mm: replace vma_lock_anon_vma with anon_vma_lock_read/write
authorKonstantin Khlebnikov <koct9i@gmail.com>
Fri, 5 Feb 2016 23:36:50 +0000 (15:36 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Sat, 6 Feb 2016 02:10:40 +0000 (18:10 -0800)
commit12352d3cae2cebe18805a91fab34b534d7444231
tree07c3e85b4ca5fd3698855c66084fb939727f4f09
parentc95a51807b730e4681e2ecbdfd669ca52601959e
mm: replace vma_lock_anon_vma with anon_vma_lock_read/write

Sequence vma_lock_anon_vma() - vma_unlock_anon_vma() isn't safe if
anon_vma appeared between lock and unlock.  We have to check anon_vma
first or call anon_vma_prepare() to be sure that it's here.  There are
only few users of these legacy helpers.  Let's get rid of them.

This patch fixes anon_vma lock imbalance in validate_mm().  Write lock
isn't required here, read lock is enough.

And reorders expand_downwards/expand_upwards: security_mmap_addr() and
wrapping-around check don't have to be under anon vma lock.

Link: https://lkml.kernel.org/r/CACT4Y+Y908EjM2z=706dv4rV6dWtxTLK9nFg9_7DhRMLppBo2g@mail.gmail.com
Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
include/linux/rmap.h
mm/mmap.c