From: David Hildenbrand <david@redhat.com>
To: Peter Xu <peterx@redhat.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: Andrea Arcangeli <aarcange@redhat.com>,
Mike Rapoport <rppt@kernel.org>,
Matthew Wilcox <willy@infradead.org>,
Vlastimil Babka <vbabka@suse.cz>,
John Hubbard <jhubbard@nvidia.com>,
"Kirill A . Shutemov" <kirill@shutemov.name>,
James Houghton <jthoughton@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Lorenzo Stoakes <lstoakes@gmail.com>,
Hugh Dickins <hughd@google.com>,
Mike Kravetz <mike.kravetz@oracle.com>,
Jason Gunthorpe <jgg@nvidia.com>
Subject: Re: [PATCH v2 2/8] mm/hugetlb: Prepare hugetlb_follow_page_mask() for FOLL_PIN
Date: Tue, 20 Jun 2023 17:28:28 +0200 [thread overview]
Message-ID: <7cd1db3f-9bdf-dc0b-692c-380a2fa14286@redhat.com> (raw)
In-Reply-To: <20230619231044.112894-3-peterx@redhat.com>
On 20.06.23 01:10, Peter Xu wrote:
> follow_page() doesn't use FOLL_PIN, meanwhile hugetlb seems to not be the
> target of FOLL_WRITE either. However add the checks.
>
> Namely, either the need to CoW due to missing write bit, or proper CoR on
> !AnonExclusive pages over R/O pins to reject the follow page. That brings
> this function closer to follow_hugetlb_page().
>
> So we don't care before, and also for now. But we'll care if we switch
> over slow-gup to use hugetlb_follow_page_mask(). We'll also care when to
> return -EMLINK properly, as that's the gup internal api to mean "we should
> do CoR". Not really needed for follow page path, though.
>
> When at it, switching the try_grab_page() to use WARN_ON_ONCE(), to be
> clear that it just should never fail.
Oh, and does this comment really belong into this patch or am I confused?
--
Cheers,
David / dhildenb
next prev parent reply other threads:[~2023-06-20 15:28 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-19 23:10 [PATCH v2 0/8] mm/gup: Unify hugetlb, speed up thp Peter Xu
2023-06-19 23:10 ` [PATCH v2 1/8] mm/hugetlb: Handle FOLL_DUMP well in follow_page_mask() Peter Xu
2023-06-19 23:10 ` [PATCH v2 2/8] mm/hugetlb: Prepare hugetlb_follow_page_mask() for FOLL_PIN Peter Xu
2023-06-20 15:22 ` David Hildenbrand
2023-06-20 16:03 ` Peter Xu
2023-06-20 15:28 ` David Hildenbrand [this message]
2023-06-20 16:06 ` Peter Xu
2023-06-19 23:10 ` [PATCH v2 3/8] mm/hugetlb: Add page_mask for hugetlb_follow_page_mask() Peter Xu
2023-06-20 15:23 ` David Hildenbrand
2023-06-20 16:28 ` Peter Xu
2023-06-20 17:54 ` David Hildenbrand
2023-06-19 23:10 ` [PATCH v2 4/8] mm/gup: Cleanup next_page handling Peter Xu
2023-06-20 15:23 ` David Hildenbrand
2023-06-19 23:10 ` [PATCH v2 5/8] mm/gup: Accelerate thp gup even for "pages != NULL" Peter Xu
2023-06-20 15:43 ` David Hildenbrand
2023-06-20 16:23 ` Peter Xu
2023-06-20 18:02 ` David Hildenbrand
2023-06-20 20:12 ` Peter Xu
2023-06-20 21:43 ` Lorenzo Stoakes
2023-06-19 23:10 ` [PATCH v2 6/8] mm/gup: Retire follow_hugetlb_page() Peter Xu
2023-06-19 23:10 ` [PATCH v2 7/8] selftests/mm: Add -a to run_vmtests.sh Peter Xu
2023-06-19 23:10 ` [PATCH v2 8/8] selftests/mm: Add gup test matrix in run_vmtests.sh Peter Xu
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