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Date:   Wed, 24 Jul 2019 09:05:53 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Ralph Campbell <rcampbell@nvidia.com>
Cc:     linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        nouveau@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
        =?iso-8859-1?B?Suly9G1l?= Glisse <jglisse@redhat.com>,
        Jason Gunthorpe <jgg@mellanox.com>,
        Christoph Hellwig <hch@lst.de>, Ben Skeggs <bskeggs@redhat.com>
Subject: Re: [PATCH] mm/hmm: replace hmm_update with mmu_notifier_range
Message-ID: <20190724070553.GA2523@lst.de>
References: <20190723210506.25127-1-rcampbell@nvidia.com>
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Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>

One comment on a related cleanup:

>  	list_for_each_entry(mirror, &hmm->mirrors, list) {
>  		int rc;
>  
> -		rc = mirror->ops->sync_cpu_device_pagetables(mirror, &update);
> +		rc = mirror->ops->sync_cpu_device_pagetables(mirror, nrange);
>  		if (rc) {
> -			if (WARN_ON(update.blockable || rc != -EAGAIN))
> +			if (WARN_ON(mmu_notifier_range_blockable(nrange) ||
> +			    rc != -EAGAIN))
>  				continue;
>  			ret = -EAGAIN;
>  			break;

This magic handling of error seems odd.  I think we should merge rc and
ret into one variable and just break out if any error happens instead
or claiming in the comments -EAGAIN is the only valid error and then
ignoring all others here.