From: Mike Rapoport <rppt@kernel.org>
To: Axel Rasmussen <axelrasmussen@google.com>
Cc: Alejandro Colomar <alx@kernel.org>, Peter Xu <peterx@redhat.com>,
linux-man@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 06/10] ioctl_userfaultfd.2: describe missing UFFDIO_API feature flags
Date: Mon, 9 Oct 2023 11:45:14 +0300 [thread overview]
Message-ID: <20231009084514.GJ3303@kernel.org> (raw)
In-Reply-To: <20230919190206.388896-7-axelrasmussen@google.com>
On Tue, Sep 19, 2023 at 12:02:02PM -0700, Axel Rasmussen wrote:
> Several new features have been added to the kernel recently, and the man
> page wasn't updated to describe these new features. So, add in
> descriptions of any missing features.
>
> Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
with a small nit below
> ---
> man2/ioctl_userfaultfd.2 | 23 +++++++++++++++++++++++
> 1 file changed, 23 insertions(+)
>
> diff --git a/man2/ioctl_userfaultfd.2 b/man2/ioctl_userfaultfd.2
> index e91a1dfc8..53b1f473f 100644
> --- a/man2/ioctl_userfaultfd.2
> +++ b/man2/ioctl_userfaultfd.2
> @@ -204,6 +204,13 @@ If this feature bit is set,
> .I uffd_msg.pagefault.feat.ptid
> will be set to the faulted thread ID for each page-fault message.
> .TP
> +.BR UFFD_FEATURE_PAGEFAULT_FLAG_WP " (since Linux 5.10)"
> +If this feature bit is set,
> +userfaultfd supports write-protect faults
> +for anonymous memory.
> +(Note that shmem / hugetlbfs support
> +is indicated by a separate feature.)
> +.TP
> .BR UFFD_FEATURE_MINOR_HUGETLBFS " (since Linux 5.13)"
> If this feature bit is set,
> the kernel supports registering userfaultfd ranges
> @@ -221,6 +228,22 @@ will be set to the exact page-fault address that was reported by the hardware,
> and will not mask the offset within the page.
> Note that old Linux versions might indicate the exact address as well,
> even though the feature bit is not set.
> +.TP
> +.BR UFFD_FEATURE_WP_HUGETLBFS_SHMEM " (since Linux 5.19)"
> +If this feature bit is set,
> +userfaultfd supports write-protect faults
> +for hugetlbfs and shmem / tmpfs memory.
> +.TP
> +.BR UFFD_FEATURE_WP_UNPOPULATED " (since Linux 6.4)"
> +If this feature bit is set,
> +the kernel will handle anonymous memory the same way as file memory,
> +by allowing the user to write-protect unpopulated ptes.
Nit: s/ptes/page table entries/
> +.TP
> +.BR UFFD_FEATURE_POISON " (since Linux 6.6)"
> +If this feature bit is set,
> +the kernel supports resolving faults with the
> +.B UFFDIO_POISON
> +ioctl.
> .PP
> The returned
> .I ioctls
> --
> 2.42.0.459.ge4e396fd5e-goog
>
>
--
Sincerely yours,
Mike.
next prev parent reply other threads:[~2023-10-09 8:46 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20230919190206.388896-1-axelrasmussen@google.com>
2023-09-19 19:01 ` [PATCH 01/10] userfaultfd.2: briefly mention two-step feature handshake process Axel Rasmussen
2023-09-25 23:26 ` Alejandro Colomar
2023-10-09 8:38 ` Mike Rapoport
2023-09-19 19:01 ` [PATCH 02/10] userfaultfd.2: reword to account for new fault resolution ioctls Axel Rasmussen
2023-09-25 23:29 ` Alejandro Colomar
2023-10-09 8:39 ` Mike Rapoport
2023-09-19 19:01 ` [PATCH 03/10] userfaultfd.2: comment on feature detection in the example program Axel Rasmussen
2023-09-25 23:32 ` Alejandro Colomar
2023-10-09 8:40 ` Mike Rapoport
2023-09-19 19:02 ` [PATCH 05/10] ioctl_userfaultfd.2: describe two-step feature handshake Axel Rasmussen
2023-09-25 23:44 ` Alejandro Colomar
2023-10-09 8:42 ` Mike Rapoport
2023-10-09 10:58 ` Alejandro Colomar
2023-09-19 19:02 ` [PATCH 06/10] ioctl_userfaultfd.2: describe missing UFFDIO_API feature flags Axel Rasmussen
2023-09-25 23:50 ` Alejandro Colomar
2023-10-09 8:45 ` Mike Rapoport [this message]
2023-10-09 10:49 ` Alejandro Colomar
2023-09-19 19:02 ` [PATCH 07/10] ioctl_userfaultfd.2: correct and update UFFDIO_API ioctl error codes Axel Rasmussen
2023-09-25 23:52 ` Alejandro Colomar
2023-10-09 8:49 ` Mike Rapoport
2023-10-09 11:01 ` Alejandro Colomar
2023-09-19 19:02 ` [PATCH 08/10] ioctl_userfaultfd.2: clarify the state of the uffdio_api structure on error Axel Rasmussen
2023-09-25 23:56 ` Alejandro Colomar
2023-09-26 17:58 ` Axel Rasmussen
2023-10-09 9:03 ` Mike Rapoport
2023-09-19 19:02 ` [PATCH 09/10] ioctl_userfaultfd.2: fix / update UFFDIO_REGISTER error code list Axel Rasmussen
2023-09-19 19:02 ` [PATCH 10/10] ioctl_userfaultfd.2: document new UFFDIO_POISON ioctl Axel Rasmussen
2023-10-09 9:09 ` Mike Rapoport
2023-10-10 17:13 ` Axel Rasmussen
[not found] ` <20230919190206.388896-5-axelrasmussen@google.com>
2023-09-25 23:37 ` [PATCH 04/10] ioctl_userfaultfd.2: fix a few trivial mistakes Alejandro Colomar
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