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

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 <aarcange@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 05b258e9

mm/memory.c

+4 −2
Original line number Diff line number Diff line
@@ -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) {

				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;

			}