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From:   Tiberiu Georgescu <tiberiu.georgescu@nutanix.com>
To:     Peter Xu <peterx@redhat.com>
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        Andrew Morton <akpm@linux-foundation.org>,
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        Matthew Wilcox <willy@infradead.org>,
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        Hugh Dickins <hughd@google.com>,
        Miaohe Lin <linmiaohe@huawei.com>,
        Mike Rapoport <rppt@linux.vnet.ibm.com>
Subject: Re: [PATCH v5 24/26] mm/pagemap: Recognize uffd-wp bit for
 shmem/hugetlbfs
Thread-Topic: [PATCH v5 24/26] mm/pagemap: Recognize uffd-wp bit for
 shmem/hugetlbfs
Thread-Index: AQHXebZmBTPHtO67e0+5F2gnOfKvWatKFHUA
Date:   Mon, 19 Jul 2021 09:53:36 +0000
Message-ID: <A83FCF8F-193E-4584-9442-C95B2635FD03@nutanix.com>
References: <20210715201422.211004-1-peterx@redhat.com>
 <20210715201651.212134-1-peterx@redhat.com>
In-Reply-To: <20210715201651.212134-1-peterx@redhat.com>
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Hello Peter,

> On 15 Jul 2021, at 21:16, Peter Xu <peterx@redhat.com> wrote:
>=20
> This requires the pagemap code to be able to recognize the newly introduc=
ed
> swap special pte for uffd-wp, meanwhile the general case for hugetlb that=
 we
> recently start to support.  It should make pagemap uffd-wp support comple=
te.
>=20
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
> fs/proc/task_mmu.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>=20
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index 9c5af77b5290..988e29fa1f00 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -1389,6 +1389,8 @@ static pagemap_entry_t pte_to_pagemap_entry(struct =
pagemapread *pm,
> 		flags |=3D PM_SWAP;
> 		if (is_pfn_swap_entry(entry))
> 			page =3D pfn_swap_entry_to_page(entry);
> +	} else if (pte_swp_uffd_wp_special(pte)) {
> +		flags |=3D PM_UFFD_WP;
> 	}

^ Would it not be important to also add PM_SWAP to flags?

Kind regards,
Tibi