linux-kernel - Re: Pagecache zeroing: zero_user_segment, zero_user_segments and zero

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Date:	Wed, 16 May 2007 14:52:05 +1000
From:	Nick Piggin <nickpiggin@...oo.com.au>
To:	Christoph Lameter <clameter@....com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org,
	Satyam Sharma <satyam.sharma@...il.com>,
	Nate Diller <nate.diller@...il.com>
Subject: Re: Pagecache zeroing: zero_user_segment, zero_user_segments and
 zero_user

Christoph Lameter wrote:
> On Tue, 15 May 2007, Andrew Morton wrote:
> 
> 
>>>   The functions above default to KM_USER0 which is also always used when
>>>   zero_user_page was called except in one single case. We open code that
>>>   single case to draw attention to the spot.
>>>
>>
>>Dunno.  fwiw, we decided to _not_ embed KM_USER0 in the callee: we have had
>>some pretty ghastly bugs in the past due to misuse of kmap slots so the
>>idea was to shove the decision into the caller's face, make them think
>>about what they're doing
> 
> 
> On the other hand non highmem platforms are burdened with always repeating
> the same KM_USER0 in every function call. Isnt it enough to know that 
> standard functions use KM_USER0 for their operations?

Couldn't that be filtered out inline?

-- 
SUSE Labs, Novell Inc.
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