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@xxxxxxxxxxxxxxxx/ 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(-)
