This is a note to let you know that I've just added the patch titled
rcu-tasks: Mark ->trc_reader_nesting data races
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
rcu-tasks-mark-trc_reader_nesting-data-races.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From stable-owner@xxxxxxxxxxxxxxx Sat Jul 15 02:47:26 2023
From: "Joel Fernandes (Google)" <joel@xxxxxxxxxxxxxxxxx>
Date: Sat, 15 Jul 2023 00:47:09 +0000
Subject: rcu-tasks: Mark ->trc_reader_nesting data races
To: stable@xxxxxxxxxxxxxxx
Cc: "Joel Fernandes (Google)" <joel@xxxxxxxxxxxxxxxxx>, "Paul E . McKenney" <paulmck@xxxxxxxxxx>
Message-ID: <20230715004711.2938489-2-joel@xxxxxxxxxxxxxxxxx>
From: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
[ Upstream commit bdb0cca0d11060fce8a8a44588ac1470c25d62bc ]
There are several ->trc_reader_nesting data races that are too
low-probability for KCSAN to notice, but which will happen sooner or
later. This commit therefore marks these accesses, and comments one
that cannot race.
Cc: <stable@xxxxxxxxxxxxxxx> # 5.10.x
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/rcu/tasks.h | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -848,7 +848,7 @@ static void trc_read_check_handler(void
// If the task is not in a read-side critical section, and
// if this is the last reader, awaken the grace-period kthread.
- if (likely(!t->trc_reader_nesting)) {
+ if (likely(!READ_ONCE(t->trc_reader_nesting))) {
if (WARN_ON_ONCE(atomic_dec_and_test(&trc_n_readers_need_end)))
wake_up(&trc_wait);
// Mark as checked after decrement to avoid false
@@ -857,7 +857,7 @@ static void trc_read_check_handler(void
goto reset_ipi;
}
// If we are racing with an rcu_read_unlock_trace(), try again later.
- if (unlikely(t->trc_reader_nesting < 0)) {
+ if (unlikely(READ_ONCE(t->trc_reader_nesting) < 0)) {
if (WARN_ON_ONCE(atomic_dec_and_test(&trc_n_readers_need_end)))
wake_up(&trc_wait);
goto reset_ipi;
@@ -904,6 +904,7 @@ static bool trc_inspect_reader(struct ta
n_heavy_reader_ofl_updates++;
in_qs = true;
} else {
+ // The task is not running, so C-language access is safe.
in_qs = likely(!t->trc_reader_nesting);
}
@@ -936,7 +937,7 @@ static void trc_wait_for_one_reader(stru
// The current task had better be in a quiescent state.
if (t == current) {
t->trc_reader_checked = true;
- WARN_ON_ONCE(t->trc_reader_nesting);
+ WARN_ON_ONCE(READ_ONCE(t->trc_reader_nesting));
return;
}
@@ -1046,7 +1047,7 @@ static void show_stalled_task_trace(stru
".I"[READ_ONCE(t->trc_ipi_to_cpu) > 0],
".i"[is_idle_task(t)],
".N"[cpu > 0 && tick_nohz_full_cpu(cpu)],
- t->trc_reader_nesting,
+ READ_ONCE(t->trc_reader_nesting),
" N"[!!t->trc_reader_special.b.need_qs],
cpu);
sched_show_task(t);
@@ -1141,7 +1142,7 @@ static void rcu_tasks_trace_postgp(struc
static void exit_tasks_rcu_finish_trace(struct task_struct *t)
{
WRITE_ONCE(t->trc_reader_checked, true);
- WARN_ON_ONCE(t->trc_reader_nesting);
+ WARN_ON_ONCE(READ_ONCE(t->trc_reader_nesting));
WRITE_ONCE(t->trc_reader_nesting, 0);
if (WARN_ON_ONCE(READ_ONCE(t->trc_reader_special.b.need_qs)))
rcu_read_unlock_trace_special(t, 0);
Patches currently in stable-queue which might be from stable-owner@xxxxxxxxxxxxxxx are
queue-5.10/rcu-tasks-simplify-trc_read_check_handler-atomic-operations.patch
queue-5.10/netfilter-nf_tables-fix-chain-binding-transaction-logic.patch
queue-5.10/netfilter-nf_tables-drop-map-element-references-from-preparation-phase.patch
queue-5.10/netfilter-nf_tables-fix-scheduling-while-atomic-splat.patch
queue-5.10/netfilter-nf_tables-reject-unbound-anonymous-set-before-commit-phase.patch
queue-5.10/netfilter-nf_tables-use-net_generic-infra-for-transaction-data.patch
queue-5.10/netfilter-nftables-rename-set-element-data-activation-deactivation-functions.patch
queue-5.10/netfilter-nf_tables-incorrect-error-path-handling-with-nft_msg_newrule.patch
queue-5.10/rcu-tasks-mark-trc_reader_nesting-data-races.patch
queue-5.10/netfilter-nf_tables-reject-unbound-chain-set-before-commit-phase.patch
queue-5.10/rcu-tasks-mark-trc_reader_special.b.need_qs-data-races.patch
queue-5.10/netfilter-nf_tables-add-rescheduling-points-during-loop-detection-walks.patch
queue-5.10/netfilter-nf_tables-add-nft_trans_prepare_error-to-deal-with-bound-set-chain.patch
queue-5.10/netfilter-nf_tables-unbind-non-anonymous-set-if-rule-construction-fails.patch
