[PATCH v2 20/33] mm/mmap: write-lock adjacent VMAs if they can grow into... | linuxppc-dev

[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

STALE1200d

[PATCH v2 20/33] mm/mmap: write-lock adjacent VMAs if they can grow into unmapped area

From: Suren Baghdasaryan <surenb@google.com>
Date: 2023-01-27 19:45:18
Also in: linux-arm-kernel, linux-mm, lkml
Subsystem: memory management, memory mapping, the rest · Maintainers: Andrew Morton, Liam R. Howlett, Lorenzo Stoakes, Linus Torvalds

While unmapping VMAs, adjacent VMAs might be able to grow into the area
being unmapped. In such cases write-lock adjacent VMAs to prevent this
growth.

Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
 mm/mmap.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 57cb3a2ac9b1..3baf218836bb 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c

@@ -2399,11 +2399,13 @@ do_vmi_align_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
 	 * down_read(mmap_lock) and collide with the VMA we are about to unmap.
 	 */
 	if (downgrade) {
-		if (next && (next->vm_flags & VM_GROWSDOWN))
+		if (next && (next->vm_flags & VM_GROWSDOWN)) {
+			vma_start_write(next);
 			downgrade = false;
-		else if (prev && (prev->vm_flags & VM_GROWSUP))
+		} else if (prev && (prev->vm_flags & VM_GROWSUP)) {
+			vma_start_write(prev);
 			downgrade = false;
-		else
+		} else
 			mmap_write_downgrade(mm);
 	}

-- 
2.39.1

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