4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Maor Gottlieb <maorg@xxxxxxxxxxxx>
[ 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@xxxxxxxxxxxx>
Signed-off-by: Leon Romanovsky <leon@xxxxxxxxxx>
Signed-off-by: Doug Ledford <dledford@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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);
}