From: Rik van Riel <riel@surriel.com>
To: John Hubbard <jhubbard@nvidia.com>,
"David Hildenbrand (Arm)" <david@kernel.org>,
linux-kernel@vger.kernel.org
Cc: kernel-team@meta.com, Andrew Morton <akpm@linux-foundation.org>,
Jason Gunthorpe <jgg@ziepe.ca>, Peter Xu <peterx@redhat.com>,
linux-mm@kvack.org
Subject: Re: [RFC PATCH v3 3/8] mm/gup: split follow_page_pte_commit() out of follow_page_pte()
Date: Sat, 22 Aug 2026 09:20:07 -0400 [thread overview]
Message-ID: <f86ca125a9b63cdab8edeb3c3b02a29141f18c1a.camel@surriel.com> (raw)
In-Reply-To: <fe9f0bb5-73e3-4509-951d-e529e37011fd@nvidia.com>
On Fri, 2026-08-21 at 15:04 -0700, John Hubbard wrote:
>
> You have delved too deep, and now uncovered something that's been
> a problem for the whole time. :)
>
> Specifically, "no, GUP should not be setting folios nor pages
> dirty", because that generally needs to be done as part of a
> filesystem
> coordinated set of steps. If the page is dirty, and the filesystem
> didn't expect it to be, that leads to problems.
>
> This is part of the big, remaining set of required fixes, that
> launched the creation of pin_user_pages*() and related. Connecting
> up the filesystems properly is yet to be done. And until then, this
> is a real defect.
>
Not just filesystems.
I found about two dozen places where drivers
fail to mark a page dirty after writing to
it, after obtaining the page from GUP.
I'll get out patches for that, unless there's
some reason I shouldn't.
--
All Rights Reversed.
next prev parent reply other threads:[~2026-08-22 13:20 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-11 2:51 [RFC PATCH v3 0/8] batch lookups in follow_page_mask() Rik van Riel
2026-08-11 2:51 ` [RFC PATCH v3 1/8] mm/gup: break out gup_fill_pages() helper Rik van Riel
2026-08-11 2:51 ` [RFC PATCH v3 2/8] mm/gup: convert follow_page_mask() to return a long Rik van Riel
2026-08-11 2:51 ` [RFC PATCH v3 3/8] mm/gup: split follow_page_pte_commit() out of follow_page_pte() Rik van Riel
2026-08-12 11:50 ` David Hildenbrand (Arm)
2026-08-12 13:02 ` Rik van Riel
2026-08-12 13:23 ` David Hildenbrand (Arm)
2026-08-12 16:19 ` Rik van Riel
2026-08-21 17:38 ` Rik van Riel
2026-08-21 22:04 ` John Hubbard
2026-08-22 13:20 ` Rik van Riel [this message]
2026-08-22 21:31 ` John Hubbard
2026-08-24 13:20 ` Rik van Riel
2026-08-11 2:51 ` [RFC PATCH v3 4/8] mm/gup: break out follow_one_pte() helper Rik van Riel
2026-08-11 2:51 ` [RFC PATCH v3 5/8] mm/gup: fill the pages array outside the pud/pmd lock Rik van Riel
2026-08-11 2:51 ` [RFC PATCH v3 6/8] mm/gup: return a huge page's full count from follow_page_mask() Rik van Riel
2026-08-11 2:51 ` [RFC PATCH v3 7/8] mm/gup: walk multiple PTEs per follow_page_pte() call Rik van Riel
2026-08-11 2:51 ` [RFC PATCH v3 8/8] mm/gup: batch contiguous same-folio PTEs into one refcount grab Rik van Riel
2026-08-12 11:41 ` [RFC PATCH v3 0/8] batch lookups in follow_page_mask() David Hildenbrand (Arm)
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