linux-kernel - Re: [PATCH v5 09/16] kexec: enable KHO support for memory preservation

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Message-ID: <Z_Yxa7fTA70YEe84@kernel.org>
Date: Wed, 9 Apr 2025 11:35:55 +0300
From: Mike Rapoport <rppt@...nel.org>
To: Jason Gunthorpe <jgg@...dia.com>
Cc: Pratyush Yadav <ptyadav@...zon.de>,
	Changyuan Lyu <changyuanl@...gle.com>, linux-kernel@...r.kernel.org,
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Subject: Re: [PATCH v5 09/16] kexec: enable KHO support for memory
 preservation

On Thu, Apr 03, 2025 at 01:10:01PM -0300, Jason Gunthorpe wrote:
> On Thu, Apr 03, 2025 at 03:50:04PM +0000, Pratyush Yadav wrote:
> 
> > +struct kho_mem_track {
> > +	/* Points to L4 KHOMEM descriptor, each order gets its own table. */
> > +	struct xarray orders;
> > +};
> 
> I think it would be easy to add a 5th level and just use bits 63:57 as
> a 6 bit order. Then you don't need all this stuff either.

Even 4 levels won't work with 16K and 64K pages.
To use tables we'd need to scale the number of levels based on PAGE_SIZE.
 
> Jason

-- 
Sincerely yours,
Mike.