Re: [akpm-mm:mm-unstable 61/88] mm/cma.c:811: warning: Function parameter or struct member 'gfp' not described in '__cma_alloc'

[Frank van der Linden <fvdl@google.com>]

On Thu, Jan 30, 2025 at 7:23 PM kernel test robot <lkp@intel.com> wrote:
>
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-unstable
> head:   495206a68b359eb6117d0860861578113bbb94e7
> commit: 77cbd63e91fa6c5f6157a30e61a380b6c47c1443 [61/88] mm, cma: support multiple contiguous ranges, if requested
> config: x86_64-buildonly-randconfig-001-20250131 (https://download.01.org/0day-ci/archive/20250131/202501311137.rMiQNfi3-lkp@intel.com/config)
> compiler: gcc-11 (Debian 11.3.0-12) 11.3.0
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250131/202501311137.rMiQNfi3-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/202501311137.rMiQNfi3-lkp@intel.com/
>
> All warnings (new ones prefixed by >>):
>
> >> mm/cma.c:811: warning: Function parameter or struct member 'gfp' not described in '__cma_alloc'
> >> mm/cma.c:811: warning: expecting prototype for cma_alloc(). Prototype was for __cma_alloc() instead
>
>
> vim +811 mm/cma.c
>
>    798
>    799  /**
>    800   * cma_alloc() - allocate pages from contiguous area
>    801   * @cma:   Contiguous memory region for which the allocation is performed.
>    802   * @count: Requested number of pages.
>    803   * @align: Requested alignment of pages (in PAGE_SIZE order).
>    804   * @no_warn: Avoid printing message about failed allocation
>    805   *
>    806   * This function allocates part of contiguous memory on specific
>    807   * contiguous memory area.
>    808   */
>    809  static struct page *__cma_alloc(struct cma *cma, unsigned long count,
>    810                         unsigned int align, gfp_t gfp)
>  > 811  {
>    812          struct page *page = NULL;
>    813          int ret = -ENOMEM, r;
>    814          unsigned long i;
>    815          const char *name = cma ? cma->name : NULL;
>    816
>    817          trace_cma_alloc_start(name, count, align);
>    818
>    819          if (!cma || !cma->count)
>    820                  return page;
>    821
>    822          pr_debug("%s(cma %p, name: %s, count %lu, align %d)\n", __func__,
>    823                  (void *)cma, cma->name, count, align);
>    824
>    825          if (!count)
>    826                  return page;
>    827
>    828          for (r = 0; r < cma->nranges; r++) {
>    829                  page = NULL;
>    830
>    831                  ret = cma_range_alloc(cma, &cma->ranges[r], count, align,
>    832                                         &page, gfp);
>    833                  if (ret != -EBUSY || page)
>    834                          break;
>    835          }
>    836
>    837          /*
>    838           * CMA can allocate multiple page blocks, which results in different
>    839           * blocks being marked with different tags. Reset the tags to ignore
>    840           * those page blocks.
>    841           */
>    842          if (page) {
>    843                  for (i = 0; i < count; i++)
>    844                          page_kasan_tag_reset(nth_page(page, i));
>    845          }
>    846
>    847          if (ret && !(gfp & __GFP_NOWARN)) {
>    848                  pr_err_ratelimited("%s: %s: alloc failed, req-size: %lu pages, ret: %d\n",
>    849                                     __func__, cma->name, count, ret);
>    850                  cma_debug_show_areas(cma);
>    851          }
>    852
>    853          pr_debug("%s(): returned %p\n", __func__, page);
>    854          trace_cma_alloc_finish(name, page ? page_to_pfn(page) : 0,
>    855                                 page, count, align, ret);
>    856          if (page) {
>    857                  count_vm_event(CMA_ALLOC_SUCCESS);
>    858                  cma_sysfs_account_success_pages(cma, count);
>    859          } else {
>    860                  count_vm_event(CMA_ALLOC_FAIL);
>    861                  cma_sysfs_account_fail_pages(cma, count);
>    862          }
>    863
>    864          return page;
>    865  }
>    866
>
> --
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki

I see, I left the description block at the top of __cma_alloc, so now
there's two of them - but it only describes cma_alloc correctly, since
that is what it's supposed to do. Will be fixed in v3.

- Frank