[patch v2] mm, thp: print useful information when mmap_sem is unlocked in zap_pmd_range
From: David Rientjes <rientjes@google.com>
Date: 2012-06-11 09:15:33
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lkml
Subsystem:
memory management, memory management - core, the rest · Maintainers:
Andrew Morton, David Hildenbrand, Linus Torvalds
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: Andrea Arcangeli <redacted> Signed-off-by: David Rientjes <rientjes@google.com> --- v2: print in hex rather than decimal mm/memory.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/mm/memory.c b/mm/memory.c
--- a/mm/memory.c
+++ b/mm/memory.c@@ -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; --
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