From: Dave Hansen <dave.hansen@intel.com>
To: Kevin Brodsky <kevin.brodsky@arm.com>, linux-mm@kvack.org
Cc: Andrew Morton <akpm@linux-foundation.org>,
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Subject: Re: [PATCH 19/22] x86/tboot: mark tboot_mm as a kernel mm
Date: Tue, 14 Jul 2026 08:19:51 -0700 [thread overview]
Message-ID: <8acb01ac-0875-4816-8826-59e15b4e30b8@intel.com> (raw)
In-Reply-To: <20260714-remove_pgtable_cdtor-v1-19-44be8a7685d7@arm.com>
On 7/14/26 07:04, Kevin Brodsky wrote:
> tboot_mm is a kernel-owned address space used to build the
> identity map for tboot shutdown. Mark it with MMF_KERNEL so
> page table allocation and initialisation code treats its page tables
> as kernel page tables.
>
> Having marked tboot_mm as a kernel mm, we also need to convert
> pte_alloc_map() (user PTE) to pte_alloc_kernel() (kernel PTE), and
> drop the matching pte_unmap().
This makes me wonder whether MMF_KERNEL is the right way to mark these mms.
I think this series tries to cram too much into that one bit.
Using MMF_KERNEL to drive the page table accounting seems like a good
idea. It also seems like a good thing to make sure that those mm's don't
ever exit to userspace, for instance.
But I think it goes a step too far to say that all the special 'init_mm'
TLB flushing should also be common among all MMF_KERNEL mms.
My suggestion for now would be to just go after the page table
accounting alone. Don't mechanically replace mm==&mm_init checks.
next prev parent reply other threads:[~2026-07-14 15:19 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-14 14:03 [PATCH 00/22] Simplify special kernel page table handling Kevin Brodsky
2026-07-14 14:03 ` [PATCH 01/22] mm: drop unused __mm_flags_set_mask_bits_word() Kevin Brodsky
2026-07-14 14:03 ` [PATCH 02/22] mm: move mm_flags helpers to mm_types.h Kevin Brodsky
2026-07-14 14:03 ` [PATCH 03/22] mm: introduce MMF_KERNEL flag and set it for init_mm Kevin Brodsky
2026-07-14 14:47 ` Dave Hansen
2026-07-14 15:04 ` Lorenzo Stoakes (ARM)
2026-07-14 14:03 ` [PATCH 04/22] mm: use mm_is_kernel() in generic page table code Kevin Brodsky
2026-07-14 14:03 ` [PATCH 05/22] arm64: mm: use mm_is_kernel() for kernel mm checks Kevin Brodsky
2026-07-14 14:03 ` [PATCH 06/22] loongarch: mm: use mm_is_kernel() in switch_mm_irqs_off() Kevin Brodsky
2026-07-14 14:03 ` [PATCH 07/22] parisc: mm: use mm_is_kernel() for kernel mm checks Kevin Brodsky
2026-07-14 14:03 ` [PATCH 08/22] powerpc: " Kevin Brodsky
2026-07-14 14:03 ` [PATCH 09/22] s390: " Kevin Brodsky
2026-07-14 14:03 ` [PATCH 10/22] sparc: " Kevin Brodsky
2026-07-14 14:04 ` [PATCH 11/22] um: mm: use mm_is_kernel() in TLB sync Kevin Brodsky
2026-07-14 14:04 ` [PATCH 12/22] x86/mm: use mm_is_kernel() for kernel mm checks Kevin Brodsky
2026-07-14 15:09 ` Dave Hansen
2026-07-14 14:04 ` [PATCH 13/22] mm: account page table pages when allocated Kevin Brodsky
2026-07-14 14:04 ` [PATCH 14/22] mm: set page table page type " Kevin Brodsky
2026-07-14 15:16 ` Vishal Moola
2026-07-14 14:04 ` [PATCH 15/22] mm: only initialise pt_share_count for user pgtables Kevin Brodsky
2026-07-14 14:04 ` [PATCH 16/22] efi: mark efi_mm as a kernel mm Kevin Brodsky
2026-07-14 14:04 ` [PATCH 17/22] mm: pagewalk: drop redundant address check for kernel mm walks Kevin Brodsky
2026-07-14 14:04 ` [PATCH 18/22] arm64: mm: drop explicit mm_is_efi() check in contpte Kevin Brodsky
2026-07-14 14:04 ` [PATCH 19/22] x86/tboot: mark tboot_mm as a kernel mm Kevin Brodsky
2026-07-14 15:19 ` Dave Hansen [this message]
2026-07-14 14:04 ` [PATCH 20/22] arm64: mm: drop ctor/dtor calls for kernel page tables Kevin Brodsky
2026-07-14 14:04 ` [PATCH 21/22] arm: mm: drop ctor call " Kevin Brodsky
2026-07-14 14:04 ` [PATCH 22/22] riscv: mm: drop ctor/dtor calls " Kevin Brodsky
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