linux-kernel - [PATCH 0/6] tlb: Fix access and (soft-)dirty bit management

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Date:   Fri, 20 Nov 2020 14:35:51 +0000
From:   Will Deacon <will@...nel.org>
To:     linux-kernel@...r.kernel.org
Cc:     kernel-team@...roid.com, Will Deacon <will@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Yu Zhao <yuzhao@...gle.com>, Minchan Kim <minchan@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Anshuman Khandual <anshuman.khandual@....com>,
        linux-mm@...ck.org, linux-arm-kernel@...ts.infradead.org
Subject: [PATCH 0/6] tlb: Fix access and (soft-)dirty bit management

Hi all,

This series attempts to fix some issues relating to our access and
(soft-)dirty bit management relating to TLB invalidation. It's a bit all
over the place because I kept running into new issues as I was trying to
figure it out.

The first patch fixes a crash we've seen in practice. The other patches
are all addressing things that I found by code inspection and I would
_really_ appreciate others having a look. In particular, what can go
wrong in practice if a CPU has a stale, writable entry in the TLB for a
pte which is !pte_write()? It feels intuitively bad, but I couldn't find
anywhere that would explode (the CoW path looks alright, for example).

Cheers,

Will

Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Yu Zhao <yuzhao@...gle.com>
Cc: Minchan Kim <minchan@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Andrew Morton <akpm@...ux-foundation.org
Cc: Anshuman Khandual <anshuman.khandual@....com>
Cc: linux-mm@...ck.org
Cc: linux-arm-kernel@...ts.infradead.org

--->8

Will Deacon (6):
  arm64: pgtable: Fix pte_accessible()
  arm64: pgtable: Ensure dirty bit is preserved across pte_wrprotect()
  tlb: mmu_gather: Remove unused start/end arguments from
    tlb_finish_mmu()
  mm: proc: Invalidate TLB after clearing soft-dirty page state
  tlb: mmu_gather: Introduce tlb_gather_mmu_fullmm()
  mm: proc: Avoid fullmm flush for young/dirty bit toggling

 arch/arm64/include/asm/pgtable.h | 31 +++++++++++++++----------------
 arch/ia64/include/asm/tlb.h      |  2 +-
 arch/x86/kernel/ldt.c            |  2 +-
 fs/exec.c                        |  2 +-
 fs/proc/task_mmu.c               | 22 +++++++++++++---------
 include/asm-generic/tlb.h        |  6 ++++--
 include/linux/mm_types.h         |  4 ++--
 mm/hugetlb.c                     |  2 +-
 mm/madvise.c                     |  6 +++---
 mm/memory.c                      |  4 ++--
 mm/mmap.c                        |  6 +++---
 mm/mmu_gather.c                  | 21 +++++++++++++++------
 mm/oom_kill.c                    |  4 ++--
 13 files changed, 63 insertions(+), 49 deletions(-)

-- 
2.29.2.454.gaff20da3a2-goog