On Thu 25-08-22 18:41:27, Sebastian Andrzej Siewior wrote:
> From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
>
> 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 <tglx@xxxxxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: linux-mm@xxxxxxxxx
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
> Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Thanks!
> ---
> include/linux/mmdebug.h | 6 ++++++
> lib/Kconfig.debug | 3 +++
> 2 files changed, 9 insertions(+)
>
> diff --git a/include/linux/mmdebug.h b/include/linux/mmdebug.h
> index 15ae78cd28536..b8728d11c9490 100644
> --- a/include/linux/mmdebug.h
> +++ b/include/linux/mmdebug.h
> @@ -94,6 +94,12 @@ void dump_mm(const struct mm_struct *mm);
> #define VM_WARN(cond, format...) BUILD_BUG_ON_INVALID(cond)
> #endif
>
> +#ifdef CONFIG_DEBUG_VM_IRQSOFF
> +#define VM_WARN_ON_IRQS_ENABLED() WARN_ON_ONCE(!irqs_disabled())
> +#else
> +#define VM_WARN_ON_IRQS_ENABLED() do { } while (0)
> +#endif
> +
> #ifdef CONFIG_DEBUG_VIRTUAL
> #define VIRTUAL_BUG_ON(cond) BUG_ON(cond)
> #else
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index 072e4b289c13e..c96fc6820544c 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
> --
> 2.37.2
--
Michal Hocko
SUSE Labs
