[ANNOUNCE] v5.14-rc7-rt13

From: Sebastian Andrzej Siewior
Date: Mon Aug 23 2021 - 12:04:13 EST

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Dear RT folks!

I'm pleased to announce the v5.14-rc7-rt13 patch set.

Changes since v5.14-rc7-rt12:

- A change to ww_mutex code to avoid a crash in non-RT. Reported by
Guenter Roeck.

- The patch for rcu-torture has been updated to address review
comments.

Known issues
- netconsole triggers WARN.

- The "Memory controller" (CONFIG_MEMCG) has been disabled.

- A RCU and ARM64 warning has been fixed by Valentin Schneider. It is
still not clear if the RCU related change is correct.

- Clark Williams reported issues in i915 (execlists_dequeue_irq())

- Clark Williams reported issues with kcov enabled.

- Valentin Schneider reported a few splats on ARM64, see
https://https://lkml.kernel.org/r/.kernel.org/lkml/20210810134127.1394269-1-valentin.schneider@xxxxxxx/

The delta patch against v5.14-rc7-rt12 is appended below and can be found here:

https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.14/incr/patch-5.14-rc7-rt12-rt13.patch.xz

You can get this release via the git tree at:

git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git v5.14-rc7-rt13

The RT patch against v5.14-rc7 can be found here:

https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.14/older/patch-5.14-rc7-rt13.patch.xz

The split quilt queue is available at:

https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.14/older/patches-5.14-rc7-rt13.tar.xz

Sebastian

diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
index 05b68931622d1..2c70213934cd4 100644
--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -614,7 +614,7 @@ __mutex_lock_common(struct mutex *lock, unsigned int state, unsigned int subclas

debug_mutex_lock_common(lock, &waiter);
waiter.task = current;
- if (ww_ctx)
+ if (use_ww_ctx)
waiter.ww_ctx = ww_ctx;

lock_contended(&lock->dep_map, ip);
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index f01368a05374d..d2ef535530b10 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -61,13 +61,10 @@ MODULE_AUTHOR("Paul E. McKenney <paulmck@xxxxxxxxxxxxx> and Josh Triplett <josh@
#define RCUTORTURE_RDR_RBH 0x08 /* ... rcu_read_lock_bh(). */
#define RCUTORTURE_RDR_SCHED 0x10 /* ... rcu_read_lock_sched(). */
#define RCUTORTURE_RDR_RCU 0x20 /* ... entering another RCU reader. */
-#define RCUTORTURE_RDR_ATOM_BH 0x40 /* ... disabling bh while atomic */
-#define RCUTORTURE_RDR_ATOM_RBH 0x80 /* ... RBH while atomic */
-#define RCUTORTURE_RDR_NBITS 8 /* Number of bits defined above. */
+#define RCUTORTURE_RDR_NBITS 6 /* Number of bits defined above. */
#define RCUTORTURE_MAX_EXTEND \
(RCUTORTURE_RDR_BH | RCUTORTURE_RDR_IRQ | RCUTORTURE_RDR_PREEMPT | \
- RCUTORTURE_RDR_RBH | RCUTORTURE_RDR_SCHED | \
- RCUTORTURE_RDR_ATOM_BH | RCUTORTURE_RDR_ATOM_RBH)
+ RCUTORTURE_RDR_RBH | RCUTORTURE_RDR_SCHED)
#define RCUTORTURE_RDR_MAX_LOOPS 0x7 /* Maximum reader extensions. */
/* Must be power of two minus one. */
#define RCUTORTURE_RDR_MAX_SEGS (RCUTORTURE_RDR_MAX_LOOPS + 3)
@@ -1432,11 +1429,7 @@ static void rcutorture_one_extend(int *readstate, int newstate,
WARN_ON_ONCE((idxold >> RCUTORTURE_RDR_SHIFT) > 1);
rtrsp->rt_readstate = newstate;

- /*
- * First, put new protection in place to avoid critical-section gap.
- * Disable preemption around the ATOM disables to ensure that
- * in_atomic() is true.
- */
+ /* First, put new protection in place to avoid critical-section gap. */
if (statesnew & RCUTORTURE_RDR_BH)
local_bh_disable();
if (statesnew & RCUTORTURE_RDR_RBH)
@@ -1447,29 +1440,18 @@ static void rcutorture_one_extend(int *readstate, int newstate,
preempt_disable();
if (statesnew & RCUTORTURE_RDR_SCHED)
rcu_read_lock_sched();
- preempt_disable();
- if (statesnew & RCUTORTURE_RDR_ATOM_BH)
- local_bh_disable();
- if (statesnew & RCUTORTURE_RDR_ATOM_RBH)
- rcu_read_lock_bh();
- preempt_enable();
if (statesnew & RCUTORTURE_RDR_RCU)
idxnew = cur_ops->readlock() << RCUTORTURE_RDR_SHIFT;

/*
* Next, remove old protection, in decreasing order of strength
* to avoid unlock paths that aren't safe in the stronger
- * context. Disable preemption around the ATOM enables in
- * case the context was only atomic due to IRQ disabling.
+ * context. Namely: BH can not be enabled with disabled interrupts.
+ * Additionally PREEMPT_RT requires that BH is enabled in preemptible
+ * context.
*/
- preempt_disable();
if (statesold & RCUTORTURE_RDR_IRQ)
local_irq_enable();
- if (statesold & RCUTORTURE_RDR_ATOM_BH)
- local_bh_enable();
- if (statesold & RCUTORTURE_RDR_ATOM_RBH)
- rcu_read_unlock_bh();
- preempt_enable();
if (statesold & RCUTORTURE_RDR_PREEMPT)
preempt_enable();
if (statesold & RCUTORTURE_RDR_SCHED)
@@ -1478,7 +1460,6 @@ static void rcutorture_one_extend(int *readstate, int newstate,
local_bh_enable();
if (statesold & RCUTORTURE_RDR_RBH)
rcu_read_unlock_bh();
-
if (statesold & RCUTORTURE_RDR_RCU) {
bool lockit = !statesnew && !(torture_random(trsp) & 0xffff);

@@ -1523,10 +1504,7 @@ rcutorture_extend_mask(int oldmask, struct torture_random_state *trsp)
unsigned long randmask2 = randmask1 >> 3;
unsigned long preempts = RCUTORTURE_RDR_PREEMPT | RCUTORTURE_RDR_SCHED;
unsigned long preempts_irq = preempts | RCUTORTURE_RDR_IRQ;
- unsigned long nonatomic_bhs = RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH;
- unsigned long atomic_bhs = RCUTORTURE_RDR_ATOM_BH |
- RCUTORTURE_RDR_ATOM_RBH;
- unsigned long tmp;
+ unsigned long bhs = RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH;

WARN_ON_ONCE(mask >> RCUTORTURE_RDR_SHIFT);
/* Mostly only one bit (need preemption!), sometimes lots of bits. */
@@ -1538,9 +1516,8 @@ rcutorture_extend_mask(int oldmask, struct torture_random_state *trsp)
/*
* Can't enable bh w/irq disabled.
*/
- tmp = atomic_bhs | nonatomic_bhs;
if (mask & RCUTORTURE_RDR_IRQ)
- mask |= oldmask & tmp;
+ mask |= oldmask & bhs;

/*
* Ideally these sequences would be detected in debug builds
@@ -1548,30 +1525,11 @@ rcutorture_extend_mask(int oldmask, struct torture_random_state *trsp)
* them on non-RT.
*/
if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
- /*
- * Can't disable bh in atomic context if bh was already
- * disabled by another task on the same CPU. Instead of
- * attempting to track this, just avoid disabling bh in atomic
- * context.
- */
- mask &= ~atomic_bhs;
- /*
- * Can't release the outermost rcu lock in an irq disabled
- * section without preemption also being disabled, if irqs
- * had ever been enabled during this RCU critical section
- * (could leak a special flag and delay reporting the qs).
- */
- if ((oldmask & RCUTORTURE_RDR_RCU) &&
- (mask & RCUTORTURE_RDR_IRQ) &&
- !(mask & preempts))
- mask |= RCUTORTURE_RDR_RCU;
-
- /* Can't modify non-atomic bh in atomic context */
- tmp = nonatomic_bhs;
+ /* Can't modify BH in atomic context */
if (oldmask & preempts_irq)
- mask &= ~tmp;
+ mask &= ~bhs;
if ((oldmask | mask) & preempts_irq)
- mask |= oldmask & tmp;
+ mask |= oldmask & bhs;
}

return mask ?: RCUTORTURE_RDR_RCU;
diff --git a/localversion-rt b/localversion-rt
index 6e44e540b927b..9f7d0bdbffb18 100644
--- a/localversion-rt
+++ b/localversion-rt
@@ -1 +1 @@
--rt12
+-rt13

Next message: Segher Boessenkool: "Re: [PATCH] powerpc/booke: Avoid link stack corruption in several places"
Previous message: Philipp Zabel: "Re: [PATCH v2 1/4] ASoC: rockchip: add support for i2s-tdm controller"
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