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IB/mlx4: 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: ae184ddeca ('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>
This commit is contained in:
Maor Gottlieb 2017-03-29 06:03:00 +03:00 committed by Doug Ledford
parent fb7a91746a
commit 22c3653d04
1 changed files with 2 additions and 2 deletions
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4
drivers/infiniband/hw/mlx4/main.c
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@ -1173,7 +1173,7 @@ static void mlx4_ib_disassociate_ucontext(struct ib_ucontext *ibcontext)
/* 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)
@ -1191,7 +1191,7 @@ static void mlx4_ib_disassociate_ucontext(struct ib_ucontext *ibcontext)
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);
}