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[99.241.198.116]) by smtp.gmail.com with ESMTPSA id d13-20020a5d964d000000b00665714766a2sm2677998ios.47.2022.06.03.10.34.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 03 Jun 2022 10:34:21 -0700 (PDT) Date: Fri, 3 Jun 2022 13:34:19 -0400 From: Peter Xu To: Alejandro Colomar Cc: linux-kernel@vger.kernel.org, linux-man@vger.kernel.org, linux-mm@kvack.org, Axel Rasmussen , Andrea Arcangeli , Nadav Amit , Andrew Morton Subject: Re: [PATCH 1/2] userfaultfd.2: Add section for UFFD_USER_MODE_ONLY Message-ID: References: <20220531011157.46868-1-peterx@redhat.com> <20220531011157.46868-2-peterx@redhat.com> MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit X-Rspam-User: Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=PsGEHxom; dmarc=pass (policy=none) header.from=redhat.com; spf=none (imf29.hostedemail.com: domain of peterx@redhat.com has no SPF policy when checking 170.10.129.124) smtp.mailfrom=peterx@redhat.com X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 2AD55120005 X-Stat-Signature: n4xr64r1ddkywfy3m3q94mtue84i6fg9 X-HE-Tag: 1654277650-210736 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Jun 03, 2022 at 07:11:05PM +0200, Alejandro Colomar wrote: > Hi Peter, > > On 5/31/22 03:11, Peter Xu wrote: > > Add a paragraph for UFFD_USER_MODE_ONLY flag that was introduced in > > Linux 5.11. > > > > Signed-off-by: Peter Xu > > See some minor comments below. > > Cheers, > > Alex > > > --- > > man2/userfaultfd.2 | 14 ++++++++++++-- > > 1 file changed, 12 insertions(+), 2 deletions(-) > > > > diff --git a/man2/userfaultfd.2 b/man2/userfaultfd.2 > > index cee7c01d2..0928a76d2 100644 > > --- a/man2/userfaultfd.2 > > +++ b/man2/userfaultfd.2 > > @@ -29,8 +29,9 @@ > > userfaultfd \- create a file descriptor for handling page faults in user space > > .SH SYNOPSIS > > .nf > > -.BR "#include " " /* Definition of " O_* " constants */" > > -.BR "#include " " /* Definition of " SYS_* " constants */" > > +.BR "#include " " /* Definition of " O_* " constants */" > > +.BR "#include " " /* Definition of " SYS_* " constants */" > > +.BR "#include " " /* Definition of " UFFD_* " constants */" > > .B #include > > .PP > > .BI "int syscall(SYS_userfaultfd, int " flags ); > > @@ -76,6 +77,15 @@ See the description of the > > .BR O_NONBLOCK > > flag in > > .BR open (2). > > +.TP > > +.BR UFFD_USER_MODE_ONLY > > > s/BR/B/ > > see groff_man(7): > > [ > [...] > > .B [text] > Set text in bold. If the macro is given no argu‐ > ments, the text of the next input line is set in > bold. > > [...] > > .BR bold‐text roman‐text ... > Set each argument in bold and roman, alternately. > ] > > > +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 > > +.BR SIGBUS > > s/BR/B/ Thanks Alex, I'll fix and repost the patchset soon. -- Peter Xu