[davidhildenbrand:b4/fixes_core 13/48] mm/huge_memory.c:1506 do_huge_pmd_device_private() warn: inconsistent returns 'ptl'.

[davidhildenbrand:b4/fixes_core 13/48] mm/huge_memory.c:1506 do_huge_pmd_device_private() warn: inconsistent returns 'ptl'.

[kernel test robot]

Unfiltered warning: this smatch report is sent as-is and has not been
reviewed for false positives, so please treat it with due skepticism.

BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
TO: Josef Bacik <josef@toxicpanda.com>
CC: "David Hildenbrand (Arm)" <david@kernel.org>
CC: Zi Yan <ziy@nvidia.com>

tree:   https://github.com/davidhildenbrand/linux b4/fixes_core
head:   5a5358c39c5c72f054c891685f8479c06c5f42d0
commit: f3f48b7b516dd004913e7f6870651f4cb0bfeff8 [13/48] mm/huge_memory: fix livelock on device private folio
:::::: branch date: 21 hours ago
:::::: commit date: 21 hours ago
config: powerpc64-randconfig-r2201-20261029 (https://download.01.org/0day-ci/archive/20261029/202610290652.IGpu3Ps1-lkp@intel.com/config)
compiler: powerpc64-linux-gcc (GCC) 13.5.0
smatch: v0.5.0-9187-g5189e3fb

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>
| Reported-by: Dan Carpenter <error27@gmail.com>
| Closes: https://lore.kernel.org/r/202610290652.IGpu3Ps1-lkp@intel.com/

New smatch warnings:
mm/huge_memory.c:1506 do_huge_pmd_device_private() warn: inconsistent returns 'ptl'.

Old smatch warnings:
arch/powerpc/include/asm/book3s/64/pgtable.h:678 pte_swp_soft_dirty() warn: bitwise AND condition is false here

vim +/ptl +1506 mm/huge_memory.c

71e3aac0724ffe Andrea Arcangeli 2011-01-13  1470  
4964099163d052 Balbir Singh     2025-10-01  1471  vm_fault_t do_huge_pmd_device_private(struct vm_fault *vmf)
4964099163d052 Balbir Singh     2025-10-01  1472  {
4964099163d052 Balbir Singh     2025-10-01  1473  	struct vm_area_struct *vma = vmf->vma;
4964099163d052 Balbir Singh     2025-10-01  1474  	vm_fault_t ret = 0;
4964099163d052 Balbir Singh     2025-10-01  1475  	spinlock_t *ptl;
0ac881efe16468 Lorenzo Stoakes  2025-11-10  1476  	softleaf_t entry;
4964099163d052 Balbir Singh     2025-10-01  1477  	struct page *page;
4964099163d052 Balbir Singh     2025-10-01  1478  	struct folio *folio;
4964099163d052 Balbir Singh     2025-10-01  1479  
4964099163d052 Balbir Singh     2025-10-01  1480  	if (vmf->flags & FAULT_FLAG_VMA_LOCK) {
4964099163d052 Balbir Singh     2025-10-01  1481  		vma_end_read(vma);
4964099163d052 Balbir Singh     2025-10-01  1482  		return VM_FAULT_RETRY;
4964099163d052 Balbir Singh     2025-10-01  1483  	}
4964099163d052 Balbir Singh     2025-10-01  1484  
4964099163d052 Balbir Singh     2025-10-01  1485  	ptl = pmd_lock(vma->vm_mm, vmf->pmd);
4964099163d052 Balbir Singh     2025-10-01  1486  	if (unlikely(!pmd_same(*vmf->pmd, vmf->orig_pmd))) {
4964099163d052 Balbir Singh     2025-10-01  1487  		spin_unlock(ptl);
4964099163d052 Balbir Singh     2025-10-01  1488  		return 0;
4964099163d052 Balbir Singh     2025-10-01  1489  	}
4964099163d052 Balbir Singh     2025-10-01  1490  
0ac881efe16468 Lorenzo Stoakes  2025-11-10  1491  	entry = softleaf_from_pmd(vmf->orig_pmd);
0ac881efe16468 Lorenzo Stoakes  2025-11-10  1492  	page = softleaf_to_page(entry);
4964099163d052 Balbir Singh     2025-10-01  1493  	folio = page_folio(page);
4964099163d052 Balbir Singh     2025-10-01  1494  	vmf->page = page;
4964099163d052 Balbir Singh     2025-10-01  1495  	vmf->pte = NULL;
4964099163d052 Balbir Singh     2025-10-01  1496  	if (folio_trylock(folio)) {
4964099163d052 Balbir Singh     2025-10-01  1497  		folio_get(folio);
4964099163d052 Balbir Singh     2025-10-01  1498  		spin_unlock(ptl);
4964099163d052 Balbir Singh     2025-10-01  1499  		ret = page_pgmap(page)->ops->migrate_to_ram(vmf);
4964099163d052 Balbir Singh     2025-10-01  1500  		folio_unlock(folio);
4964099163d052 Balbir Singh     2025-10-01  1501  		folio_put(folio);
4964099163d052 Balbir Singh     2025-10-01  1502  	} else {
f3f48b7b516dd0 Josef Bacik      2026-10-13  1503  		softleaf_entry_wait_on_locked(entry, ptl);
4964099163d052 Balbir Singh     2025-10-01  1504  	}
4964099163d052 Balbir Singh     2025-10-01  1505  
4964099163d052 Balbir Singh     2025-10-01 @1506  	return ret;
4964099163d052 Balbir Singh     2025-10-01  1507  }
4964099163d052 Balbir Singh     2025-10-01  1508  

:::::: The code at line 1506 was first introduced by commit
:::::: 4964099163d0524a769d039ffa886bb4515136d0 mm/memory/fault: add THP fault handling for zone device private pages

:::::: TO: Balbir Singh <balbirs@nvidia.com>
:::::: CC: Andrew Morton <akpm@linux-foundation.org>

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