linux-kernel - Re: [PATCH 01/32] mm, gup: introduce concept of "foreign" get_user

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Message-ID: <568BA039.4060901@suse.cz>
Date:	Tue, 5 Jan 2016 11:51:37 +0100
From:	Vlastimil Babka <vbabka@...e.cz>
To:	Dave Hansen <dave@...1.net>, linux-kernel@...r.kernel.org
Cc:	linux-mm@...ck.org, x86@...nel.org, dave.hansen@...ux.intel.com,
	akpm@...ux-foundation.org, kirill.shutemov@...ux.intel.com,
	aarcange@...hat.com, n-horiguchi@...jp.nec.com
Subject: Re: [PATCH 01/32] mm, gup: introduce concept of "foreign"
 get_user_pages()

On 12/14/2015 08:05 PM, Dave Hansen wrote:
> From: Dave Hansen <dave.hansen@...ux.intel.com>
>
> For protection keys, we need to understand whether protections
> should be enforced in software or not.  In general, we enforce
> protections when working on our own task, but not when on others.
> We call these "current" and "foreign" operations.
>
> This introduces two new get_user_pages() variants:
>
> 	get_current_user_pages()
> 	get_foreign_user_pages()
>
> get_current_user_pages() is a drop-in replacement for when
> get_user_pages() was called with (current, current->mm, ...) as
> arguments.  Using it makes a few of the call sites look a bit
> nicer.
>
> get_foreign_user_pages() is a replacement for when
> get_user_pages() is called on non-current tsk/mm.
>
> We leave a stub get_user_pages() around with a __deprecated
> warning.

Changelog doesn't mention that get_user_pages_unlocked() is also changed 
to be effectively get_current_user_pages_unlocked(). It's a bit 
non-obvious and the inconsistent naming is unfortunate, but I can see 
how get_current_user_pages_unlocked() would be too long, and just 
deleting the parameters from get_user_pages() would be too large and 
intrusive. But please mention this in changelog?

Thanks.

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