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.
next prev parent reply other threads:[~2023-11-22 8:01 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20231116012908.392077-1-peterx@redhat.com>
2023-11-16 1:29 ` [PATCH RFC 06/12] mm/gup: Drop folio_fast_pin_allowed() in hugepd processing Peter Xu
2023-11-20 8:26 ` Christoph Hellwig
2023-11-21 15:59 ` Peter Xu
2023-11-22 8:00 ` Christoph Hellwig [this message]
2023-11-22 15:22 ` Peter Xu
2023-11-23 7:21 ` Christoph Hellwig
2023-11-23 16:10 ` Peter Xu
2023-11-23 18:22 ` Christophe Leroy
2023-11-23 19:37 ` Peter Xu
2023-11-24 5:28 ` Aneesh Kumar K.V
2023-11-24 7:03 ` Christophe Leroy
2023-11-24 18:16 ` Peter Xu
2023-11-24 1:06 ` Michael Ellerman
2023-11-23 15:47 ` Matthew Wilcox
2023-11-23 17:22 ` Peter Xu
2023-11-23 19:11 ` Ryan Roberts
2023-11-23 19:46 ` Peter Xu
2023-11-24 9:06 ` Ryan Roberts
2023-11-24 16:07 ` Peter Xu
2023-11-30 21:30 ` Peter Xu
2023-12-03 13:33 ` Christophe Leroy
2023-12-04 11:11 ` Ryan Roberts
2023-12-04 11:25 ` Christophe Leroy
2023-12-04 11:46 ` Ryan Roberts
2023-12-04 11:57 ` Christophe Leroy
2023-12-04 12:02 ` Ryan Roberts
2023-12-04 16:48 ` Peter Xu
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