On Tue, Feb 11, 2025 at 5:08 PM Waiman Long <longman@xxxxxxxxxx> wrote:
> diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> index 3fe77a360f1c..e1ee687966aa 100644
> --- a/mm/kasan/report.c
> +++ b/mm/kasan/report.c
> @@ -398,9 +398,20 @@ static void print_address_description(void *addr, u8 tag,
> pr_err("\n");
> }
>
> - if (is_vmalloc_addr(addr)) {
> - struct vm_struct *va = find_vm_area(addr);
> + if (!is_vmalloc_addr(addr))
> + goto print_page;
>
> + /*
> + * RT kernel cannot call find_vm_area() in atomic context.
> + * For !RT kernel, prevent spinlock_t inside raw_spinlock_t warning
> + * by raising wait-type to WAIT_SLEEP.
> + */
> + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) {
> + static DEFINE_WAIT_OVERRIDE_MAP(vmalloc_map, LD_WAIT_SLEEP);
> + struct vm_struct *va;
> +
> + lock_map_acquire_try(&vmalloc_map);
> + va = find_vm_area(addr);
Can we hide all this logic behind some function like
kasan_find_vm_area() which would return NULL for -rt?
> if (va) {
> pr_err("The buggy address belongs to the virtual mapping at\n"
> " [%px, %px) created by:\n"
> @@ -410,8 +421,13 @@ static void print_address_description(void *addr, u8 tag,
>
> page = vmalloc_to_page(addr);
Or does vmalloc_to_page() secretly take some lock somewhere so we
need to guard it with this 'vmalloc_map' too?
So my suggestion above wouldn't be enough, if that's the case.
> }
> + lock_map_release(&vmalloc_map);
> + } else {
> + pr_err("The buggy address %px belongs to a vmalloc virtual mapping\n",
> + addr);
> }
>
