linux-kernel - Re: vm_ops.page_mkwrite() fails with vmalloc on 2.6.23

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Message-ID: <45a44e480711010102s6ef51f67wff4a796deab0910b@mail.gmail.com>
Date:	Thu, 1 Nov 2007 04:02:44 -0400
From:	"Jaya Kumar" <jayakumar.lkml@...il.com>
To:	"Hugh Dickins" <hugh@...itas.com>
Cc:	"Peter Zijlstra" <a.p.zijlstra@...llo.nl>,
	"Andrew Morton" <akpm@...ux-foundation.org>, stefani@...bold.net,
	linux-kernel@...r.kernel.org,
	"David Howells" <dhowells@...hat.com>, linux-mm@...ck.org
Subject: Re: vm_ops.page_mkwrite() fails with vmalloc on 2.6.23

On Oct 30, 2007 11:47 AM, Hugh Dickins <hugh@...itas.com> wrote:
>
> I don't understand why you suggested an anon_vma, nor why Jaya is
> suggesting a private list.  All vmas mapping /dev/fb0 will be kept
> in the prio_tree rooted in its struct address_space (__vma_link_file
> in mm/mmap.c).  And page_mkclean gets page_mkclean_file to walk that
> very tree.  The missing part is just the setting of page->mapping to
> point to that struct address_space (and clearing it before finally
> freeing the pages), and the setting of page->index as you described.
> Isn't it?

Oops, sorry that I missed that. Now I understand. I think:

page->mapping = vma->vm_file->f_mapping
page->index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff

at nopage time and then before the driver vfrees, I'll clear mapping
for all those pages.

Thanks,
jaya
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