4.4-stable review patch. If anyone has any objections, please let me know.
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From: Maor Gottlieb maorg@mellanox.com
[ Upstream commit 22c3653d04bd0c67b75e99d85e0c0bdf83947df5 ]
When the driver disassociate user context, it changes the vma to anonymous by setting the vm_ops to null and zap the vma ptes.
In order to avoid race in the kernel, we need to take write lock before we change the vma entries.
Fixes: ae184ddeca5db ('IB/mlx4_ib: Disassociate support') Signed-off-by: Maor Gottlieb maorg@mellanox.com Signed-off-by: Leon Romanovsky leon@kernel.org Signed-off-by: Doug Ledford dledford@redhat.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/infiniband/hw/mlx4/main.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/infiniband/hw/mlx4/main.c +++ b/drivers/infiniband/hw/mlx4/main.c @@ -1041,7 +1041,7 @@ static void mlx4_ib_disassociate_ucontex /* need to protect from a race on closing the vma as part of * mlx4_ib_vma_close(). */ - down_read(&owning_mm->mmap_sem); + down_write(&owning_mm->mmap_sem); for (i = 0; i < HW_BAR_COUNT; i++) { vma = context->hw_bar_info[i].vma; if (!vma) @@ -1059,7 +1059,7 @@ static void mlx4_ib_disassociate_ucontex context->hw_bar_info[i].vma->vm_ops = NULL; }
- up_read(&owning_mm->mmap_sem); + up_write(&owning_mm->mmap_sem); mmput(owning_mm); put_task_struct(owning_process); }