Patch "IB/mlx5: Take write semaphore when changing the vma struct" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

IB/mlx5: Take write semaphore when changing the vma struct

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
ib-mlx5-take-write-semaphore-when-changing-the-vma-struct.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Maor Gottlieb <[email protected]>
Date: Wed, 29 Mar 2017 06:03:02 +0300
Subject: IB/mlx5: Take write semaphore when changing the vma struct

From: Maor Gottlieb <[email protected]>

[ Upstream commit ecc7d83be3243835c9396a1a2fb8ce95f205207b ]

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.

---
 drivers/infiniband/hw/mlx5/main.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

@@ -1313,7 +1313,7 @@ static void mlx5_ib_disassociate_ucontex
 	/* need to protect from a race on closing the vma as part of
 	 * mlx5_ib_vma_close.
 	 */
-	down_read(&owning_mm->mmap_sem);
+	down_write(&owning_mm->mmap_sem);
 	list_for_each_entry_safe(vma_private, n, &context->vma_private_list,
 				 list) {
 		vma = vma_private->vma;

@@ -1327,7 +1327,7 @@ static void mlx5_ib_disassociate_ucontex
 		list_del(&vma_private->list);
 		kfree(vma_private);
 	}
-	up_read(&owning_mm->mmap_sem);
+	up_write(&owning_mm->mmap_sem);
 	mmput(owning_mm);
 	put_task_struct(owning_process);
 }

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/ib-mlx4-change-vma-from-shared-to-private.patch queue-4.9/ib-mlx5-take-write-semaphore-when-changing-the-vma-struct.patch queue-4.9/ib-mlx5-change-vma-from-shared-to-private.patch queue-4.9/ib-mlx4-take-write-semaphore-when-changing-the-vma-struct.patch