On 2/12/25 6:59 AM, Andrey Ryabinin wrote:
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?
Sure. We can certainly do that.
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.
AFAICS, vmalloc_to_page() doesn't seem to take any lock. Even if it takes another spinlock, it will still be under the vmalloc_map protection until lock_map_release() is called.
Cheers, Longman
