linux-kernel - Re: [rfc] 2.6.19-rc1-git5: consolidation of file backed fault handlers

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Date:	Tue, 10 Oct 2006 10:53:22 +1000
From:	Nick Piggin <nickpiggin@...oo.com.au>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
CC:	Nick Piggin <npiggin@...e.de>, Hugh Dickins <hugh@...itas.com>,
	Linux Memory Management <linux-mm@...ck.org>,
	Andrew Morton <akpm@...l.org>, Jes Sorensen <jes@....com>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: [rfc] 2.6.19-rc1-git5: consolidation of file backed fault	handlers

Benjamin Herrenschmidt wrote:
> On Tue, 2006-10-10 at 06:57 +1000, Benjamin Herrenschmidt wrote:
> 
>>On Mon, 2006-10-09 at 18:12 +0200, Nick Piggin wrote:
>>
>>>OK, I've cleaned up and further improved this patchset, removed duplication
>>>while retaining legacy nopage handling, restored page_mkwrite to the ->fault
>>>path (due to lack of users upstream to attempt a conversion), converted the
>>>rest of the filesystems to use ->fault, restored MAP_POPULATE and population
>>>of remap_file_pages pages, replaced nopfn completely, and removed
>>>NOPAGE_REFAULT because that can be done easily with ->fault.
>>
>>What is the replacement ?
> 
> 
> I see ... so we now use PTR_ERR to return errors and NULL for refault...
> good for me but Andrew may want more...

The fault handler puts its desired return type into fault_data.type, and
returns NULL if there is no page to install, otherwise the pointer to
the struct page.

So you'd just set VM_FAULT_MINOR and return NULL, after doing the
vm_insert_pfn thing.

-- 
SUSE Labs, Novell Inc.
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