Re: [PATCH v3 2/3] ioctl_userfaultfd.2: fix / update UFFDIO_REGISTER error code list

Alejandro Colomar
2023-10-17T23:23:58Z

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Hi Axel, Mike,

On Tue, Oct 17, 2023 at 04:01:09PM -0700, Axel Rasmussen wrote:
> The list of error codes in the man page was out of date with respect to
> the current state of the kernel. Some errors were partially /
> incorrectly described.
>
> Update the error code listing, so it matches the current state of the
> kernel, and correctly describes all the errors.
>
> Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>

I'll wait a bit before applying this one, in case Mike (or Peter) want
to review it.

The other two, you can find them here, as usual:
<https://www.alejandro-colomar.es/src/alx/linux/man-pages/man-pages.git/commit/?h=contrib&id=9ae03d21383151794b118ac8dd98b4d6e26c9689>
<https://www.alejandro-colomar.es/src/alx/linux/man-pages/man-pages.git/commit/?h=contrib&id=5f1acc81e55540d1276977e66d64649c6ca7b58b>

And BTW, while running `make lint build check`, I caught some accidents
from a previous patch from yours:
<https://www.alejandro-colomar.es/src/alx/linux/man-pages/man-pages.git/commit/?h=contrib&id=bf8647d1d82205934776b474fe89e5f30e03ad25>

Cheers,
Alex

> ---
> man2/ioctl_userfaultfd.2 | 33 +++++++++++++++++++--------------
> 1 file changed, 19 insertions(+), 14 deletions(-)
>
> diff --git a/man2/ioctl_userfaultfd.2 b/man2/ioctl_userfaultfd.2
> index 82aee667c..40528001e 100644
> --- a/man2/ioctl_userfaultfd.2
> +++ b/man2/ioctl_userfaultfd.2
> @@ -413,8 +413,6 @@ On error, \-1 is returned and
> .I errno
> is set to indicate the error.
> Possible errors include:
> -.\" FIXME Is the following error list correct?
> -.\"
> .TP
> .B EBUSY
> A mapping in the specified range is registered with another
> @@ -433,21 +431,28 @@ field; or the
> field was zero.
> .TP
> .B EINVAL
> -There is no mapping in the specified address range.
> -.TP
> -.B EINVAL
> -.I range.start
> +The specified address range was invalid.
> +More specifically,
> +no mapping exists in the given range,
> +or the mapping that exists there is invalid
> +(e.g. unsupported type of memory),
> +or the range values
> +.RI ( range.start
> +or
> +.IR range.len )
> +are not multiples of the relevant page size,
> or
> .I range.len
> -is not a multiple of the system page size; or,
> -.I range.len
> -is zero; or these fields are otherwise invalid.
> +is zero.
> .TP
> -.B EINVAL
> -There as an incompatible mapping in the specified address range.
> -.\" Mike Rapoport:
> -.\" ENOMEM if the process is exiting and the
> -.\" mm_struct has gone by the time userfault grabs it.
> +.B ENOMEM
> +The process is exiting,
> +and its address space has already been torn down
> +when userfaultfd attempts to reference it.
> +.TP
> +.B EPERM
> +The userfaultfd would allow writing to a file backing the mapping,
> +but the calling process lacks such write permissions.
> .SS UFFDIO_UNREGISTER
> (Since Linux 4.3.)
> Unregister a memory address range from userfaultfd.
> --
> 2.42.0.655.g421f12c284-goog
>

--
<https://www.alejandro-colomar.es/>

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