Re: [PATCH v2 00/33] Per-VMA locks

[PATCH v2 00/33] Per-VMA locks · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 02/33] maple_tree: Detect dead nodes in mas_start() · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 05/33] maple_tree: Fix write memory barrier of nodes once dead for RCU mode · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 04/33] maple_tree: remove extra smp_wmb() from mas_dead_leaves() · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 06/33] maple_tree: Add smp_rmb() to dead node detection · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 07/33] mm: Enable maple tree RCU mode by default. · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 09/33] mm: rcu safe VMA freeing · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 10/33] mm: move mmap_lock assert function definitions · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 11/33] mm: add per-VMA lock and helper functions to control it · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 12/33] mm: mark VMA as being written when changing vm_flags · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 13/33] mm/mmap: move VMA locking before vma_adjust_trans_huge call · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 14/33] mm/khugepaged: write-lock VMA while collapsing a huge page · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 08/33] mm: introduce CONFIG_PER_VMA_LOCK · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 15/33] mm/mmap: write-lock VMAs before merging, splitting or expanding them · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 19/33] mm: conditionally write-lock VMA in free_pgtables · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 17/33] mm/mremap: write-lock VMA while remapping it to a new address range · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 22/33] mm/mmap: prevent pagefault handler from racing with mmu_notifier registration · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 20/33] mm/mmap: write-lock adjacent VMAs if they can grow into unmapped area · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 21/33] kernel/fork: assert no VMA readers during its destruction · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 23/33] mm: introduce lock_vma_under_rcu to be used from arch-specific code · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 27/33] mm: prevent userfaults to be handled under per-vma lock · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 28/33] mm: introduce per-VMA lock statistics · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 25/33] mm: add FAULT_FLAG_VMA_LOCK flag · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 29/33] x86/mm: try VMA lock-based page fault handling first · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 24/33] mm: fall back to mmap_lock if vma->anon_vma is not yet set · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 16/33] mm/mmap: write-lock VMA before shrinking or expanding it · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 31/33] powerc/mm: try VMA lock-based page fault handling first · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 32/33] mm/mmap: free vm_area_struct without call_rcu in exit_mmap · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 26/33] mm: prevent do_swap_page from handling page faults under VMA lock · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 30/33] arm64/mm: try VMA lock-based page fault handling first · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 33/33] mm: separate vma->lock from vm_area_struct · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 03/33] maple_tree: Fix freeing of nodes in rcu mode · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 18/33] mm: write-lock VMAs before removing them from VMA tree · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
[PATCH v2 01/33] maple_tree: Be more cautious about dead nodes · Suren Baghdasaryan <surenb@google.com> · 2023-01-27
Re: [PATCH v2 00/33] Per-VMA locks · Andrew Morton <akpm@linux-foundation.org> · 2023-01-27
Re: [PATCH v2 00/33] Per-VMA locks · Matthew Wilcox <willy@infradead.org> · 2023-01-27
Re: [PATCH v2 00/33] Per-VMA locks · Suren Baghdasaryan <surenb@google.com> · 2023-01-28
Re: [PATCH v2 00/33] Per-VMA locks · Suren Baghdasaryan <surenb@google.com> · 2023-02-14

From: Andrew Morton <akpm@linux-foundation.org>
Date: 2023-01-27 22:51:46
Also in: linux-arm-kernel, linux-mm, lkml

On Fri, 27 Jan 2023 11:40:37 -0800 Suren Baghdasaryan [off-list ref] wrote:

Per-vma locks idea that was discussed during SPF [1] discussion at LSF/MM
last year [2], which concluded with suggestion that “a reader/writer
semaphore could be put into the VMA itself; that would have the effect of
using the VMA as a sort of range lock. There would still be contention at
the VMA level, but it would be an improvement.” This patchset implements
this suggested approach.

I think I'll await reviewer/tester input for a while.

The patchset implements per-VMA locking only for anonymous pages which
are not in swap and avoids userfaultfs as their implementation is more
complex. Additional support for file-back page faults, swapped and user
pages can be added incrementally.

This is a significant risk.  How can we be confident that these as yet
unimplemented parts are implementable and that the result will be good?

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