From: Andrew Morton <akpm@digeo.com>
To: Russell King <rmk@arm.linux.org.uk>
Cc: Marcus Alanen <marcus@infa.abo.fi>,
maalanen@ra.abo.fi, linux-kernel@vger.kernel.org
Subject: Re: [patch, 2.5] __vmalloc allocates spurious page?
Date: Tue, 15 Oct 2002 15:21:18 -0700 [thread overview]
Message-ID: <3DAC94DE.BB6F4B4E@digeo.com> (raw)
In-Reply-To: 20021015230506.D7702@flint.arm.linux.org.uk
Russell King wrote:
>
> On Wed, Oct 16, 2002 at 12:58:12AM +0300, Marcus Alanen wrote:
> > >The unnecessary page is allocated only if size is initially a multiple
> > >of PAGE_SIZE, which sounds like a common case.
> >
> > Actually, size is already PAGE_ALIGNed, so we get the amount of pages
> > even easier.
>
> IIRC, back in the dim and distant past, the extra page was originally to
> catch things running off the end of their space (eg, modules). The
> idea was that modules (and other vmalloc'd areas) would be separated
> by one unmapped page.
>
> It looks like this got broken recently though.
Still there I think.
struct vm_struct *get_vm_area(unsigned long size, unsigned long flags)
{
...
/*
* We always allocate a guard page.
*/
size += PAGE_SIZE;
Marcus's patch looks reasonable.
prev parent reply other threads:[~2002-10-15 22:22 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-10-15 19:32 [patch, 2.5] __vmalloc allocates spurious page? Marcus Alanen
2002-10-15 21:58 ` Marcus Alanen
2002-10-15 22:05 ` Russell King
2002-10-15 22:11 ` William Lee Irwin III
2002-10-15 22:21 ` Andrew Morton [this message]
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