linux-kernel - Re: [PATCH v4 1/4] userfaultfd.2: Add UFFD_FEATURE_THREAD

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Message-ID: <20210323151709.GE6486@xz-x1>
Date:   Tue, 23 Mar 2021 11:17:09 -0400
From:   Peter Xu <peterx@...hat.com>
To:     Mike Rapoport <rppt@...ux.ibm.com>
Cc:     linux-man@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, Andrea Arcangeli <aarcange@...hat.com>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        Axel Rasmussen <axelrasmussen@...gle.com>,
        Alejandro Colomar <alx.manpages@...il.com>,
        Michael Kerrisk <mtk.manpages@...il.com>,
        Nadav Amit <nadav.amit@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v4 1/4] userfaultfd.2: Add UFFD_FEATURE_THREAD_ID docs

On Tue, Mar 23, 2021 at 10:27:34AM +0200, Mike Rapoport wrote:
> On Mon, Mar 22, 2021 at 06:08:45PM -0400, Peter Xu wrote:
> > UFFD_FEATURE_THREAD_ID is supported since Linux 4.14.
> > 
> > Signed-off-by: Peter Xu <peterx@...hat.com>
> > ---
> >  man2/userfaultfd.2 | 13 +++++++++++++
> >  1 file changed, 13 insertions(+)
> > 
> > diff --git a/man2/userfaultfd.2 b/man2/userfaultfd.2
> > index e7dc9f813..555e37409 100644
> > --- a/man2/userfaultfd.2
> > +++ b/man2/userfaultfd.2
> > @@ -77,6 +77,13 @@ When the last file descriptor referring to a userfaultfd object is closed,
> >  all memory ranges that were registered with the object are unregistered
> >  and unread events are flushed.
> >  .\"
> > +.PP
> > +Since Linux 4.14, userfaultfd page fault message can selectively embed faulting
> > +thread ID information into the fault message.
> > +One needs to enable this feature explicitly using the
> > +.BR UFFD_FEATURE_THREAD_ID
> > +feature bit when initializing the userfaultfd context.
> > +By default, thread ID reporting is diabled.
> 
> 				     ^ disabled :)

Right! :)

I'll wait for another round of Alex's review before reposting.

Thanks,

-- 
Peter Xu