linux-kernel - Re: [PATCH v4 2/2] kvm: Use huge pages for DAX-backed files

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Date:   Thu, 12 Dec 2019 11:31:50 -0500
From:   Barret Rhoden <brho@...gle.com>
To:     David Hildenbrand <david@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Alexander Duyck <alexander.h.duyck@...ux.intel.com>
Cc:     linux-nvdimm@...ts.01.org, x86@...nel.org, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, jason.zeng@...el.com
Subject: Re: [PATCH v4 2/2] kvm: Use huge pages for DAX-backed files

On 12/12/19 7:22 AM, David Hildenbrand wrote:
>> +	/*
>> +	 * Our caller grabbed the KVM mmu_lock with a successful
>> +	 * mmu_notifier_retry, so we're safe to walk the page table.
>> +	 */
>> +	switch (dev_pagemap_mapping_shift(hva, current->mm)) {
>> +	case PMD_SHIFT:
>> +	case PUD_SIZE:
> 
> Shouldn't this be PUD_SHIFT?
> 
> But I agree with Paolo, that this is simply
> 
> return dev_pagemap_mapping_shift(hva, current->mm) > PAGE_SHIFT;

Yes, good call.  I'll fix that in the next version.