The patch titled
Subject: mremap: take anon_vma lock in shared mode
has been added to the -mm tree. Its filename is
mremap-take-anon_vma-lock-in-shared-mode.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mremap-take-anon_vma-lock-in-shared-mode.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mremap-take-anon_vma-lock-in-shared-mode.patch
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From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Subject: mremap: take anon_vma lock in shared mode
There's no modification to anon_vma interval tree. We only need to
serialize against exclusive rmap walker who wants to catch all ptes the
page is mapped with. Shared lock is enough for that.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Suggested-by: Davidlohr Bueso <dbueso@xxxxxxx>
Acked-by: Rik van Riel <riel@xxxxxxxxxx>
Cc: Michel Lespinasse <walken@xxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mremap.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff -puN mm/mremap.c~mremap-take-anon_vma-lock-in-shared-mode mm/mremap.c
--- a/mm/mremap.c~mremap-take-anon_vma-lock-in-shared-mode
+++ a/mm/mremap.c
@@ -123,7 +123,7 @@ static void move_ptes(struct vm_area_str
}
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_str
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
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;
_
Patches currently in -mm which might be from kirill.shutemov@xxxxxxxxxxxxxxx are
mm-free-compound-page-with-correct-order.patch
mm-thp-fix-collapsing-of-hugepages-on-madvise.patch
mm-verify-compound-order-when-freeing-a-page.patch
thp-do-not-mark-zero-page-pmd-write-protected-explicitly.patch
mremap-take-anon_vma-lock-in-shared-mode.patch
mm-introduce-do_shared_fault-and-drop-do_fault-fix-fix.patch
do_shared_fault-check-that-mmap_sem-is-held.patch
mm-replace-remap_file_pages-syscall-with-emulation.patch
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