Subject: [PATCH 0/6] mm: Consolidate lazy MMU mode context

From: Alexander Gordeev <[email-masked]>
Date: Thu, 12 Jun 2025 19:36:07 +0200

Hi All,

Consolidate arch_enter|leave|flush_lazy_mmu_mode() context and protect
with a lock not only user, but also kernel mappings before entering
the lazy MMU mode.

For not fully preemptible (Real-Time) kernels that simplifies semantics -
while the mode is active the code should assume it is executing in atomic
context. That paves the way for cleanups, such as suggested for sparc and
powerpc and hopefully brings a bit more clarity in what labeled in commit
691ee97e1a9d ("mm: fix lazy mmu docs and usage") as "a bit of a mess (to
put it politely)".

The fully preemptible (Real-Time) kernels could probably also be brought
into the fold, but I am not sure about implications (to say at least).

This series is continuation of [1] and [2], with commit b6ea95a34cbd
("kasan: avoid sleepable page allocation from atomic context") already
upstream.

I dared to keep Nicholas Piggin R-b on patch 3, but dropped it from
patch 2 due to new bits.

Except the optional sparc (untested) and powerpc (complile-tested)
updates this series is a prerequisite for implementation of lazy MMU
mode on s390.

1. https://lore.kernel.org/linux-mm/[email-masked]/#r
2. https://lore.kernel.org/linux-mm/[email-masked]/#r

Thanks!

Alexander Gordeev (6):
  mm: Cleanup apply_to_pte_range() routine
  mm: Lock kernel page tables before entering lazy MMU mode
  mm/debug: Detect wrong arch_enter_lazy_mmu_mode() contexts
  sparc/mm: Do not disable preemption in lazy MMU mode
  powerpc/64s: Do not disable preemption in lazy MMU mode
  powerpc/64s: Do not re-activate batched TLB flush

 .../include/asm/book3s/64/tlbflush-hash.h     | 13 ++++----
 arch/powerpc/include/asm/thread_info.h        |  2 --
 arch/powerpc/kernel/process.c                 | 25 --------------
 arch/sparc/include/asm/tlbflush_64.h          |  2 +-
 arch/sparc/mm/tlb.c                           | 12 ++++---
 include/linux/pgtable.h                       | 32 +++++++++++++-----
 mm/kasan/shadow.c                             |  5 ---
 mm/memory.c                                   | 33 ++++++++++++-------
 mm/vmalloc.c                                  |  6 ++++
 9 files changed, 65 insertions(+), 65 deletions(-)

-- 
2.48.1