linux-kernel - Re: [PATCH 2/2] print vmalloc() state after allocation failures

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Date:	Fri, 08 Apr 2011 13:47:14 -0700
From:	Dave Hansen <dave@...ux.vnet.ibm.com>
To:	David Rientjes <rientjes@...gle.com>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Johannes Weiner <hannes@...xchg.org>
Subject: Re: [PATCH 2/2] print vmalloc() state after allocation failures

On Fri, 2011-04-08 at 13:39 -0700, David Rientjes wrote:
> On Fri, 8 Apr 2011, Dave Hansen wrote:
> > This patch will print out messages that look like this:
> > 
> > [   30.040774] bash: vmalloc failure allocating after 0 / 73728 bytes
> > 
> 
> Either the changelog or the patch is still wrong because the format of 
> this string is inconsistent.

Yeah, ya caught me. :)
> > diff -puN mm/vmalloc.c~vmalloc-warn mm/vmalloc.c
> > --- linux-2.6.git/mm/vmalloc.c~vmalloc-warn	2011-04-08 09:36:05.877020199 -0700
> > +++ linux-2.6.git-dave/mm/vmalloc.c	2011-04-08 09:38:00.373093593 -0700
> > @@ -1534,6 +1534,7 @@ static void *__vmalloc_node(unsigned lon
> >  static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
> >  				 pgprot_t prot, int node, void *caller)
> >  {
> > +	int order = 0;
> 
> Unnecessary, we can continue to hardcode the 0, vmalloc isn't going to use 
> higher order allocs (it's there to avoid such things!).

The only reason I did that was to keep the printk from looking like
this:

> > +	nopage_warning(gfp_mask, 0,  "vmalloc: allocation failure, "
> > +			"allocated %ld of %ld bytes\n",
> > +			(area->nr_pages*PAGE_SIZE), area->size);

The order is pretty darn obvious in the direct allocator calls, but I
liked having it named where it wasn't as obvious.

> >  	struct page **pages;
> >  	unsigned int nr_pages, array_size, i;
> >  	gfp_t nested_gfp = (gfp_mask & GFP_RECLAIM_MASK) | __GFP_ZERO;
> > @@ -1560,11 +1561,12 @@ static void *__vmalloc_area_node(struct 
> >  
> >  	for (i = 0; i < area->nr_pages; i++) {
> >  		struct page *page;
> > +		gfp_t tmp_mask = gfp_mask | __GFP_NOWARN;
> 
> I think it would be better to just do away with this as well and just 
> hardwire the __GFP_NOWARN directly into the two allocation calls.

I did it because hard-wiring it takes the alloc_pages_node() one over 80
columns.  I figured if I was going to add a line, I might as well keep
it pretty.

-- Dave

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