There's no modification to anon_vma interval tree. We only need to
serialize against exclusive rmap walker who want s to catch all ptes the
page is mapped with. Shared lock is enough for that.
Suggested-by: Davidlohr Bueso <dbueso@xxxxxxx>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
mm/mremap.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/mm/mremap.c b/mm/mremap.c
index c855922497a3..1e35ba664406 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -123,7 +123,7 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
}
if (vma->anon_vma) {
anon_vma = vma->anon_vma;
- anon_vma_lock_write(anon_vma);
+ anon_vma_lock_read(anon_vma);
}
}
@@ -154,7 +154,7 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
pte_unmap(new_pte - 1);
pte_unmap_unlock(old_pte - 1, old_ptl);
if (anon_vma)
- anon_vma_unlock_write(anon_vma);
+ anon_vma_unlock_read(anon_vma);
if (mapping)
mutex_unlock(&mapping->i_mmap_mutex);
}
@@ -199,12 +199,12 @@ unsigned long move_page_tables(struct vm_area_struct *vma,
vma);
/* See comment in move_ptes() */
if (need_rmap_locks)
- anon_vma_lock_write(vma->anon_vma);
+ anon_vma_lock_read(vma->anon_vma);
err = move_huge_pmd(vma, new_vma, old_addr,
new_addr, old_end,
old_pmd, new_pmd);
if (need_rmap_locks)
- anon_vma_unlock_write(vma->anon_vma);
+ anon_vma_unlock_read(vma->anon_vma);
}
if (err > 0) {
need_flush = true;
--
2.1.1
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