From a738e9bad6030d4fd33bfd7db3399a250b7e94d8 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 25 Aug 2022 18:41:27 +0200 Subject: mm/debug: Provide VM_WARN_ON_IRQS_ENABLED() Some places in the VM code expect interrupts disabled, which is a valid expectation on non-PREEMPT_RT kernels, but does not hold on RT kernels in some places because the RT spinlock substitution does not disable interrupts. To avoid sprinkling CONFIG_PREEMPT_RT conditionals into those places, provide VM_WARN_ON_IRQS_ENABLED() which is only enabled when VM_DEBUG=y and PREEMPT_RT=n. Signed-off-by: Thomas Gleixner Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra (Intel) Acked-by: Michal Hocko Link: https://lore.kernel.org/r/20220825164131.402717-5-bigeasy@linutronix.de --- lib/Kconfig.debug | 3 +++ 1 file changed, 3 insertions(+) (limited to 'lib') diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index bcbe60d6c80c..cdb4b27ef1a0 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -803,6 +803,9 @@ config ARCH_HAS_DEBUG_VM_PGTABLE An architecture should select this when it can successfully build and run DEBUG_VM_PGTABLE. +config DEBUG_VM_IRQSOFF + def_bool DEBUG_VM && !PREEMPT_RT + config DEBUG_VM bool "Debug VM" depends on DEBUG_KERNEL -- cgit v1.2.3 From 9458e0a78c45bc6537ce11eb9f03489eab92f9c2 Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Thu, 25 Aug 2022 18:41:30 +0200 Subject: flex_proportions: Disable preemption entering the write section. The seqcount fprop_global::sequence is not associated with a lock. The write section (fprop_new_period()) is invoked from a timer and since the softirq is preemptible on PREEMPT_RT it is possible to preempt the write section which is not desited. Disable preemption around the write section on PREEMPT_RT. Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20220825164131.402717-8-bigeasy@linutronix.de --- lib/flex_proportions.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'lib') diff --git a/lib/flex_proportions.c b/lib/flex_proportions.c index 05cccbcf1661..83332fefa6f4 100644 --- a/lib/flex_proportions.c +++ b/lib/flex_proportions.c @@ -70,6 +70,7 @@ bool fprop_new_period(struct fprop_global *p, int periods) */ if (events <= 1) return false; + preempt_disable_nested(); write_seqcount_begin(&p->sequence); if (periods < 64) events -= events >> periods; @@ -77,6 +78,7 @@ bool fprop_new_period(struct fprop_global *p, int periods) percpu_counter_add(&p->events, -events); p->period += periods; write_seqcount_end(&p->sequence); + preempt_enable_nested(); return true; } -- cgit v1.2.3