linux-kernel - Re: [PATCH v2 08/16] mm: add ability to take further action in vm_area

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Message-ID: <c7ae6643-f9bf-446f-a046-72ae2c8ff87c@lucifer.local>
Date: Fri, 12 Sep 2025 11:18:44 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: Reinette Chatre <reinette.chatre@...el.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
        Jonathan Corbet <corbet@....net>, Matthew Wilcox <willy@...radead.org>,
        Guo Ren <guoren@...nel.org>,
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Subject: Re: [PATCH v2 08/16] mm: add ability to take further action in
 vm_area_desc

On Thu, Sep 11, 2025 at 03:07:21PM -0700, Reinette Chatre wrote:
> Hi Lorenzo,
>
> On 9/10/25 1:22 PM, Lorenzo Stoakes wrote:
>
> ...
>
> > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> > index 4a441f78340d..ae6c7a0a18a7 100644
> > --- a/include/linux/mm_types.h
> > +++ b/include/linux/mm_types.h
> > @@ -770,6 +770,64 @@ struct pfnmap_track_ctx {
> >  };
> >  #endif
> >
> > +/* What action should be taken after an .mmap_prepare call is complete? */
> > +enum mmap_action_type {
> > +	MMAP_NOTHING,		 /* Mapping is complete, no further action. */
> > +	MMAP_REMAP_PFN,		 /* Remap PFN range based on desc->remap. */
> > +	MMAP_INSERT_MIXED,	 /* Mixed map based on desc->mixedmap. */
> > +	MMAP_INSERT_MIXED_PAGES, /* Mixed map based on desc->mixedmap_pages. */
> > +	MMAP_CUSTOM_ACTION,	 /* User-provided hook. */
> > +};
> > +
> > +struct mmap_action {
> > +	union {
> > +		/* Remap range. */
> > +		struct {
> > +			unsigned long addr;
> > +			unsigned long pfn;
> > +			unsigned long size;
> > +			pgprot_t pgprot;
> > +		} remap;
> > +		/* Insert mixed map. */
> > +		struct {
> > +			unsigned long addr;
> > +			unsigned long pfn;
> > +			unsigned long num_pages;
> > +		} mixedmap;
> > +		/* Insert specific mixed map pages. */
> > +		struct {
> > +			unsigned long addr;
> > +			struct page **pages;
> > +			unsigned long num_pages;
> > +			/* kfree pages on completion? */
> > +			bool kfree_pages :1;
> > +		} mixedmap_pages;
> > +		struct {
> > +			int (*action_hook)(struct vm_area_struct *vma);
> > +		} custom;
> > +	};
> > +	enum mmap_action_type type;
> > +
> > +	/*
> > +	 * If specified, this hook is invoked after the selected action has been
> > +	 * successfully completed. Not that the VMA write lock still held.
>
> A typo that may trip tired eyes: Not -> Note ? (perhaps also "is still held"?)
> (also in the duplicate changes to tools/testing/vma/vma_internal.h)

Yeah good catch! Will fix if respin :)

Cheers, Lorenzo