linux-kernel - Re: [05/17] vunmap: return page array

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Date:	Wed, 19 Sep 2007 17:05:59 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Christoph Lameter <clameter@....com>
Cc:	Christoph Hellwig <hch@....de>, Mel Gorman <mel@...net.ie>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	David Chinner <dgc@....com>, Jens Axboe <jens.axboe@...cle.com>
Subject: Re: [05/17] vunmap: return page array

On Tue, 18 Sep 2007 20:36:10 -0700
Christoph Lameter <clameter@....com> wrote:

> Make vunmap return the page array that was used at vmap. This is useful
> if one has no structures to track the page array but simply stores the
> virtual address somewhere. The disposition of the page array can be
> decided upon after vunmap. vfree() may now also be used instead of
> vunmap which will release the page array after vunmap'ping it.
> 
> Signed-off-by: Christoph Lameter <clameter@....com>
> 

Hmm, I don't like returning array which someone allocated in past and forgot.
And, area->page[] array under vmalloc() is allocated as following (in -rc6-mm1)
==
       if (array_size > PAGE_SIZE) {
                pages = __vmalloc_node(array_size, gfp_mask | __GFP_ZERO,
                                        PAGE_KERNEL, node);
                area->flags |= VM_VPAGES;
        } else {
                pages = kmalloc_node(array_size,
                                (gfp_mask & GFP_RECLAIM_MASK) | __GFP_ZERO,
                                node);
        }
==
A bit complicating.

At least, please add comments "How to free page-array returned by vummap"

Thanks,
-Kame

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