Re: [PATCH v3 1/3] kprobes: Add text_alloc() and text_free()

[Peter Zijlstra]

On Wed, Jul 15, 2020 at 01:32:27AM +0300, Jarkko Sakkinen wrote:
> +void *text_alloc(unsigned long size)
> +{
> +	void *p;
> +
> +	if (PAGE_ALIGN(size) > MODULES_LEN)
> +		return NULL;
> +
> +	p = __vmalloc_node_range(size, MODULE_ALIGN,
> +				    MODULES_VADDR + get_module_load_offset(),
> +				    MODULES_END, GFP_KERNEL,
> +				    PAGE_KERNEL, 0, NUMA_NO_NODE,
> +				    __builtin_return_address(0));
> +	if (p && (kasan_module_alloc(p, size) < 0)) {
> +		vfree(p);
> +		return NULL;
> +	}
> +
> +	return p;
> +}
> +
> +void text_free(void *region)
> +{
> +	/*
> +	 * This memory may be RO, and freeing RO memory in an interrupt is not
> +	 * supported by vmalloc.
> +	 */
> +	WARN_ON(in_interrupt());

I think that wants to be:

	lockdep_assert_irqs_enabled();

in_interrupt() isn't sufficient, interrupts must also not be disabled
when issuesing TLB invalidations.

> +
> +	vfree(region);
> +}