Sebastian Ott and Gerald Schaefer reported random crashes on s390. It was bisected to my THP refcounting patchset.
The problem is that pmdp_invalidated() called with wrong virtual address. It got offset up by HPAGE_PMD_SIZE by loop over ptes. The solution is to introduce new variable to be used in loop and don't touch 'haddr'. Signed-off-by: Kirill A. Shutemov <[email protected]> Reported-by: Gerald Schaefer <[email protected]> Reported-by Sebastian Ott <[email protected]> --- mm/huge_memory.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 1c317b85ea7d..e10a4fee88d2 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2836,6 +2836,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, pgtable_t pgtable; pmd_t _pmd; bool young, write, dirty; + unsigned long addr; int i; VM_BUG_ON(haddr & ~HPAGE_PMD_MASK); @@ -2865,7 +2866,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, pgtable = pgtable_trans_huge_withdraw(mm, pmd); pmd_populate(mm, &_pmd, pgtable); - for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { + for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { pte_t entry, *pte; /* * Note that NUMA hinting access restrictions are not @@ -2886,9 +2887,9 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, } if (dirty) SetPageDirty(page + i); - pte = pte_offset_map(&_pmd, haddr); + pte = pte_offset_map(&_pmd, addr); BUG_ON(!pte_none(*pte)); - set_pte_at(mm, haddr, pte, entry); + set_pte_at(mm, addr, pte, entry); atomic_inc(&page[i]._mapcount); pte_unmap(pte); } @@ -2938,7 +2939,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, pmd_populate(mm, pmd, pgtable); if (freeze) { - for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { + for (i = 0; i < HPAGE_PMD_NR; i++) { page_remove_rmap(page + i, false); put_page(page + i); } -- 2.7.0
