From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jason Gunthorpe <jgg@ziepe.ca>
Date: Fri, 20 Mar 2020 12:58:13 +0000
Subject: Re: [PATCH 3/4] mm: simplify device private page handling in hmm_range_fault
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To: Ralph Campbell <rcampbell@nvidia.com>
Cc: Christoph Hellwig <hch@lst.de>, Dan Williams <dan.j.williams@intel.com>, Bharata B Rao <bharata@linux.ibm.com>, Christian =?utf-8?B?S8O2bmln?= <christian.koenig@amd.com>, Ben Skeggs <bskeggs@redhat.com>, Jerome Glisse <jglisse@redhat.com>, kvm-ppc@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org, linux-mm@kvack.org

On Thu, Mar 19, 2020 at 06:33:04PM -0700, Ralph Campbell wrote:

> > > +		.default_flags = dmirror_hmm_flags[HMM_PFN_VALID] |
> > > +				(write ? dmirror_hmm_flags[HMM_PFN_WRITE] : 0),
> > > +		.dev_private_owner = dmirror->mdevice,
> > > +	};
> > > +	int ret = 0;
> > 
> > > +static int dmirror_snapshot(struct dmirror *dmirror,
> > > +			    struct hmm_dmirror_cmd *cmd)
> > > +{
> > > +	struct mm_struct *mm = dmirror->mm;
> > > +	unsigned long start, end;
> > > +	unsigned long size = cmd->npages << PAGE_SHIFT;
> > > +	unsigned long addr;
> > > +	unsigned long next;
> > > +	uint64_t pfns[64];
> > > +	unsigned char perm[64];
> > > +	char __user *uptr;
> > > +	struct hmm_range range = {
> > > +		.pfns = pfns,
> > > +		.flags = dmirror_hmm_flags,
> > > +		.values = dmirror_hmm_values,
> > > +		.pfn_shift = DPT_SHIFT,
> > > +		.pfn_flags_mask = ~0ULL,
> > 
> > Same here, especially since this is snapshot
> > 
> > Jason
> 
> Actually, snapshot ignores pfn_flags_mask and default_flags.

Yes, so no reason to set them to not 0..

Jason