linux-kernel - Re: [PATCH v4 5/8] x86/mm: Use pagetable

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250905184115.GQ616306@nvidia.com>
Date: Fri, 5 Sep 2025 15:41:15 -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
Subject: Re: [PATCH v4 5/8] x86/mm: Use pagetable_free()

On Fri, Sep 05, 2025 at 01:51:00PM +0800, Lu Baolu wrote:
> The kernel's memory management subsystem provides a dedicated interface,
> pagetable_free(), for freeing page table pages. Updates two call sites to
> use pagetable_free() instead of the lower-level __free_page() or
> free_pages(). This improves code consistency and clarity, and ensures the
> correct freeing mechanism is used.
> 
> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
> ---
>  arch/x86/mm/init_64.c        | 2 +-
>  arch/x86/mm/pat/set_memory.c | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
> index 76e33bd7c556..86b4297c1984 100644
> --- a/arch/x86/mm/init_64.c
> +++ b/arch/x86/mm/init_64.c
> @@ -1013,7 +1013,7 @@ static void __meminit free_pagetable(struct page *page, int order)
>  		free_reserved_pages(page, nr_pages);
>  #endif
>  	} else {
> -		free_pages((unsigned long)page_address(page), order);
> +		pagetable_free(page_ptdesc(page));
>  	}
>  }

Er.. So if bootmem happens to be under the table and we happen to free
it due to memory hotplug we don't go through the SVA fixing path?

Seems wrong??

Bootmem still has a ptdesc and a usable linked list, right?

So maybe this should be redone into an arch hook in/around
__pagetable_free() and all the above frees just use the normal ptdesc
free path, including the SVA work queue?

Jason