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McKenney" Cc: LKML , Frederic Weisbecker , "Eric W . Biederman" , Neeraj Upadhyay , Oleg Nesterov , Pengfei Xu , Boqun Feng , Lai Jiangshan , rcu@vger.kernel.org Subject: [PATCH 0/3] rcu-tasks: Fix race against exiting pid_ns Date: Fri, 25 Nov 2022 14:54:57 +0100 Message-Id: <20221125135500.1653800-1-frederic@kernel.org> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-Spam-Status: No, score=-7.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_HI, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1750476840409050820?= X-GMAIL-MSGID: =?utf-8?q?1750476840409050820?= Pengfei Xu has reported a deadlock involving calls to unshare(), perf_event_open() and clone3() calls. It requires CAP_SYS_ADMIN to reproduce (at least I don't see a way for a non privilege process to reproduce). See this thread for details: https://lore.kernel.org/all/Y3sOgrOmMQqPMItu@xpf.sh.intel.com/ And this document for the collaborative analysis with Boqun, Paul and Neeraj: https://docs.google.com/document/d/1hJxgiZ5TMZ4YJkdJPLAkRvq7sYQ-A7svgA8no6i-v8k The two first patches are small improvements. The fix is in the last patch. git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git rcu/dev HEAD: 45ef5a0a4be4e0db9eadcc86e8f346d34c62e744 Thanks, Frederic Reported-by: Pengfei Xu Signed-off-by: Frederic Weisbecker --- Frederic Weisbecker (3): rcu-tasks: Improve comments explaining tasks_rcu_exit_srcu purpose rcu-tasks: Remove preemption disablement around srcu_read_[un]lock() calls rcu-tasks: Fix synchronize_rcu_tasks() VS zap_pid_ns_processes() include/linux/rcupdate.h | 2 ++ kernel/pid_namespace.c | 17 +++++++++++++++ kernel/rcu/tasks.h | 55 ++++++++++++++++++++++++++++++++++++------------ 3 files changed, 60 insertions(+), 14 deletions(-)