linux-kernel - [PATCH v4 0/4] Convert 64-bit x86/mm/pat to ptdescs

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-next>] [day] [month] [year] [list]

Message-ID: <20260205013527.322157-1-vishal.moola@gmail.com>
Date: Wed,  4 Feb 2026 17:35:23 -0800
From: "Vishal Moola (Oracle)" <vishal.moola@...il.com>
To: linux-kernel@...r.kernel.org,
	linux-mm@...ck.org,
	x86@...nel.org,
	"Mike Rapoport (Microsoft)" <rppt@...nel.org>,
	Dave Hansen <dave.hansen@...ux.intel.com>
Cc: akpm@...ux-foundation.org,
	"Matthew Wilcox (Oracle)" <willy@...radead.org>,
	Andy Lutomirski <luto@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	"Vishal Moola (Oracle)" <vishal.moola@...il.com>
Subject: [PATCH v4 0/4] Convert 64-bit x86/mm/pat to ptdescs

x86/mm/pat should be using ptdescs. One line has already been
converted to pagetable_free(), while the allocation sites use
get_free_pages(). This causes issues separately allocating ptdescs
from struct page.

The first patch introduces new ptdesc apis that operate on addresses.
These are like get_free_pages() and free_pages() helper functions.

The remaining patches convert the allocation/free sites to use ptdescs. In
the short term, this helps enable Matthew's work to allocate frozen
pagetables[1]. And in the long term, this will help us cleanly split
ptdesc allocations from struct page[2].

The pgd_list should also be using ptdescs (for 32bit in this file). This
can be done in a different patchset since there's other users of pgd_list
that still need to be converted.

[1] https://lore.kernel.org/linux-mm/20251113140448.1814860-1-willy@infradead.org/
[2] https://lore.kernel.org/linux-mm/20251020001652.2116669-1-willy@infradead.org/

------

I've also tested this on a tree that separately allocates ptdescs. That
didn't find any lingering alloc/free issues.

Based on current mm-new.

v4:
  - Added new ptdesc apis
  - Also renamed the pte/pmd free functions as well
  - Explained reasoning for renaming functions in the commit logs
  - Updated the cover-letter

v3 link:
https://lore.kernel.org/linux-mm/20260202172005.683870-1-vishal.moola@gmail.com/

Vishal Moola (Oracle) (4):
  mm: Add address apis for ptdescs
  x86/mm/pat: Convert pte code to use ptdescs
  x86/mm/pat: Convert pmd code to use ptdescs
  x86/mm/pat: Convert split_large_page() to use ptdescs

 arch/x86/mm/pat/set_memory.c | 49 ++++++++++++++++++------------------
 include/linux/mm.h           |  4 +++
 mm/memory.c                  | 34 +++++++++++++++++++++++++
 3 files changed, 63 insertions(+), 24 deletions(-)

-- 
2.52.0