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[99.241.198.116]) by smtp.gmail.com with ESMTPSA id s6-20020a02c7c6000000b0032be3784b9bsm3158234jao.117.2022.05.30.18.12.00 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Mon, 30 May 2022 18:12:01 -0700 (PDT) From: Peter Xu To: linux-kernel@vger.kernel.org, linux-man@vger.kernel.org, linux-mm@kvack.org Cc: Alejandro Colomar , Michael Kerrisk , Axel Rasmussen , Andrea Arcangeli , peterx@redhat.com, Nadav Amit , Andrew Morton Subject: [PATCH 1/2] userfaultfd.2: Add section for UFFD_USER_MODE_ONLY Date: Mon, 30 May 2022 21:11:56 -0400 Message-Id: <20220531011157.46868-2-peterx@redhat.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20220531011157.46868-1-peterx@redhat.com> References: <20220531011157.46868-1-peterx@redhat.com> MIME-Version: 1.0 Content-type: text/plain Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add a paragraph for UFFD_USER_MODE_ONLY flag that was introduced in Linux 5.11. Signed-off-by: Peter Xu --- 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 +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 +signal will be delivered. .PP When the last file descriptor referring to a userfaultfd object is closed, all memory ranges that were registered with the object are unregistered -- 2.32.0