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

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: 7c2344c3bb ('IB/mlx5: Implements disassociate_ucontext API')
Signed-off-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>
This commit is contained in:
Maor Gottlieb 2017-03-29 06:03:02 +03:00 committed by Doug Ledford
parent ca37a664a8
commit ecc7d83be3
1 changed files with 2 additions and 2 deletions
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4
drivers/infiniband/hw/mlx5/main.c
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@ -1478,7 +1478,7 @@ static void mlx5_ib_disassociate_ucontext(struct ib_ucontext *ibcontext)
/* 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;
@ -1492,7 +1492,7 @@ static void mlx5_ib_disassociate_ucontext(struct ib_ucontext *ibcontext)
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);
}