
Christoph Lameter <clameter@sgi.com> wrote:

> On Tue, 22 May 2007, KAMEZAWA Hiroyuki wrote:
> 
> > +static int
> > +do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
> > +{
> > +	unsigned long pfn;
> > +	struct page *page;
> > +	int move_pages = NR_OFFLINE_AT_ONCE_PAGES;
> > +	int not_managed = 0;
> > +	int ret = 0;
> > +	LIST_HEAD(source);
> > +
> > +	for (pfn = start_pfn; pfn < end_pfn && move_pages > 0; pfn++) {
> > +		if (!pfn_valid(pfn))
> > +			continue;
> > +		page = pfn_to_page(pfn);
> > +		/* page is isolated or being freed ? */
> > +		if ((page_count(page) == 0) || PageReserved(page))
> > +			continue;
> 
> The check above is not necessary. A Page count = 0 page is not on the LRU 
> neither is a Reserved page.

Ah, ok. but I'm now treating error in isolate_lru_page() as fatal.
This code avoid that isolate_lru_page() returns error by !PageLRU().
I'll consider again this part.

> > +	/* this function returns # of failed pages */
> > +	ret = migrate_pages_nocontext(&source, hotremove_migrate_alloc, 0);
> 
> You have no context so the last parameter should be 1?
>
migrate_pages_noccontest()'s 3rd param is equal to migrate_pages()'s 3rd param 'private'.


-Kame


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