[PATCH v3 19/35] mm: write-lock VMAs before removing them from VMA tree
From: Suren Baghdasaryan <surenb@google.com>
Date: 2023-02-16 05:20:03
Also in:
linux-mm, lkml
Subsystem:
memory management, memory mapping, the rest · Maintainers:
Andrew Morton, Liam R. Howlett, Lorenzo Stoakes, Linus Torvalds
Write-locking VMAs before isolating them ensures that page fault handlers don't operate on isolated VMAs. Signed-off-by: Suren Baghdasaryan <surenb@google.com> --- mm/mmap.c | 1 + mm/nommu.c | 5 +++++ 2 files changed, 6 insertions(+)
diff --git a/mm/mmap.c b/mm/mmap.c
index 0eaa3d1a6cd1..aaa359a147b2 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c@@ -2261,6 +2261,7 @@ int split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma, static inline int munmap_sidetree(struct vm_area_struct *vma, struct ma_state *mas_detach) { + vma_start_write(vma); mas_set_range(mas_detach, vma->vm_start, vma->vm_end - 1); if (mas_store_gfp(mas_detach, vma, GFP_KERNEL)) return -ENOMEM;
diff --git a/mm/nommu.c b/mm/nommu.c
index 57ba243c6a37..2ab162d773e2 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c@@ -588,6 +588,7 @@ static int delete_vma_from_mm(struct vm_area_struct *vma) current->pid); return -ENOMEM; } + vma_start_write(vma); cleanup_vma_from_mm(vma); /* remove from the MM's tree and list */
@@ -1519,6 +1520,10 @@ void exit_mmap(struct mm_struct *mm) */ mmap_write_lock(mm); for_each_vma(vmi, vma) { + /* + * No need to lock VMA because this is the only mm user and no + * page fault handled can race with it. + */ cleanup_vma_from_mm(vma); delete_vma(mm, vma); cond_resched();
--
2.39.1