From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Laight <David.Laight@ACULAB.COM>
Subject: RE: [RFC PATCH 07/13] kernel/fork: Split and export 'mm_alloc' and
 'mm_init'
Date: Tue, 14 Mar 2017 10:18:03 +0000
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References: <20170313221415.9375-1-till.smejkal@gmail.com>
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From: Linuxppc-dev Till Smejkal
> Sent: 13 March 2017 22:14
> The only way until now to create a new memory map was via the exported
> function 'mm_alloc'. Unfortunately, this function not only allocates a ne=
w
> memory map, but also completely initializes it. However, with the
> introduction of first class virtual address spaces, some initialization
> steps done in 'mm_alloc' are not applicable to the memory maps needed for
> this feature and hence would lead to errors in the kernel code.
>=20
> Instead of introducing a new function that can allocate and initialize
> memory maps for first class virtual address spaces and potentially
> duplicate some code, I decided to split the mm_alloc function as well as
> the 'mm_init' function that it uses.
>=20
> Now there are four functions exported instead of only one. The new
> 'mm_alloc' function only allocates a new mm_struct and zeros it out. If o=
ne
> want to have the old behavior of mm_alloc one can use the newly introduce=
d
> function 'mm_alloc_and_setup' which not only allocates a new mm_struct bu=
t
> also fully initializes it.
...

That looks like bugs waiting to happen.
You need unchanged code to fail to compile.

	David


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