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Date: Fri, 19 Apr 2024 14:58:43 +0200
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Subject: Re: [PATCH v13 04/26] KVM: guest_memfd: Fix PTR_ERR() handling in
 __kvm_gmem_get_pfn()
To: Michael Roth <michael.roth@amd.com>, kvm@vger.kernel.org
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References: <20240418194133.1452059-1-michael.roth@amd.com>
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From: David Hildenbrand <david@redhat.com>
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In-Reply-To: <20240418194133.1452059-5-michael.roth@amd.com>
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On 18.04.24 21:41, Michael Roth wrote:
> kvm_gmem_get_folio() may return a PTR_ERR() rather than just NULL. In
> particular, for cases where EEXISTS is returned when FGP_CREAT_ONLY
> flag is used. Handle this properly in __kvm_gmem_get_pfn().
> 
> Signed-off-by: Michael Roth <michael.roth@amd.com>
> ---
>   virt/kvm/guest_memfd.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
> index ccf22e44f387..9d7c6a70c547 100644
> --- a/virt/kvm/guest_memfd.c
> +++ b/virt/kvm/guest_memfd.c
> @@ -580,8 +580,8 @@ static int __kvm_gmem_get_pfn(struct file *file, struct kvm_memory_slot *slot,
>   	}
>   
>   	folio = kvm_gmem_get_folio(file_inode(file), index, prepare);
> -	if (!folio)
> -		return -ENOMEM;
> +	if (IS_ERR_OR_NULL(folio))
> +		return folio ? PTR_ERR(folio) : -ENOMEM;

Will it even return NULL?  Staring at other filemap_grab_folio() users, 
they all check for IS_ERR().

>   
>   	if (folio_test_hwpoison(folio)) {
>   		r = -EHWPOISON;

Do we have a Fixes: tag?

-- 
Cheers,

David / dhildenb