From: Arjan van de Ven <arjan@infradead.org>
To: Mohamed El Dawy <msdawy@gmail.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Is the address space of a process continous
Date: Sun, 04 Dec 2005 22:46:29 +0100 [thread overview]
Message-ID: <1133732789.5188.65.camel@laptopd505.fenrus.org> (raw)
In-Reply-To: <afd776760512041337l40a1879drb8b0b526100791a8@mail.gmail.com>
On Sun, 2005-12-04 at 15:37 -0600, Mohamed El Dawy wrote:
> Hi,
> I have a question. In the vma_memory_address struct, there are 2
> fields "vm_start" and "vm_end". I was wondering, does the process
> address space include all addresses between those 2 addresses? or
> could there be holes inside this range?
>
> The main reason I am asking is because I tried to call __follow_page()
> on some of those addresses and got NULL as a result. I am not sure if
> this is a hole, or just a problem with my code!
the kernel does this on demand; eg
user mmaps a range
user touches (read or writes) part of that range
each time the user gets to a page that wasn't touched/used before, the
kernel takes a fault and fills in the address.
if you get nulls it's just pages that haven't been used yet.
prev parent reply other threads:[~2005-12-04 21:46 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-12-04 21:37 Mohamed El Dawy
2005-12-04 21:46 ` Arjan van de Ven [this message]
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