[PATCH 0/3] rcu-tasks: Fix race against exiting pid_ns

From: Frederic Weisbecker <frederic@kernel.org>
To: "Paul E . McKenney" <paulmck@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Frederic Weisbecker <frederic@kernel.org>,
	"Eric W . Biederman" <ebiederm@xmission.com>,
	Neeraj Upadhyay <quic_neeraju@quicinc.com>,
	Oleg Nesterov <oleg@redhat.com>,
	Pengfei Xu <pengfei.xu@intel.com>,
	Boqun Feng <boqun.feng@gmail.com>,
	Lai Jiangshan <jiangshanlai@gmail.com>,
	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	[thread overview]
Message-ID: <20221125135500.1653800-1-frederic@kernel.org> (raw)

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
---

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(-)