Re: [PATCH v2 0/2] userfaultfd.2: Update to latest

[Peter Xu <peterx@redhat.com>]

On Mon, Jun 06, 2022 at 08:52:25PM +0200, Alejandro Colomar wrote:
> Hi Peter,

Hi, Alex,

> 
> On 6/3/22 19:37, Peter Xu wrote:
> > v2:
> > - Use semantic newlines always in patch 1 [Alex]
> > - Fix s/.BR/.B/ in patch 2 [Alex]
> > - Rebased to http://www.alejandro-colomar.es/src/alx/linux/man-pages/man-pages.git
> > 
> > Add the two missing pieces till latest 5.19-rc1: the UFFD_USER_MODE_ONLY
> > flag, and also the recent wr-protect support on shmem and hugetlbfs.
> > 
> > Please review, thanks.
> > 
> > Peter Xu (2):
> >    userfaultfd.2: Add section for UFFD_USER_MODE_ONLY
> >    userfaultfd.2: Update on write-protection support
> > 
> >   man2/userfaultfd.2 | 23 ++++++++++++++++++-----
> >   1 file changed, 18 insertions(+), 5 deletions(-)
> > 
> 
> 
> I think the patch below would improve a little bit the wording (and
> newlines).  I still have a bit of trouble understanding "When a
> kernel-originated fault was triggered on the registered range with this
> userfaultfd".  Did you maybe mean "range registered" instead of "registered
> range"?

Since I'm not a native speaker I don't immediately see the difference
between the two..  What I wanted to express is all the memory ranges that
we registered with UFFDIO_REGISTER ioctl, and further it was trying to
describe what the kernel will do when there're any page faults that were
triggered upon those ranges from a kernel context.

It's always challenging for me to grasp how you prefer the newlines are
made, but anyway below changes looks good to me.  Thanks,

> 
> Thanks,
> 
> Alex
> 
> 
> diff --git a/man2/userfaultfd.2 b/man2/userfaultfd.2
> index 9b5ec0358..0c0a4f687 100644
> --- a/man2/userfaultfd.2
> +++ b/man2/userfaultfd.2
> @@ -62,11 +62,11 @@ flag in
>  .BR open (2).
>  .TP
>  .B UFFD_USER_MODE_ONLY
> -This is an userfaultfd specific flag that was introduced since Linux 5.11.
> -When set, the userfaultfd object will only be able to handle page faults
> -originated from the userspace on the registered regions.
> -When a kernel originated fault was triggered on the registered range with
> -this userfaultfd, a
> +This is an userfaultfd-specific flag that was introduced in Linux 5.11.
> +When set, the userfaultfd object will only be able to handle
> +page faults originated from the user space on the registered regions.
> +When a kernel-originated fault was triggered
> +on the registered range with this userfaultfd, a
>  .B SIGBUS
>  signal will be delivered.
>  .PP
> @@ -277,8 +277,9 @@ ioctl against the feature bit
>  .B UFFD_FEATURE_PAGEFAULT_FLAG_WP
>  before using this feature.
>  .PP
> -Since Linux 5.19, the write-protection mode was also supported on shmem and
> hugetlbfs
> -memory types.
> +Since Linux 5.19,
> +the write-protection mode was also supported on
> +shmem and hugetlbfs memory types.
>  It can be detected with the feature bit
>  .BR UFFD_FEATURE_WP_HUGETLBFS_SHMEM .
>  .PP
> 
> 
> -- 
> Alejandro Colomar
> <http://www.alejandro-colomar.es/>




-- 
Peter Xu