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

kernel test robot
2024-12-11T17:18:54Z

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

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