Re: [PATCH v3] mm/alloc_tag: Fix panic when CONFIG_KASAN enabled and CONFIG_KASAN_VMALLOC not enabled

Hao Ge
2024-12-12T02:23:32Z

Hi

Thanks for you report.

This version has been deprecated, and a new V4 version has been released.

On 12/12/24 01:18, kernel test robot wrote:
> Hi Hao,
>
> kernel test robot noticed the following build errors:
>
> [auto build test ERROR on akpm-mm/mm-everything]
>
> url: https://github.com/intel-lab-lkp/linux/commits/Hao-Ge/mm-alloc_tag-Fix-panic-when-CONFIG_KASAN-enabled-and-CONFIG_KASAN_VMALLOC-not-enabled/20241211-110206
> base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
> patch link: https://lore.kernel.org/r/20241211025755.56173-1-hao.ge%40linux.dev
> patch subject: [PATCH v3] mm/alloc_tag: Fix panic when CONFIG_KASAN enabled and CONFIG_KASAN_VMALLOC not enabled
> config: i386-buildonly-randconfig-005-20241211 (https://download.01.org/0day-ci/archive/20241212/202412120143.l3g6vx8b-lkp@intel.com/config)
> compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241212/202412120143.l3g6vx8b-lkp@intel.com/reproduce)
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202412120143.l3g6vx8b-lkp@intel.com/
>
> All errors (new ones prefixed by >>):
>
> lib/alloc_tag.c: In function 'vm_module_tags_populate':
>>> lib/alloc_tag.c:409:40: error: 'KASAN_SHADOW_SCALE_SHIFT' undeclared (first use in this function)
> 409 | (2 << KASAN_SHADOW_SCALE_SHIFT) - 1) >> KASAN_SHADOW_SCALE_SHIFT;
> | ^~~~~~~~~~~~~~~~~~~~~~~~
> lib/alloc_tag.c:409:40: note: each undeclared identifier is reported only once for each function it appears in
>
>
> vim +/KASAN_SHADOW_SCALE_SHIFT +409 lib/alloc_tag.c
>
> 402
> 403 static int vm_module_tags_populate(void)
> 404 {
> 405 unsigned long phys_end = ALIGN_DOWN(module_tags.start_addr, PAGE_SIZE) +
> 406 (vm_module_tags->nr_pages << PAGE_SHIFT);
> 407 unsigned long new_end = module_tags.start_addr + module_tags.size;
> 408 unsigned long phys_idx = (vm_module_tags->nr_pages +
> > 409 (2 << KASAN_SHADOW_SCALE_SHIFT) - 1) >> KASAN_SHADOW_SCALE_SHIFT;
> 410 unsigned long new_idx = 0;
> 411
> 412 if (phys_end < new_end) {
> 413 struct page **next_page = vm_module_tags->pages + vm_module_tags->nr_pages;
> 414 unsigned long more_pages;
> 415 unsigned long nr;
> 416
> 417 more_pages = ALIGN(new_end - phys_end, PAGE_SIZE) >> PAGE_SHIFT;
> 418 nr = alloc_pages_bulk_array_node(GFP_KERNEL | __GFP_NOWARN,
> 419 NUMA_NO_NODE, more_pages, next_page);
> 420 if (nr < more_pages ||
> 421 vmap_pages_range(phys_end, phys_end + (nr << PAGE_SHIFT), PAGE_KERNEL,
> 422 next_page, PAGE_SHIFT) < 0) {
> 423 /* Clean up and error out */
> 424 for (int i = 0; i < nr; i++)
> 425 __free_page(next_page[i]);
> 426 return -ENOMEM;
> 427 }
> 428
> 429 vm_module_tags->nr_pages += nr;
> 430
> 431 new_idx = (vm_module_tags->nr_pages +
> 432 (2 << KASAN_SHADOW_SCALE_SHIFT) - 1) >> KASAN_SHADOW_SCALE_SHIFT;
> 433
> 434 /*
> 435 * Kasan allocates 1 byte of shadow for every 8 bytes of data.
> 436 * When kasan_alloc_module_shadow allocates shadow memory,
> 437 * its unit of allocation is a page.
> 438 * Therefore, here we need to align to MODULE_ALIGN.
> 439 *
> 440 * For every KASAN_SHADOW_SCALE_SHIFT, a shadow page is allocated.
> 441 * So, we determine whether to allocate based on whether the
> 442 * number of pages falls within the scope of the same KASAN_SHADOW_SCALE_SHIFT.
> 443 */
> 444 if (phys_idx != new_idx)
> 445 kasan_alloc_module_shadow((void *)round_up(phys_end, MODULE_ALIGN),
> 446 (new_idx - phys_idx) * MODULE_ALIGN,
> 447 GFP_KERNEL);
> 448 }
> 449
> 450 /*
> 451 * Mark the pages as accessible, now that they are mapped.
> 452 * With hardware tag-based KASAN, marking is skipped for
> 453 * non-VM_ALLOC mappings, see __kasan_unpoison_vmalloc().
> 454 */
> 455 kasan_unpoison_vmalloc((void *)module_tags.start_addr,
> 456 new_end - module_tags.start_addr,
> 457 KASAN_VMALLOC_PROT_NORMAL);
> 458
> 459 return 0;
> 460 }
> 461
>