From: "Jared Hulbert" <jaredeh@gmail.com>
To: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Andrew Morton <akpm@linux-foundation.org>,
npiggin@nick.local0.net,
Linus Torvalds <torvalds@linux-foundation.org>,
Carsten Otte <cotte@de.ibm.com>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
linux-mm@kvack.org
Subject: Re: [patch 0/7] [rfc] VM_MIXEDMAP, pte_special, xip work
Date: Wed, 12 Mar 2008 09:40:37 -0700 [thread overview]
Message-ID: <6934efce0803120940x49707de7icb66d9cb6950ea86@mail.gmail.com> (raw)
In-Reply-To: <200803121633.34539.nickpiggin@yahoo.com.au>
> 2. VM_MIXEDMAP allows us to support mappings where you actually do want
> to refcount _some_ pages in the mapping, but not others. I haven't
> actually seen his code, but I understand Jared requires this for his
> filesystem that can migrate pages between RAM and XIP/NVRAM
> transparently. Obviously the filesystem isn't finished yet, but
> Jared is relying on these changes for it to work.
So the filesystem I'm working on right now isn't that cool... It's
just a readonly XIP filesystem. But it does need VM_MIXEDMAP.
The problem was that VM_PFNMAP required pfn mapped pages to be
contiguous. My filesystem wants to allow a mixed of struct page and
pfn mapped pages within a given vma. VM_MIXEDMAP allows that to
happen.
But VM_MIXEDMAP is one of those foundation pieces that will allow us
to move on and do the cool migrate from RAM to NVM magic. You can't
transparently migrate pages when you are tied down to the VM_PFNMAP
rules. It'd be more like migrating vma chunks, yuck.
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next prev parent reply other threads:[~2008-03-12 16:40 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-03-11 10:46 [patch 0/7] [rfc] VM_MIXEDMAP, pte_special, xip work npiggin
2008-03-11 10:46 ` [patch 1/7] mm: introduce VM_MIXEDMAP npiggin, Jared Hulbert
2008-03-11 10:46 ` [patch 2/7] mm: introduce pte_special pte bit npiggin
2008-03-11 10:46 ` [patch 3/7] mm: add vm_insert_mixed npiggin
2008-03-11 10:46 ` [patch 4/7] Alter the block device ->direct_access() API to work with the new get_xip_mem() API (that requires both kaddr and pfn are returned) npiggin
2008-03-11 10:46 ` [patch 5/7] xip: support non-struct page backed memory npiggin
2008-03-11 11:44 ` [patch 0/7] [rfc] VM_MIXEDMAP, pte_special, xip work Nick Piggin
2008-03-11 21:12 ` Jared Hulbert
2008-03-11 23:21 ` Nick Piggin
2008-03-12 4:35 ` Andrew Morton
2008-03-12 5:33 ` Nick Piggin
2008-03-12 8:46 ` Martin Schwidefsky
2008-03-12 16:40 ` Jared Hulbert [this message]
2008-03-12 17:10 ` Jared Hulbert
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