Hi Martin, kernel test robot noticed the following build warnings: url: https://github.com/intel-lab-lkp/linux/commits/Martin-Oliveira/kernfs-remove-page_mkwrite-from-vm_operations_struct/20240612-023130 base: 83a7eefedc9b56fe7bfeff13b6c7356688ffa670 patch link: https://lore.kernel.org/r/20240611182732.360317-2-martin.oliveira%40eideticom.com patch subject: [PATCH v2 1/4] kernfs: remove page_mkwrite() from vm_operations_struct config: i386-randconfig-141-20240612 (https://download.01.org/0day-ci/archive/20240613/202406130357.6NmgCbMP-lkp@xxxxxxxxx/config) compiler: gcc-12 (Ubuntu 12.3.0-9ubuntu2) 12.3.0 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@xxxxxxxxx> | Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> | Closes: https://lore.kernel.org/r/202406130357.6NmgCbMP-lkp@xxxxxxxxx/ smatch warnings: fs/kernfs/file.c:462 kernfs_fop_mmap() error: we previously assumed 'vma->vm_ops' could be null (see line 459) vim +462 fs/kernfs/file.c c637b8acbe079e Tejun Heo 2013-12-11 416 static int kernfs_fop_mmap(struct file *file, struct vm_area_struct *vma) 414985ae23c031 Tejun Heo 2013-11-28 417 { c525aaddc366df Tejun Heo 2013-12-11 418 struct kernfs_open_file *of = kernfs_of(file); 414985ae23c031 Tejun Heo 2013-11-28 419 const struct kernfs_ops *ops; 414985ae23c031 Tejun Heo 2013-11-28 420 int rc; 414985ae23c031 Tejun Heo 2013-11-28 421 9b2db6e1894577 Tejun Heo 2013-12-10 422 /* 9b2db6e1894577 Tejun Heo 2013-12-10 423 * mmap path and of->mutex are prone to triggering spurious lockdep 9b2db6e1894577 Tejun Heo 2013-12-10 424 * warnings and we don't want to add spurious locking dependency 9b2db6e1894577 Tejun Heo 2013-12-10 425 * between the two. Check whether mmap is actually implemented 9b2db6e1894577 Tejun Heo 2013-12-10 426 * without grabbing @of->mutex by testing HAS_MMAP flag. See the c810729fe6471a Ahelenia Ziemiańska 2023-12-21 427 * comment in kernfs_fop_open() for more details. 9b2db6e1894577 Tejun Heo 2013-12-10 428 */ df23fc39bce03b Tejun Heo 2013-12-11 429 if (!(of->kn->flags & KERNFS_HAS_MMAP)) 9b2db6e1894577 Tejun Heo 2013-12-10 430 return -ENODEV; 9b2db6e1894577 Tejun Heo 2013-12-10 431 414985ae23c031 Tejun Heo 2013-11-28 432 mutex_lock(&of->mutex); 414985ae23c031 Tejun Heo 2013-11-28 433 414985ae23c031 Tejun Heo 2013-11-28 434 rc = -ENODEV; c637b8acbe079e Tejun Heo 2013-12-11 435 if (!kernfs_get_active(of->kn)) 414985ae23c031 Tejun Heo 2013-11-28 436 goto out_unlock; 414985ae23c031 Tejun Heo 2013-11-28 437 324a56e16e44ba Tejun Heo 2013-12-11 438 ops = kernfs_ops(of->kn); 414985ae23c031 Tejun Heo 2013-11-28 439 rc = ops->mmap(of, vma); b44b2140265ddf Tejun Heo 2014-04-20 440 if (rc) b44b2140265ddf Tejun Heo 2014-04-20 441 goto out_put; 414985ae23c031 Tejun Heo 2013-11-28 442 414985ae23c031 Tejun Heo 2013-11-28 443 /* 414985ae23c031 Tejun Heo 2013-11-28 444 * PowerPC's pci_mmap of legacy_mem uses shmem_zero_setup() 414985ae23c031 Tejun Heo 2013-11-28 445 * to satisfy versions of X which crash if the mmap fails: that 414985ae23c031 Tejun Heo 2013-11-28 446 * substitutes a new vm_file, and we don't then want bin_vm_ops. 414985ae23c031 Tejun Heo 2013-11-28 447 */ 414985ae23c031 Tejun Heo 2013-11-28 448 if (vma->vm_file != file) 414985ae23c031 Tejun Heo 2013-11-28 449 goto out_put; 414985ae23c031 Tejun Heo 2013-11-28 450 414985ae23c031 Tejun Heo 2013-11-28 451 rc = -EINVAL; 414985ae23c031 Tejun Heo 2013-11-28 452 if (of->mmapped && of->vm_ops != vma->vm_ops) 414985ae23c031 Tejun Heo 2013-11-28 453 goto out_put; 414985ae23c031 Tejun Heo 2013-11-28 454 414985ae23c031 Tejun Heo 2013-11-28 455 /* 414985ae23c031 Tejun Heo 2013-11-28 456 * It is not possible to successfully wrap close. 414985ae23c031 Tejun Heo 2013-11-28 457 * So error if someone is trying to use close. 414985ae23c031 Tejun Heo 2013-11-28 458 */ 414985ae23c031 Tejun Heo 2013-11-28 @459 if (vma->vm_ops && vma->vm_ops->close) ^^^^^^^^^^^ If ->vm_ops is NULL 414985ae23c031 Tejun Heo 2013-11-28 460 goto out_put; 414985ae23c031 Tejun Heo 2013-11-28 461 927bb8d619fea4 Martin Oliveira 2024-06-11 @462 if (vma->vm_ops->page_mkwrite) ^^^^^^^^^^^^^^^^^^^^^^^^^ then we're in trouble 927bb8d619fea4 Martin Oliveira 2024-06-11 463 goto out_put; 927bb8d619fea4 Martin Oliveira 2024-06-11 464 414985ae23c031 Tejun Heo 2013-11-28 465 rc = 0; 05d8f255867e31 Neel Natu 2024-01-27 466 if (!of->mmapped) { a1d82aff5df760 Tejun Heo 2016-12-27 467 of->mmapped = true; bdb2fd7fc56e19 Tejun Heo 2022-08-27 468 of_on(of)->nr_mmapped++; 414985ae23c031 Tejun Heo 2013-11-28 469 of->vm_ops = vma->vm_ops; 05d8f255867e31 Neel Natu 2024-01-27 470 } 414985ae23c031 Tejun Heo 2013-11-28 471 vma->vm_ops = &kernfs_vm_ops; 414985ae23c031 Tejun Heo 2013-11-28 472 out_put: c637b8acbe079e Tejun Heo 2013-12-11 473 kernfs_put_active(of->kn); 414985ae23c031 Tejun Heo 2013-11-28 474 out_unlock: 414985ae23c031 Tejun Heo 2013-11-28 475 mutex_unlock(&of->mutex); 414985ae23c031 Tejun Heo 2013-11-28 476 414985ae23c031 Tejun Heo 2013-11-28 477 return rc; 414985ae23c031 Tejun Heo 2013-11-28 478 } -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests/wiki
