linux-kernel - Re: [RFC PATCH v2 33/51] KVM: guest_memfd: Allocate and truncate from custom allocator

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Message-ID: <d0b582cc-0cf7-4cdc-b148-d8f61dea7253@linux.intel.com>
Date: Tue, 3 Jun 2025 15:43:56 +0800
From: Binbin Wu <binbin.wu@...ux.intel.com>
To: Ackerley Tng <ackerleytng@...gle.com>
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Subject: Re: [RFC PATCH v2 33/51] KVM: guest_memfd: Allocate and truncate from
 custom allocator



On 5/15/2025 7:42 AM, Ackerley Tng wrote:
[...]
>   
>   	list_for_each_entry(gmem, gmem_list, entry)
>   		kvm_gmem_invalidate_end(gmem, start, end);
> @@ -776,6 +879,16 @@ static long kvm_gmem_allocate(struct inode *inode, loff_t offset, loff_t len)
>   
>   	start = offset >> PAGE_SHIFT;
>   	end = (offset + len) >> PAGE_SHIFT;
> +	if (kvm_gmem_has_custom_allocator(inode)) {
> +		size_t nr_pages;
> +		void *p;
> +
> +		p = kvm_gmem_allocator_private(inode);
> +		nr_pages = kvm_gmem_allocator_ops(inode)->nr_pages_in_folio(p);
> +
> +		start = round_down(start, nr_pages);
> +		end = round_down(end, nr_pages);
It's weird here.
Should the end be round_up()?

> +	}
>   
>   	r = 0;
>   	for (index = start; index < end; ) {
>
[...]