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Date:   Mon, 25 Jul 2022 11:49:53 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Ralph Campbell <rcampbell@nvidia.com>
Cc:     <linux-mm@kvack.org>, Felix Kuehling <felix.kuehling@amd.com>,
        Philip Yang <Philip.Yang@amd.com>,
        Alistair Popple <apopple@nvidia.com>,
        Jason Gunthorpe <jgg@nvidia.com>, <stable@vger.kernel.org>
Subject: Re: [PATCH] mm/hmm: fault non-owner device private entries
Message-Id: <20220725114953.7e53ca4b296e0e753ca7bfda@linux-foundation.org>
In-Reply-To: <20220722225632.4101276-1-rcampbell@nvidia.com>
References: <20220722225632.4101276-1-rcampbell@nvidia.com>
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On Fri, 22 Jul 2022 15:56:32 -0700 Ralph Campbell <rcampbell@nvidia.com> wrote:

> If hmm_range_fault() is called with the HMM_PFN_REQ_FAULT flag and a
> device private PTE is found, the hmm_range::dev_private_owner page is
> used to determine if the device private page should not be faulted in.
> However, if the device private page is not owned by the caller,
> hmm_range_fault() returns an error instead of calling migrate_to_ram()
> to fault in the page.

Could we please include here a description of the end-user visible
effects of the bug?

> Cc: stable@vger.kernel.org

Especially when proposing a -stable backport.