From: Christoph Hellwig <hch@infradead.org>
To: Peter Xu <peterx@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
James Houghton <jthoughton@google.com>,
Lorenzo Stoakes <lstoakes@gmail.com>,
David Hildenbrand <david@redhat.com>,
John Hubbard <jhubbard@nvidia.com>,
Yang Shi <shy828301@gmail.com>, Rik van Riel <riel@surriel.com>,
Hugh Dickins <hughd@google.com>,
linux-kernel@vger.kernel.org,
Matthew Wilcox <willy@infradead.org>,
Christoph Hellwig <hch@infradead.org>,
linux-mm@kvack.org, Mike Rapoport <rppt@kernel.org>,
Jason Gunthorpe <jgg@nvidia.com>,
"Kirill A . Shutemov" <kirill@shutemov.name>,
Axel Rasmussen <axelrasmussen@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
linuxppc-dev@lists.ozlabs.org, Vlastimil Babka <vbabka@suse.cz>,
Mike Kravetz <mike.kravetz@oracle.com>
Subject: Re: [PATCH RFC 06/12] mm/gup: Drop folio_fast_pin_allowed() in hugepd processing
Date: Wed, 22 Nov 2023 00:00:24 -0800 [thread overview]
Message-ID: <ZV21GCbG48nTLDzn@infradead.org> (raw)
In-Reply-To: <ZVzT5_3Zn-Y-6xth@x1n>
On Tue, Nov 21, 2023 at 10:59:35AM -0500, Peter Xu wrote:
> > What prevents us from ever using hugepd with file mappings? I think
> > it would naturally fit in with how large folios for the pagecache work.
> >
> > So keeping this check and generalizing it seems like the better idea to
> > me.
>
> But then it means we're still keeping that dead code for fast-gup even if
> we know that fact.. Or do we have a plan to add that support very soon, so
> this code will be destined to add back?
The question wasn't mean retorical - we support arbitrary power of two
sized folios for the pagepage, what prevents us from using hugepd with
them right now?
> The other option is I can always add a comment above gup_huge_pd()
> explaining this special bit, so that when someone is adding hugepd support
> to file large folios we'll hopefully not forget it? But then that
> generalization work will only happen when the code will be needed.
If dropping the check is the right thing for now (and I think the ppc
maintainers and willy as the large folio guy might have a more useful
opinions than I do), leaving a comment in would be very useful.
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@infradead.org>
To: Peter Xu <peterx@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Andrea Arcangeli <aarcange@redhat.com>,
James Houghton <jthoughton@google.com>,
Lorenzo Stoakes <lstoakes@gmail.com>,
David Hildenbrand <david@redhat.com>,
Vlastimil Babka <vbabka@suse.cz>,
John Hubbard <jhubbard@nvidia.com>,
Yang Shi <shy828301@gmail.com>, Rik van Riel <riel@surriel.com>,
Hugh Dickins <hughd@google.com>,
Matthew Wilcox <willy@infradead.org>,
Jason Gunthorpe <jgg@nvidia.com>,
Axel Rasmussen <axelrasmussen@google.com>,
"Kirill A . Shutemov" <kirill@shutemov.name>,
Andrew Morton <akpm@linux-foundation.org>,
linuxppc-dev@lists.ozlabs.org, Mike Rapoport <rppt@kernel.org>,
Mike Kravetz <mike.kravetz@oracle.com>
Subject: Re: [PATCH RFC 06/12] mm/gup: Drop folio_fast_pin_allowed() in hugepd processing
Date: Wed, 22 Nov 2023 00:00:24 -0800 [thread overview]
Message-ID: <ZV21GCbG48nTLDzn@infradead.org> (raw)
In-Reply-To: <ZVzT5_3Zn-Y-6xth@x1n>
On Tue, Nov 21, 2023 at 10:59:35AM -0500, Peter Xu wrote:
> > What prevents us from ever using hugepd with file mappings? I think
> > it would naturally fit in with how large folios for the pagecache work.
> >
> > So keeping this check and generalizing it seems like the better idea to
> > me.
>
> But then it means we're still keeping that dead code for fast-gup even if
> we know that fact.. Or do we have a plan to add that support very soon, so
> this code will be destined to add back?
The question wasn't mean retorical - we support arbitrary power of two
sized folios for the pagepage, what prevents us from using hugepd with
them right now?
> The other option is I can always add a comment above gup_huge_pd()
> explaining this special bit, so that when someone is adding hugepd support
> to file large folios we'll hopefully not forget it? But then that
> generalization work will only happen when the code will be needed.
If dropping the check is the right thing for now (and I think the ppc
maintainers and willy as the large folio guy might have a more useful
opinions than I do), leaving a comment in would be very useful.
next prev parent reply other threads:[~2023-11-22 8:01 UTC|newest]
Thread overview: 89+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-16 1:28 [PATCH RFC 00/12] mm/gup: Unify hugetlb, part 2 Peter Xu
2023-11-16 1:28 ` [PATCH RFC 01/12] mm/hugetlb: Export hugetlbfs_pagecache_present() Peter Xu
2023-11-23 7:23 ` Christoph Hellwig
2023-11-23 16:05 ` Peter Xu
2023-11-16 1:28 ` [PATCH RFC 02/12] mm: Provide generic pmd_thp_or_huge() Peter Xu
2023-11-16 1:28 ` [PATCH RFC 03/12] mm: Export HPAGE_PXD_* macros even if !THP Peter Xu
2023-11-23 7:23 ` Christoph Hellwig
2023-11-23 9:53 ` Mike Rapoport
2023-11-23 15:27 ` Peter Xu
2023-11-16 1:29 ` [PATCH RFC 04/12] mm: Introduce vma_pgtable_walk_{begin|end}() Peter Xu
2023-11-23 7:24 ` Christoph Hellwig
2023-11-23 16:11 ` Peter Xu
2023-11-24 4:02 ` Aneesh Kumar K.V
2023-11-24 15:34 ` Peter Xu
2023-11-16 1:29 ` [PATCH RFC 05/12] mm/gup: Fix follow_devmap_p[mu]d() to return even if NULL Peter Xu
2023-11-23 7:25 ` Christoph Hellwig
2023-11-23 17:59 ` Peter Xu
2023-11-16 1:29 ` [PATCH RFC 06/12] mm/gup: Drop folio_fast_pin_allowed() in hugepd processing Peter Xu
2023-11-16 1:29 ` Peter Xu
2023-11-20 8:26 ` Christoph Hellwig
2023-11-20 8:26 ` Christoph Hellwig
2023-11-21 15:59 ` Peter Xu
2023-11-21 15:59 ` Peter Xu
2023-11-22 8:00 ` Christoph Hellwig [this message]
2023-11-22 8:00 ` Christoph Hellwig
2023-11-22 15:22 ` Peter Xu
2023-11-22 15:22 ` Peter Xu
2023-11-23 7:21 ` Christoph Hellwig
2023-11-23 7:21 ` Christoph Hellwig
2023-11-23 16:10 ` Peter Xu
2023-11-23 16:10 ` Peter Xu
2023-11-23 18:22 ` Christophe Leroy
2023-11-23 18:22 ` Christophe Leroy
2023-11-23 19:37 ` Peter Xu
2023-11-23 19:37 ` Peter Xu
2023-11-24 5:28 ` Aneesh Kumar K.V
2023-11-24 5:28 ` Aneesh Kumar K.V
2023-11-24 7:03 ` Christophe Leroy
2023-11-24 7:03 ` Christophe Leroy
2023-11-24 18:16 ` Peter Xu
2023-11-24 18:16 ` Peter Xu
2023-11-24 1:06 ` Michael Ellerman
2023-11-24 1:06 ` Michael Ellerman
2023-11-23 15:47 ` Matthew Wilcox
2023-11-23 15:47 ` Matthew Wilcox
2023-11-23 17:22 ` Peter Xu
2023-11-23 17:22 ` Peter Xu
2023-11-23 19:11 ` Ryan Roberts
2023-11-23 19:11 ` Ryan Roberts
2023-11-23 19:46 ` Peter Xu
2023-11-23 19:46 ` Peter Xu
2023-11-24 9:06 ` Ryan Roberts
2023-11-24 9:06 ` Ryan Roberts
2023-11-24 16:07 ` Peter Xu
2023-11-24 16:07 ` Peter Xu
2023-11-30 21:30 ` Peter Xu
2023-11-30 21:30 ` Peter Xu
2023-12-03 13:33 ` Christophe Leroy
2023-12-03 13:33 ` Christophe Leroy
2023-12-04 11:11 ` Ryan Roberts
2023-12-04 11:11 ` Ryan Roberts
2023-12-04 11:25 ` Christophe Leroy
2023-12-04 11:25 ` Christophe Leroy
2023-12-04 11:46 ` Ryan Roberts
2023-12-04 11:46 ` Ryan Roberts
2023-12-04 11:57 ` Christophe Leroy
2023-12-04 11:57 ` Christophe Leroy
2023-12-04 12:02 ` Ryan Roberts
2023-12-04 12:02 ` Ryan Roberts
2023-12-04 16:48 ` Peter Xu
2023-12-04 16:48 ` Peter Xu
2023-11-16 1:29 ` [PATCH RFC 07/12] mm/gup: Refactor record_subpages() to find 1st small page Peter Xu
2023-11-16 14:51 ` Matthew Wilcox
2023-11-16 19:40 ` Peter Xu
2023-11-16 19:41 ` Matthew Wilcox
2023-11-16 1:29 ` [PATCH RFC 08/12] mm/gup: Handle hugetlb for no_page_table() Peter Xu
2023-11-16 14:58 ` kernel test robot
2023-11-23 7:26 ` Christoph Hellwig
2023-11-16 1:29 ` [PATCH RFC 09/12] mm/gup: Handle huge pud for follow_pud_mask() Peter Xu
2023-11-16 15:30 ` kernel test robot
2023-11-23 7:28 ` Christoph Hellwig
2023-11-23 16:19 ` Peter Xu
2023-11-16 1:29 ` [PATCH RFC 10/12] mm/gup: Handle huge pmd for follow_pmd_mask() Peter Xu
2023-11-16 15:53 ` kernel test robot
2023-11-16 1:29 ` [PATCH RFC 11/12] mm/gup: Handle hugepd for follow_page() Peter Xu
2023-11-16 1:29 ` [PATCH RFC 12/12] mm/gup: Merge hugetlb into generic mm code Peter Xu
2023-11-23 7:29 ` Christoph Hellwig
2023-11-23 16:21 ` Peter Xu
2023-11-22 14:51 ` [PATCH RFC 00/12] mm/gup: Unify hugetlb, part 2 Jason Gunthorpe
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