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Commit 0021b461 authored by Maor Gottlieb's avatar Maor Gottlieb Committed by Greg Kroah-Hartman
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IB/mlx4: Take write semaphore when changing the vma struct 




[ 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: ae184dde ('IB/mlx4_ib: Disassociate support')
Signed-off-by: default avatarMaor Gottlieb <maorg@mellanox.com>
Signed-off-by: default avatarLeon Romanovsky <leon@kernel.org>
Signed-off-by: default avatarDoug Ledford <dledford@redhat.com>
Signed-off-by: default avatarSasha Levin <alexander.levin@microsoft.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 2b09da0e

drivers/infiniband/hw/mlx4/main.c

+2 −2
Original line number Diff line number Diff line
@@ -1168,7 +1168,7 @@ 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)
@@ -1186,7 +1186,7 @@ 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);

}