linux-kernel - Re: [PATCH 36/40] autonuma: page

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Message-ID: <20120712195815.GQ20382@redhat.com>
Date:	Thu, 12 Jul 2012 21:58:15 +0200
From:	Andrea Arcangeli <aarcange@...hat.com>
To:	Rik van Riel <riel@...hat.com>
Cc:	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Hillf Danton <dhillf@...il.com>, Dan Smith <danms@...ibm.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...e.hu>, Paul Turner <pjt@...gle.com>,
	Suresh Siddha <suresh.b.siddha@...el.com>,
	Mike Galbraith <efault@....de>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Lai Jiangshan <laijs@...fujitsu.com>,
	Bharata B Rao <bharata.rao@...il.com>,
	Lee Schermerhorn <Lee.Schermerhorn@...com>,
	Johannes Weiner <hannes@...xchg.org>,
	Srivatsa Vaddagiri <vatsa@...ux.vnet.ibm.com>,
	Christoph Lameter <cl@...ux.com>,
	Alex Shi <alex.shi@...el.com>,
	Mauricio Faria de Oliveira <mauricfo@...ux.vnet.ibm.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Don Morris <don.morris@...com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>
Subject: Re: [PATCH 36/40] autonuma: page_autonuma

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.
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