netdev - Re: [PATCH net-next] net: use bigger pages in __netdev_alloc

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Date:	Wed, 26 Sep 2012 15:57:31 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Benjamin LaHaise <bcrl@...ck.org>
Cc:	David Miller <davem@...emloft.net>,
	netdev <netdev@...r.kernel.org>,
	Alexander Duyck <alexander.h.duyck@...el.com>
Subject: Re: [PATCH net-next] net: use bigger pages in __netdev_alloc_frag

On Wed, 2012-09-26 at 09:11 -0400, Benjamin LaHaise wrote:
> Hello Eric,
> 
> On Wed, Sep 26, 2012 at 11:06:42AM +0200, Eric Dumazet wrote:
> > +	int order;
> ...
> > +		for (order = NETDEV_FRAG_PAGE_MAX_ORDER; ;) {
> > +			gfp_t gfp = gfp_mask;
> > +
> > +			if (order)
> > +				gfp |= __GFP_COMP | __GFP_NOWARN;
> > +			nc->frag.page = alloc_pages(gfp, order);
> > +			if (likely(nc->frag.page))
> > +				break;
> > +			if (--order <= 0)
> > +				goto end;
> > +		}
> 
> I think you probably intended the last if to be "if (--order < 0)", as 
> otherwise the alloc will never be attempted with an order 0 page, which 
> could harm systems suffering from extreme memory fragmentation.  Cheers,
> 

Indeed, thanks Ben !


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