linux-kernel - Re: [PATCH 02/16] mm: introduce leaf entry type and use to simplify leaf entry logic

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Message-ID: <20251105172115.GQ1204670@ziepe.ca>
Date: Wed, 5 Nov 2025 13:21:15 -0400
From: Jason Gunthorpe <jgg@...pe.ca>
To: Gregory Price <gourry@...rry.net>
Cc: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Christian Borntraeger <borntraeger@...ux.ibm.com>,
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Subject: Re: [PATCH 02/16] mm: introduce leaf entry type and use to simplify
 leaf entry logic

On Wed, Nov 05, 2025 at 09:42:24AM -0500, Gregory Price wrote:
> On Mon, Nov 03, 2025 at 12:31:43PM +0000, Lorenzo Stoakes wrote:
> > +typedef swp_entry_t leaf_entry_t;
> > +
> > +#ifdef CONFIG_MMU
> > +
> > +/* Temporary until swp_entry_t eliminated. */
> > +#define LEAF_TYPE_SHIFT SWP_TYPE_SHIFT
> > +
> > +enum leaf_entry_type {
> > +	/* Fundamental types. */
> > +	LEAFENT_NONE,
> > +	LEAFENT_SWAP,
> > +	/* Migration types. */
> > +	LEAFENT_MIGRATION_READ,
> > +	LEAFENT_MIGRATION_READ_EXCLUSIVE,
> > +	LEAFENT_MIGRATION_WRITE,
> > +	/* Device types. */
> > +	LEAFENT_DEVICE_PRIVATE_READ,
> > +	LEAFENT_DEVICE_PRIVATE_WRITE,
> > +	LEAFENT_DEVICE_EXCLUSIVE,
> > +	/* H/W posion types. */
> > +	LEAFENT_HWPOISON,
> > +	/* Marker types. */
> > +	LEAFENT_MARKER,
> > +};
> > +
> 
> Have been browsing the patch set again, will get around a deeper review,
> but just wanted to say this is a thing of beauty :]

+1 I thought the same thing. So much clearer what is going on here,
and I didn't realize we had so many types already..

Jason