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Commit e0897d75 authored by David Rientjes's avatar David Rientjes Committed by Linus Torvalds
Browse files

mm, thp: print useful information when mmap_sem is unlocked in zap_pmd_range 



Andrea asked for addr, end, vma->vm_start, and vma->vm_end to be emitted
when !rwsem_is_locked(&tlb->mm->mmap_sem).  Otherwise, debugging the
underlying issue is more difficult.

Suggested-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 436814e6

mm/memory.c

+9 −1
Original line number Diff line number Diff line
@@ -1225,7 +1225,15 @@ static inline unsigned long zap_pmd_range(struct mmu_gather *tlb, 
		next = pmd_addr_end(addr, end);

		if (pmd_trans_huge(*pmd)) {

			if (next - addr != HPAGE_PMD_SIZE) {

				VM_BUG_ON(!rwsem_is_locked(&tlb->mm->mmap_sem));

#ifdef CONFIG_DEBUG_VM

				if (!rwsem_is_locked(&tlb->mm->mmap_sem)) {

					pr_err("%s: mmap_sem is unlocked! addr=0x%lx end=0x%lx vma->vm_start=0x%lx vma->vm_end=0x%lx\n",

						__func__, addr, end,

						vma->vm_start,

						vma->vm_end);

					BUG();

				}

#endif

				split_huge_page_pmd(vma->vm_mm, pmd);

			} else if (zap_huge_pmd(tlb, vma, pmd, addr))

				goto next;