linux-kernel - [PATCH v2 00/15] move pagetable_*_dtor() to __tlb_remove

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Message-Id: <cover.1734526570.git.zhengqi.arch@bytedance.com>
Date: Wed, 18 Dec 2024 21:04:36 +0800
From: Qi Zheng <zhengqi.arch@...edance.com>
To: peterz@...radead.org,
	tglx@...utronix.de,
	david@...hat.com,
	jannh@...gle.com,
	hughd@...gle.com,
	yuzhao@...gle.com,
	willy@...radead.org,
	muchun.song@...ux.dev,
	vbabka@...nel.org,
	lorenzo.stoakes@...cle.com,
	akpm@...ux-foundation.org,
	rientjes@...gle.com,
	vishal.moola@...il.com
Cc: linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Qi Zheng <zhengqi.arch@...edance.com>
Subject: [PATCH v2 00/15] move pagetable_*_dtor() to __tlb_remove_table()

Changes in v2:
 - add [PATCH v2 13|14|15/15] (suggested by Peter Zijlstra)
 - add Originally-bys and Suggested-bys
 - rebase onto the next-20241218

Hi all,

As proposed [1] by Peter Zijlstra below, this patch series aims to move
pagetable_*_dtor() into __tlb_remove_table(). This will cleanup pagetable_*_dtor()
a bit and more gracefully fix the UAF issue [2] reported by syzbot.

```
Notably:

 - s390 pud isn't calling the existing pagetable_pud_[cd]tor()
 - none of the p4d things have pagetable_p4d_[cd]tor() (x86,arm64,s390,riscv)
   and they have inconsistent accounting
 - while much of the _ctor calls are in generic code, many of the _dtor
   calls are in arch code for hysterial raisins, this could easily be
   fixed
 - if we fix ptlock_free() to handle NULL, then all the _dtor()
   functions can use it, and we can observe they're all identical
   and can be folded

after all that cleanup, you can move the _dtor from *_free_tlb() into
tlb_remove_table() -- which for the above case, would then have it
called from __tlb_remove_table_free().
```

And hi Andrew, I developed the code based on the latest linux-next, so I reverted
the "mm: pgtable: make ptlock be freed by RCU" first. Once the review of this
patch series is completed, the "mm: pgtable: make ptlock be freed by RCU" can be
dropped directly from mm tree, and this revert patch will not be needed.

This series is based on next-20241218. And I tested this patch series on x86 and
only cross-compiled it on arm[|64], powerpc, riscv, s390 and sparc.

Comments and suggestions are welcome!

Thanks,
Qi

[1]. https://lore.kernel.org/all/20241211133433.GC12500@noisy.programming.kicks-ass.net/
[2]. https://lore.kernel.org/all/67548279.050a0220.a30f1.015b.GAE@google.com/

Qi Zheng (15):
  Revert "mm: pgtable: make ptlock be freed by RCU"
  mm: pgtable: introduce generic p4d_alloc_one() and p4d_free()
  arm64: pgtable: use mmu gather to free p4d level page table
  s390: pgtable: add statistics for PUD and P4D level page table
  mm: pgtable: introduce pagetable_dtor()
  arm: pgtable: move pagetable_dtor() to __tlb_remove_table()
  arm64: pgtable: move pagetable_dtor() to __tlb_remove_table()
  riscv: pgtable: move pagetable_dtor() to __tlb_remove_table()
  x86: pgtable: move pagetable_dtor() to __tlb_remove_table()
  s390: pgtable: also move pagetable_dtor() of PxD to
    __tlb_remove_table()
  mm: pgtable: introduce generic __tlb_remove_table()
  mm: pgtable: move __tlb_remove_table_one() in x86 to generic file
  mm: pgtable: remove tlb_remove_page_ptdesc()
  mm: pgtable: remove tlb_remove_ptdesc()
  mm: pgtable: introduce generic pagetable_dtor_free()

 Documentation/mm/split_page_table_lock.rst |  4 +-
 arch/arm/include/asm/tlb.h                 | 18 +-----
 arch/arm64/include/asm/pgalloc.h           | 17 +++---
 arch/arm64/include/asm/tlb.h               | 31 +++++-----
 arch/csky/include/asm/pgalloc.h            |  4 +-
 arch/hexagon/include/asm/pgalloc.h         |  4 +-
 arch/loongarch/include/asm/pgalloc.h       |  4 +-
 arch/m68k/include/asm/mcf_pgalloc.h        |  4 +-
 arch/m68k/include/asm/sun3_pgalloc.h       |  4 +-
 arch/m68k/mm/motorola.c                    |  2 +-
 arch/mips/include/asm/pgalloc.h            |  4 +-
 arch/nios2/include/asm/pgalloc.h           |  4 +-
 arch/openrisc/include/asm/pgalloc.h        |  4 +-
 arch/powerpc/include/asm/tlb.h             |  1 +
 arch/powerpc/mm/book3s64/mmu_context.c     |  2 +-
 arch/powerpc/mm/book3s64/pgtable.c         |  2 +-
 arch/powerpc/mm/pgtable-frag.c             |  4 +-
 arch/riscv/include/asm/pgalloc.h           | 57 ++++++++----------
 arch/riscv/include/asm/tlb.h               | 18 ------
 arch/riscv/mm/init.c                       |  4 +-
 arch/s390/include/asm/pgalloc.h            | 31 +++++++---
 arch/s390/include/asm/tlb.h                | 43 +++++++-------
 arch/s390/mm/pgalloc.c                     | 31 ++--------
 arch/sh/include/asm/pgalloc.h              |  4 +-
 arch/sparc/include/asm/tlb_32.h            |  1 +
 arch/sparc/include/asm/tlb_64.h            |  1 +
 arch/sparc/mm/init_64.c                    |  2 +-
 arch/sparc/mm/srmmu.c                      |  2 +-
 arch/um/include/asm/pgalloc.h              | 12 ++--
 arch/x86/include/asm/pgalloc.h             | 16 +++--
 arch/x86/include/asm/tlb.h                 | 33 -----------
 arch/x86/kernel/paravirt.c                 |  1 +
 arch/x86/mm/pgtable.c                      | 13 ++---
 include/asm-generic/pgalloc.h              | 68 +++++++++++++++++-----
 include/asm-generic/tlb.h                  | 23 ++++----
 include/linux/mm.h                         | 52 +++++++----------
 include/linux/mm_types.h                   |  9 +--
 mm/memory.c                                | 23 +++-----
 mm/mmu_gather.c                            | 19 +++++-
 39 files changed, 255 insertions(+), 321 deletions(-)

-- 
2.20.1