diff options
| author | Frederic Weisbecker <frederic@kernel.org> | 2024-04-25 16:24:04 +0200 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2024-06-03 17:30:08 -0700 |
| commit | 9855c37edf0009cc276cecfee09f7e76e2380212 (patch) | |
| tree | beb98308f9cc5f960668a7ca7522a05ddc2660f5 /kernel/rcu | |
| parent | 1613e604df0cd359cf2a7fbd9be7a0bcfacfabd0 (diff) | |
Revert "rcu-tasks: Fix synchronize_rcu_tasks() VS zap_pid_ns_processes()"
This reverts commit 28319d6dc5e2ffefa452c2377dd0f71621b5bff0. The race
it fixed was subject to conditions that don't exist anymore since:
1612160b9127 ("rcu-tasks: Eliminate deadlocks involving do_exit() and RCU tasks")
This latter commit removes the use of SRCU that used to cover the
RCU-tasks blind spot on exit between the tasklist's removal and the
final preemption disabling. The task is now placed instead into a
temporary list inside which voluntary sleeps are accounted as RCU-tasks
quiescent states. This would disarm the deadlock initially reported
against PID namespace exit.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tasks.h | 16 |
1 files changed, 3 insertions, 13 deletions
diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h index e1bf33018e6d..4dc56b6e27c0 100644 --- a/kernel/rcu/tasks.h +++ b/kernel/rcu/tasks.h @@ -858,7 +858,7 @@ static void rcu_tasks_wait_gp(struct rcu_tasks *rtp) // not know to synchronize with this RCU Tasks grace period) have // completed exiting. The synchronize_rcu() in rcu_tasks_postgp() // will take care of any tasks stuck in the non-preemptible region -// of do_exit() following its call to exit_tasks_rcu_stop(). +// of do_exit() following its call to exit_tasks_rcu_finish(). // check_all_holdout_tasks(), repeatedly until holdout list is empty: // Scans the holdout list, attempting to identify a quiescent state // for each task on the list. If there is a quiescent state, the @@ -1220,7 +1220,7 @@ void exit_tasks_rcu_start(void) * Remove the task from the "yet another list" because do_exit() is now * non-preemptible, allowing synchronize_rcu() to wait beyond this point. */ -void exit_tasks_rcu_stop(void) +void exit_tasks_rcu_finish(void) { unsigned long flags; struct rcu_tasks_percpu *rtpcp; @@ -1231,22 +1231,12 @@ void exit_tasks_rcu_stop(void) raw_spin_lock_irqsave_rcu_node(rtpcp, flags); list_del_init(&t->rcu_tasks_exit_list); raw_spin_unlock_irqrestore_rcu_node(rtpcp, flags); -} -/* - * Contribute to protect against tasklist scan blind spot while the - * task is exiting and may be removed from the tasklist. See - * corresponding synchronize_srcu() for further details. - */ -void exit_tasks_rcu_finish(void) -{ - exit_tasks_rcu_stop(); - exit_tasks_rcu_finish_trace(current); + exit_tasks_rcu_finish_trace(t); } #else /* #ifdef CONFIG_TASKS_RCU */ void exit_tasks_rcu_start(void) { } -void exit_tasks_rcu_stop(void) { } void exit_tasks_rcu_finish(void) { exit_tasks_rcu_finish_trace(current); } #endif /* #else #ifdef CONFIG_TASKS_RCU */ |