linux-kernel - Re: [PATCH 4/4] mm: introduce and use VMA flag test helpers

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Message-ID: <20251030175421.GC1204670@ziepe.ca>
Date: Thu, 30 Oct 2025 14:54:21 -0300
From: Jason Gunthorpe <jgg@...pe.ca>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
	Muchun Song <muchun.song@...ux.dev>,
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Subject: Re: [PATCH 4/4] mm: introduce and use VMA flag test helpers

On Thu, Oct 30, 2025 at 02:03:02PM +0000, Lorenzo Stoakes wrote:

> Yeah, OK well your point has been made here, the compiler _is_ smart enough
> to save us here :)
> 
> Let's avoid this first word stuff altogether then.

I suggest to add some helpers to the general include/linux/bitmap.h
"subsystem" that lets it help do this:

#define BITMAP_OR_BITS(type, member, bit1, bit2, bit3) 

returns a type with the bitmap array member initialized to those bits

Then some other bitmap helpers that are doing the specific maths you
want..

* bitmap_and_eq(src1, src2, src3, nbits)  true if *src1 & *src2 == *src3
* bitmap_and_eq_zero(src1, src2, nbits)   true if *src1 & *src1 == 0
etc

Jason