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[174.91.135.175]) by smtp.gmail.com with ESMTPSA id i93sm11373613qtd.48.2021.03.23.08.17.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 23 Mar 2021 08:17:10 -0700 (PDT) Date: Tue, 23 Mar 2021 11:17:09 -0400 From: Peter Xu To: Mike Rapoport Cc: linux-man@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrea Arcangeli , Mike Rapoport , Axel Rasmussen , Alejandro Colomar , Michael Kerrisk , Nadav Amit , Andrew Morton Subject: Re: [PATCH v4 1/4] userfaultfd.2: Add UFFD_FEATURE_THREAD_ID docs Message-ID: <20210323151709.GE6486@xz-x1> References: <20210322220848.52162-1-peterx@redhat.com> <20210322220848.52162-2-peterx@redhat.com> MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=peterx@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Stat-Signature: mruisjqc877o75gggynw3jfutbgxd6i9 X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: C5D629001160 Received-SPF: none (redhat.com>: No applicable sender policy available) receiver=imf19; identity=mailfrom; envelope-from=""; helo=us-smtp-delivery-124.mimecast.com; client-ip=216.205.24.124 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1616512633-53759 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 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 > > --- > > 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