Re: [PATCH 1/1] mmap.c: find_vma: remove if(mm) check

From: Andrew Morton
Date: Tue Mar 27 2012 - 18:12:38 EST


On Mon, 26 Mar 2012 19:49:27 -0400
Kautuk Consul <consul.kautuk@xxxxxxxxx> wrote:

> find_vma is called from kernel code where it is absolutely
> sure that the mm_struct arg being passed to it is non-NULL.
>
> Remove the if(mm) check.

It's odd that the if(mm) test exists - I wonder why it was originally
added. My repo only goes back ten years, and it's there in 2.4.18.

Any code which calls find_vma() without an mm is surely pretty busted?


Still, I think I'd prefer to do

if (WARN_ON_ONCE(!mm))
return NULL;

then let that bake for a kernel release, just to find out if we have a
weird caller out there, such as a function which is called by both user
threads and by kernel threads.
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