linux-kernel - Re: [PATCH v4 2/8] mm: Actually mark kernel page table pages

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Message-ID: <20250905182454.GN616306@nvidia.com>
Date: Fri, 5 Sep 2025 15:24:54 -0300
From: Jason Gunthorpe <jgg@...dia.com>
To: Lu Baolu <baolu.lu@...ux.intel.com>
Cc: Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
	Robin Murphy <robin.murphy@....com>,
	Kevin Tian <kevin.tian@...el.com>, Jann Horn <jannh@...gle.com>,
	Vasant Hegde <vasant.hegde@....com>,
	Dave Hansen <dave.hansen@...el.com>,
	Alistair Popple <apopple@...dia.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Uladzislau Rezki <urezki@...il.com>,
	Jean-Philippe Brucker <jean-philippe@...aro.org>,
	Andy Lutomirski <luto@...nel.org>, Yi Lai <yi1.lai@...el.com>,
	iommu@...ts.linux.dev, security@...nel.org,
	linux-kernel@...r.kernel.org,
	Dave Hansen <dave.hansen@...ux.intel.com>
Subject: Re: [PATCH v4 2/8] mm: Actually mark kernel page table pages

On Fri, Sep 05, 2025 at 01:50:57PM +0800, Lu Baolu wrote:
> From: Dave Hansen <dave.hansen@...ux.intel.com>
> 
> Now that the API is in place, mark kernel page table pages just
> after they are allocated. Unmark them just before they are freed.
> 
> Note: Unconditionally clearing the 'kernel' marking (via
> ptdesc_clear_kernel()) would be functionally identical to what
> is here. But having the if() makes it logically clear that this
> function can be used for kernel and non-kernel page tables.
> 
> Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>
> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
> ---
>  include/asm-generic/pgalloc.h | 18 ++++++++++++++++++
>  include/linux/mm.h            |  3 +++
>  2 files changed, 21 insertions(+)

Reviewed-by: Jason Gunthorpe <jgg@...dia.com>

Jason