linux-kernel - Re: [PATCH] drm/amdkfd: use vma_lookup() instead of find

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Message-ID: <a1d36d76-396a-0bf0-26b7-c009fbae5dd0@amd.com>
Date:   Mon, 17 Oct 2022 15:35:25 -0400
From:   Felix Kuehling <felix.kuehling@....com>
To:     Deming Wang <wangdeming@...pur.com>, airlied@...il.com,
        daniel@...ll.ch, alexander.deucher@....com,
        christian.koenig@....com, Xinhui.Pan@....com
Cc:     amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/amdkfd: use vma_lookup() instead of find_vma()


On 2022-10-06 22:48, Deming Wang wrote:
> Using vma_lookup() verifies the start address is contained in the found
> vma.  This results in easier to read the code.

Thank you for the patches. This and your other patch look good to me. 
However, you missed one use of find_vma in svm_range_is_valid. Is that 
an oversight or is there a reason why we need to use find_vma there?

If you're going to respin it, you may also squash the two patches into one.

Thanks,
   Felix


>
> Signed-off-by: Deming Wang <wangdeming@...pur.com>
> ---
>   drivers/gpu/drm/amd/amdkfd/kfd_svm.c | 12 ++++++------
>   1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
> index 64fdf63093a0..cabcc2ca3c23 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
> @@ -1586,8 +1586,8 @@ static int svm_range_validate_and_map(struct mm_struct *mm,
>   		unsigned long npages;
>   		bool readonly;
>   
> -		vma = find_vma(mm, addr);
> -		if (!vma || addr < vma->vm_start) {
> +		vma = vma_lookup(mm, addr);
> +		if (!vma) {
>   			r = -EFAULT;
>   			goto unreserve_out;
>   		}
> @@ -2542,8 +2542,8 @@ svm_range_get_range_boundaries(struct kfd_process *p, int64_t addr,
>   	struct interval_tree_node *node;
>   	unsigned long start_limit, end_limit;
>   
> -	vma = find_vma(p->mm, addr << PAGE_SHIFT);
> -	if (!vma || (addr << PAGE_SHIFT) < vma->vm_start) {
> +	vma = vma_lookup(p->mm, addr << PAGE_SHIFT);
> +	if (!vma) {
>   		pr_debug("VMA does not exist in address [0x%llx]\n", addr);
>   		return -EFAULT;
>   	}
> @@ -2871,8 +2871,8 @@ svm_range_restore_pages(struct amdgpu_device *adev, unsigned int pasid,
>   	/* __do_munmap removed VMA, return success as we are handling stale
>   	 * retry fault.
>   	 */
> -	vma = find_vma(mm, addr << PAGE_SHIFT);
> -	if (!vma || (addr << PAGE_SHIFT) < vma->vm_start) {
> +	vma = vma_lookup(mm, addr << PAGE_SHIFT);
> +	if (!vma) {
>   		pr_debug("address 0x%llx VMA is removed\n", addr);
>   		r = 0;
>   		goto out_unlock_range;