6.16-stable review patch. If anyone has any objections, please let me know.
------------------
From: Zqiang qiang.zhang1211@gmail.com
[ Upstream commit 8d71351d88e478d3c4e945e3218e97ec677fd807 ]
For built with CONFIG_PREEMPT_RT=y kernels, running rcutorture tests resulted in the following splat:
[ 68.797425] rcutorture_one_extend_check during change: Current 0x1 To add 0x1 To remove 0x0 preempt_count() 0x0 [ 68.797533] WARNING: CPU: 2 PID: 512 at kernel/rcu/rcutorture.c:1993 rcutorture_one_extend_check+0x419/0x560 [rcutorture] [ 68.797601] Call Trace: [ 68.797602] <TASK> [ 68.797619] ? lockdep_softirqs_off+0xa5/0x160 [ 68.797631] rcutorture_one_extend+0x18e/0xcc0 [rcutorture 2466dbd2ff34dbaa36049cb323a80c3306ac997c] [ 68.797646] ? local_clock+0x19/0x40 [ 68.797659] rcu_torture_one_read+0xf0/0x280 [rcutorture 2466dbd2ff34dbaa36049cb323a80c3306ac997c] [ 68.797678] ? __pfx_rcu_torture_one_read+0x10/0x10 [rcutorture 2466dbd2ff34dbaa36049cb323a80c3306ac997c] [ 68.797804] ? __pfx_rcu_torture_timer+0x10/0x10 [rcutorture 2466dbd2ff34dbaa36049cb323a80c3306ac997c] [ 68.797815] rcu-torture: rcu_torture_reader task started [ 68.797824] rcu-torture: Creating rcu_torture_reader task [ 68.797824] rcu_torture_reader+0x238/0x580 [rcutorture 2466dbd2ff34dbaa36049cb323a80c3306ac997c] [ 68.797836] ? kvm_sched_clock_read+0x15/0x30
Disable BH does not change the SOFTIRQ corresponding bits in preempt_count() for RT kernels, this commit therefore use softirq_count() to check the if BH is disabled.
Reviewed-by: Paul E. McKenney paulmck@kernel.org Signed-off-by: Zqiang qiang.zhang1211@gmail.com Signed-off-by: Joel Fernandes joelagnelf@nvidia.com Signed-off-by: Neeraj Upadhyay (AMD) neeraj.upadhyay@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/rcu/rcutorture.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index 70ec0f21abc3..1d4635f8bb43 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -464,7 +464,7 @@ rcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp) !(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms))) { started = cur_ops->get_gp_seq(); ts = rcu_trace_clock_local(); - if (preempt_count() & (SOFTIRQ_MASK | HARDIRQ_MASK)) + if ((preempt_count() & HARDIRQ_MASK) || softirq_count()) longdelay_ms = 5; /* Avoid triggering BH limits. */ mdelay(longdelay_ms); rtrsp->rt_delay_ms = longdelay_ms; @@ -1930,7 +1930,7 @@ static void rcutorture_one_extend_check(char *s, int curstate, int new, int old, return;
WARN_ONCE((curstate & (RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH)) && - !(preempt_count() & SOFTIRQ_MASK), ROEC_ARGS); + !softirq_count(), ROEC_ARGS); WARN_ONCE((curstate & (RCUTORTURE_RDR_PREEMPT | RCUTORTURE_RDR_SCHED)) && !(preempt_count() & PREEMPT_MASK), ROEC_ARGS); WARN_ONCE(cur_ops->readlock_nesting && @@ -1944,7 +1944,7 @@ static void rcutorture_one_extend_check(char *s, int curstate, int new, int old,
WARN_ONCE(cur_ops->extendables && !(curstate & (RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH)) && - (preempt_count() & SOFTIRQ_MASK), ROEC_ARGS); + softirq_count(), ROEC_ARGS);
/* * non-preemptible RCU in a preemptible kernel uses preempt_disable() @@ -1965,6 +1965,9 @@ static void rcutorture_one_extend_check(char *s, int curstate, int new, int old, if (!IS_ENABLED(CONFIG_PREEMPT_RCU)) mask |= RCUTORTURE_RDR_PREEMPT | RCUTORTURE_RDR_SCHED;
+ if (IS_ENABLED(CONFIG_PREEMPT_RT) && softirq_count()) + mask |= RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH; + WARN_ONCE(cur_ops->readlock_nesting && !(curstate & mask) && cur_ops->readlock_nesting() > 0, ROEC_ARGS); }