On 2024/12/6 18:46, Dan Carpenter wrote:
Hello Qi Zheng,
Commit e3aafd2d3551 ("mm: pgtable: reclaim empty PTE page in
madvise(MADV_DONTNEED)") from Dec 4, 2024 (linux-next), leads to the
following Smatch static checker warning:
mm/pt_reclaim.c:69 try_to_free_pte()
error: uninitialized symbol 'ptl'.
Thanks for reporting this! Will fix it like below:
diff --git a/mm/pt_reclaim.c b/mm/pt_reclaim.c
index 6540a3115dde8..7e9455a18aae7 100644
--- a/mm/pt_reclaim.c
+++ b/mm/pt_reclaim.c
@@ -36,7 +36,7 @@ void try_to_free_pte(struct mm_struct *mm, pmd_t *pmd,
unsigned long addr,
struct mmu_gather *tlb)
{
pmd_t pmdval;
- spinlock_t *pml, *ptl;
+ spinlock_t *pml, *ptl = NULL;
pte_t *start_pte, *pte;
int i;
mm/pt_reclaim.c
35 void try_to_free_pte(struct mm_struct *mm, pmd_t *pmd, unsigned long addr,
36 struct mmu_gather *tlb)
37 {
38 pmd_t pmdval;
39 spinlock_t *pml, *ptl;
40 pte_t *start_pte, *pte;
41 int i;
42
43 pml = pmd_lock(mm, pmd);
44 start_pte = pte_offset_map_rw_nolock(mm, pmd, addr, &pmdval, &ptl);
45 if (!start_pte)
46 goto out_ptl;
ptl is uninitialized on error.
47 if (ptl != pml)
48 spin_lock_nested(ptl, SINGLE_DEPTH_NESTING);
49
50 /* Check if it is empty PTE page */
51 for (i = 0, pte = start_pte; i < PTRS_PER_PTE; i++, pte++) {
52 if (!pte_none(ptep_get(pte)))
53 goto out_ptl;
54 }
55 pte_unmap(start_pte);
56
57 pmd_clear(pmd);
58
59 if (ptl != pml)
60 spin_unlock(ptl);
61 spin_unlock(pml);
62
63 free_pte(mm, addr, tlb, pmdval);
64
65 return;
66 out_ptl:
67 if (start_pte)
68 pte_unmap_unlock(start_pte, ptl);
--> 69 if (ptl != pml)
^^^
Uninitialized variable
70 spin_unlock(pml);
71 }
regards,
dan carpenter
