[PATCH 66 of 66] add debug checks for mapcount related invariants

Andrea Arcangeli
2010-11-03T15:33:54Z

From: Andrea Arcangeli <aarcange@redhat.com>

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: Andrea Arcangeli <aarcange@redhat.com>
---

diff --git a/mm/memory.c b/mm/memory.c
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -804,6 +804,7 @@ static inline int copy_pmd_range(struct
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_rang
do {
next = pmd_addr_end(addr, end);
if (pmd_trans_huge(*pmd)) {
- if (next-addr != HPAGE_PMD_SIZE)
+ if (next-addr != HPAGE_PMD_SIZE) {
+ VM_BUG_ON(!rwsem_is_locked(&tlb->mm->mmap_sem));
split_huge_page_pmd(vma->vm_mm, pmd);
- else if (zap_huge_pmd(tlb, vma, pmd)) {
+ } else if (zap_huge_pmd(tlb, vma, pmd)) {
(*zap_work)--;
continue;
}