Commit 14d1a55c authored by Andrea Arcangeli's avatar Andrea Arcangeli Committed by Linus Torvalds

thp: add debug checks for mapcount related invariants

Add debug checks for invariants that if broken could lead to mapcount vs
page_mapcount debug checks to trigger later in split_huge_page.
Signed-off-by: default avatarAndrea Arcangeli <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 05b258e9
......@@ -804,6 +804,7 @@ static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src
next = pmd_addr_end(addr, end);
if (pmd_trans_huge(*src_pmd)) {
int err;
VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
err = copy_huge_pmd(dst_mm, src_mm,
dst_pmd, src_pmd, addr, vma);
if (err == -ENOMEM)
......@@ -1015,9 +1016,10 @@ static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
do {
next = pmd_addr_end(addr, end);
if (pmd_trans_huge(*pmd)) {
if (next-addr != HPAGE_PMD_SIZE)
if (next-addr != HPAGE_PMD_SIZE) {
split_huge_page_pmd(vma->vm_mm, pmd);
else if (zap_huge_pmd(tlb, vma, pmd)) {
} else if (zap_huge_pmd(tlb, vma, pmd)) {
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