[linux-next:master 1977/2307] mm/hugetlb.c:3095:4: warning: array subscript -1 is below array bounds of 'struct list_head[1]'

[kernel test robot <lkp@intel.com>]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   be5c93fa674f0fc3c8f359c2143abce6bbb422e6
commit: f48ee682d55e3602fcc194cb93b8398f2546e53f [1977/2307] mm/hugetlb: free cross-zone bootmem gigantic pages after allocation
config: sparc-randconfig-r131-20260701 (https://download.01.org/0day-ci/archive/20260701/202607010945.6lDjBFTU-lkp@intel.com/config)
compiler: sparc64-linux-gcc (GCC) 8.5.0
sparse: v0.6.5-rc1
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260701/202607010945.6lDjBFTU-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/202607010945.6lDjBFTU-lkp@intel.com/

All warnings (new ones prefixed by >>):

   mm/hugetlb.c: In function 'alloc_bootmem_huge_page':
>> mm/hugetlb.c:3095:4: warning: array subscript -1 is below array bounds of 'struct list_head[1]' [-Warray-bounds]
       list_add(&m->list, &huge_boot_pages[nid_request]);
       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


vim +3095 mm/hugetlb.c

  3060	
  3061	static bool __init alloc_bootmem_huge_page(struct hstate *h, int nid)
  3062	{
  3063		unsigned long pfn;
  3064		unsigned int nid_request = nid;
  3065		struct huge_bootmem_page *m = arch_alloc_bootmem_huge_page(h, nid);
  3066	
  3067		if (!m)
  3068			return false;
  3069	
  3070		pfn = PHYS_PFN(__pa(m));
  3071		nid = early_pfn_to_nid(pfn);
  3072		/*
  3073		 * Use the beginning of the huge page to store the huge_bootmem_page
  3074		 * struct (until gather_bootmem puts them into the mem_map).
  3075		 *
  3076		 * Put them into a private list first because mem_map is not up yet.
  3077		 */
  3078		INIT_LIST_HEAD(&m->list);
  3079		m->hstate = h;
  3080		if (!hugetlb_early_cma(h)) {
  3081			m->cma = NULL;
  3082			m->flags = 0;
  3083		}
  3084	
  3085		/* CMA pages: zone-crossing is validated in hugetlb_cma_reserve(). */
  3086		if (!hugetlb_early_cma(h) &&
  3087		    pfn_range_intersects_zones(nid, pfn, pages_per_huge_page(h))) {
  3088			/*
  3089			 * If the allocated page is on a different node than requested
  3090			 * (e.g., on PowerPC LPARs), put it on the requested node's list,
  3091			 * because hugetlb_free_cross_zone_pages() only frees cross-zone
  3092			 * pages belonging to the requested node.
  3093			 */
  3094			if (WARN_ON_ONCE(nid_request != NUMA_NO_NODE && nid != nid_request))
> 3095				list_add(&m->list, &huge_boot_pages[nid_request]);
  3096			else
  3097				list_add(&m->list, &huge_boot_pages[nid]);
  3098		} else {
  3099			list_add_tail(&m->list, &huge_boot_pages[nid]);
  3100			m->flags |= HUGE_BOOTMEM_ZONES_VALID;
  3101			/*
  3102			 * Only initialize the head struct page in memmap_init_reserved_pages,
  3103			 * rest of the struct pages will be initialized by the HugeTLB
  3104			 * subsystem itself.
  3105			 * The head struct page is used to get folio information by the HugeTLB
  3106			 * subsystem like zone id and node id.
  3107			 */
  3108			memblock_reserved_mark_noinit(__pa((void *)m + PAGE_SIZE),
  3109					huge_page_size(h) - PAGE_SIZE);
  3110		}
  3111	
  3112		return true;
  3113	}
  3114	

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