linux-kernel - mm/mprotect.c:450:23: sparse: sparse: cast to non-scalar

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Message-ID: <202501241212.q9AAshQc-lkp@intel.com>
Date: Fri, 24 Jan 2025 12:21:27 +0800
From: kernel test robot <lkp@...el.com>
To: Peter Xu <peterx@...hat.com>
Cc: oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Memory Management List <linux-mm@...ck.org>
Subject: mm/mprotect.c:450:23: sparse: sparse: cast to non-scalar

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   bc8198dc7ebc492ec3e9fa1617dcdfbe98e73b17
commit: cb0f01beb16669e91510fcdb2cea213931aee017 mm/mprotect: fix dax pud handlings
date:   5 months ago
config: alpha-randconfig-r112-20250124 (https://download.01.org/0day-ci/archive/20250124/202501241212.q9AAshQc-lkp@intel.com/config)
compiler: alpha-linux-gcc (GCC) 14.2.0
reproduce: (https://download.01.org/0day-ci/archive/20250124/202501241212.q9AAshQc-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@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202501241212.q9AAshQc-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
   mm/mprotect.c: note: in included file (through include/linux/mm.h, include/linux/pagewalk.h):
   include/linux/pgtable.h:317:16: sparse: sparse: cast to non-scalar
   include/linux/pgtable.h:317:16: sparse: sparse: cast from non-scalar
   include/linux/pgtable.h:317:16: sparse: sparse: cast to non-scalar
   include/linux/pgtable.h:317:16: sparse: sparse: cast from non-scalar
   mm/mprotect.c:291:9: sparse: sparse: context imbalance in 'change_pte_range' - unexpected unlock
>> mm/mprotect.c:450:23: sparse: sparse: cast to non-scalar
>> mm/mprotect.c:450:23: sparse: sparse: cast from non-scalar
   include/linux/pgtable.h:324:16: sparse: sparse: cast to non-scalar
   include/linux/pgtable.h:324:16: sparse: sparse: cast from non-scalar
   mm/mprotect.c:480:47: sparse: sparse: self-comparison always evaluates to false
   mm/mprotect.c:506:46: sparse: sparse: self-comparison always evaluates to false
   include/linux/pgtable.h:317:16: sparse: sparse: cast to non-scalar
   include/linux/pgtable.h:317:16: sparse: sparse: cast from non-scalar
   include/linux/pgtable.h:317:16: sparse: sparse: cast to non-scalar
   include/linux/pgtable.h:317:16: sparse: sparse: cast from non-scalar

vim +450 mm/mprotect.c

   428	
   429	static inline long change_pud_range(struct mmu_gather *tlb,
   430			struct vm_area_struct *vma, p4d_t *p4d, unsigned long addr,
   431			unsigned long end, pgprot_t newprot, unsigned long cp_flags)
   432	{
   433		struct mmu_notifier_range range;
   434		pud_t *pudp, pud;
   435		unsigned long next;
   436		long pages = 0, ret;
   437	
   438		range.start = 0;
   439	
   440		pudp = pud_offset(p4d, addr);
   441		do {
   442	again:
   443			next = pud_addr_end(addr, end);
   444			ret = change_prepare(vma, pudp, pmd, addr, cp_flags);
   445			if (ret) {
   446				pages = ret;
   447				break;
   448			}
   449	
 > 450			pud = READ_ONCE(*pudp);
   451			if (pud_none(pud))
   452				continue;
   453	
   454			if (!range.start) {
   455				mmu_notifier_range_init(&range,
   456							MMU_NOTIFY_PROTECTION_VMA, 0,
   457							vma->vm_mm, addr, end);
   458				mmu_notifier_invalidate_range_start(&range);
   459			}
   460	
   461			if (pud_leaf(pud)) {
   462				if ((next - addr != PUD_SIZE) ||
   463				    pgtable_split_needed(vma, cp_flags)) {
   464					__split_huge_pud(vma, pudp, addr);
   465					goto again;
   466				} else {
   467					ret = change_huge_pud(tlb, vma, pudp,
   468							      addr, newprot, cp_flags);
   469					if (ret == 0)
   470						goto again;
   471					/* huge pud was handled */
   472					if (ret == HPAGE_PUD_NR)
   473						pages += HPAGE_PUD_NR;
   474					continue;
   475				}
   476			}
   477	
   478			pages += change_pmd_range(tlb, vma, pudp, addr, next, newprot,
   479						  cp_flags);
   480		} while (pudp++, addr = next, addr != end);
   481	
   482		if (range.start)
   483			mmu_notifier_invalidate_range_end(&range);
   484	
   485		return pages;
   486	}
   487	

-- 
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https://github.com/intel/lkp-tests/wiki