On Tue, Nov 29, 2022 at 06:48:34AM -0800, Paul E. McKenney wrote: > On Tue, Nov 29, 2022 at 10:55:00AM +0100, Frederic Weisbecker wrote: > > On Mon, Nov 28, 2022 at 04:22:40PM -0800, Paul E. McKenney wrote: > > > On Fri, Nov 25, 2022 at 02:54:57PM +0100, Frederic Weisbecker wrote: > > > > 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 > > > > > > Hearing no objections, queued for further review and testing. > > > > > > And thank you very much! That race between synchronize_rcu_tasks() and > > > zap_pid_ns_processes() certainly was more than a bit on the non-trivial > > > side. Good show!!! > > > > Thanks! > > > > Also please replace the last patch with the following to fix > > a !CONFIG_RCU_TASKS issue: > > Like this? ;-) > > a0c355bbdfee ("squash! rcu-tasks: Fix synchronize_rcu_tasks() VS zap_pid_ns_processes()") You got it! :)
