Date: Fri, 11 Nov 2005 17:43:09 -0800
From: Andrew Morton <akpm@osdl.org>
To: Badari Pulavarty <pbadari@us.ibm.com>
Cc: andrea@suse.de, linux-kernel@vger.kernel.org, hugh@veritas.com,
       dvhltc@us.ibm.com, linux-mm@kvack.org, blaisorblade@yahoo.it,
       jdike@addtoit.com
Subject: Re: [PATCH] 2.6.14 patch for supporting madvise(MADV_REMOVE)
Message-Id: <20051111174309.5d544de4.akpm@osdl.org>
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Badari Pulavarty <pbadari@us.ibm.com> wrote:
>
> > Why does madvise_remove() have an explicit check for swapper_space?
> 
> I really don't remember (I yanked code from some other kernel routine
> vmtruncate()).

I don't see such a thing anywhere.  vmtruncate() has the IS_SWAPFILE()
test, which I guess vmtruncate_range() ought to have too, for
future-safety.

Logically, vmtruncate() should just be a special case of vmtruncate_range().
But it's not - ugly, but hard to do anything about (need to implement
->truncate_range in all filesystems, but "know" which ones only support
->truncate_range() at eof).

> 
> > In your testing, how are you determining that the code is successfully
> > removing the correct number of pages, from the correct file offset?
> 
> I verified with test programs, added debug printk + looked through live
> "crash" session + verified with UML testcases.

OK, well please be sure to test it on 32-bit and 64-bit, operating in three
ranges of the file: <2G, 2G-4G amd >4G.

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