From: "David P. Reed" <dpreed@deepplum.com>
To: "Peter Xu" <peterx@redhat.com>
Cc: "James Houghton" <jthoughton@google.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
linux-mm@kvack.org, "Axel Rasmussen" <axelrasmussen@google.com>
Subject: Re: PROBLEM: userfaultfd REGISTER minor mode on MAP_PRIVATE range fails
Date: Tue, 16 Sep 2025 13:27:34 -0400 (EDT) [thread overview]
Message-ID: <1758043654.112619688@apps.rackspace.com> (raw)
In-Reply-To: <aMmMnfU-Koopc9mL@x1.local>
Than -
Just to clarify -
Looking at the man page for UFFDIO_API, there are two "feature bits" that indicate cases where "minor" handling is now supported, and can be enabled.
UFFD_FEATURE_MINOR_HUGETLBFS and UFFD_FEATURE_MINOR_SHMEM
In my reading of the documents, these seem to imply that before they were added as new features, that MAP_PRIVATE|MAP_ANONYMOUS mappings were supported, and that the "new" additions to the MINOR mode were just for HUGETLBFS and MAP_SHARED cases.
It seems odd that anonymous page faults and COW would not be handled, given that context.
Anyway, that's unclear in any of the documentation. This just adds to my last response where I explain my use case.
next prev parent reply other threads:[~2025-09-16 17:27 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-15 20:13 David P. Reed
2025-09-15 20:24 ` James Houghton
2025-09-15 22:58 ` David P. Reed
2025-09-16 0:31 ` James Houghton
2025-09-16 14:48 ` Peter Xu
2025-09-16 15:52 ` David P. Reed
2025-09-16 16:13 ` Peter Xu
2025-09-16 17:09 ` David P. Reed
2025-09-26 22:16 ` Peter Xu
2025-09-16 17:27 ` David P. Reed [this message]
2025-09-16 18:35 ` Axel Rasmussen
2025-09-16 19:10 ` James Houghton
2025-09-16 19:47 ` David P. Reed
2025-09-16 22:04 ` Axel Rasmussen
2025-09-26 22:00 ` Peter Xu
2025-09-16 19:52 ` David P. Reed
2025-09-17 16:13 ` Axel Rasmussen
2025-09-19 18:29 ` David P. Reed
2025-09-25 19:20 ` Axel Rasmussen
2025-09-27 18:45 ` David P. Reed
2025-09-29 5:30 ` James Houghton
2025-09-29 19:44 ` David P. Reed
2025-09-29 20:30 ` Peter Xu
2025-10-01 22:16 ` Axel Rasmussen
2025-10-17 21:07 ` David P. Reed
2025-09-16 15:37 ` David P. Reed
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