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Date: Thu, 12 Jul 2012 21:58:15 +0200
From: Andrea Arcangeli <aarcange@redhat.com>
To: Rik van Riel <riel@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        Hillf Danton <dhillf@gmail.com>, Dan Smith <danms@us.ibm.com>,
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        Mike Galbraith <efault@gmx.de>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
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        Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: Re: [PATCH 36/40] autonuma: page_autonuma
Message-ID: <20120712195815.GQ20382@redhat.com>
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 <1340888180-15355-37-git-send-email-aarcange@redhat.com>
 <4FF14196.6040106@redhat.com>
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On Mon, Jul 02, 2012 at 02:37:10AM -0400, Rik van Riel wrote:
>  > +fail:
>  > +	printk(KERN_CRIT "allocation of page_autonuma failed.\n");
>  > +	printk(KERN_CRIT "please try the 'noautonuma' boot option\n");
>  > +	panic("Out of memory");
>  > +}
> 
> The system can run just fine without autonuma.
> 
> Would it make sense to simply disable autonuma at this point,
> but to try continue running?

BTW, the same would apply to mm/page_cgroup.c, but I think the idea
here is that something serious went wrong. Workaround with noautonuma
boot option is enough.

> 
> > @@ -700,8 +780,14 @@ static void free_section_usemap(struct page *memmap, unsigned long *usemap)
> >   	 */
> >   	if (PageSlab(usemap_page)) {
> >   		kfree(usemap);
> > -		if (memmap)
> > +		if (memmap) {
> >   			__kfree_section_memmap(memmap, PAGES_PER_SECTION);
> > +			if (!autonuma_impossible())
> > +				__kfree_section_page_autonuma(page_autonuma,
> > +							      PAGES_PER_SECTION);
> > +			else
> > +				BUG_ON(page_autonuma);
> 
> VM_BUG_ON ?
> 
> > +		if (!autonuma_impossible()) {
> > +			struct page *page_autonuma_page;
> > +			page_autonuma_page = virt_to_page(page_autonuma);
> > +			free_map_bootmem(page_autonuma_page, nr_pages);
> > +		} else
> > +			BUG_ON(page_autonuma);
> 
> ditto
> 
> >   	pgdat_resize_unlock(pgdat,&flags);
> >   	if (ret<= 0) {
> > +		if (!autonuma_impossible())
> > +			__kfree_section_page_autonuma(page_autonuma, nr_pages);
> > +		else
> > +			BUG_ON(page_autonuma);
> 
> VM_BUG_ON ?

These only run at the very boot stage, so performance is irrelevant
and it's safer to keep them on.

The rest was corrected.