From 453c719261c0b4030b2676124adb6e81c5fb6833 Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Thu, 20 Jan 2011 14:44:18 -0800 Subject: [PATCH] thp: keep highpte mapped until it is no longer needed Two users reported THP-related crashes on 32-bit x86 machines. Their oops reports indicated an invalid pte, and subsequent code inspection showed that the highpte is actually used after unmap. The fix is to unmap the pte only after all operations against it are finished. Signed-off-by: Johannes Weiner Reported-by: Ilya Dryomov Reported-by: werner Cc: Andrea Arcangeli Tested-by: Ilya Dryomov Tested-by: Steven Rostedt Signed-off-by: Linus Torvalds --- mm/huge_memory.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 004c9c2aac7..c4f634b3a48 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1837,9 +1837,9 @@ static void collapse_huge_page(struct mm_struct *mm, spin_lock(ptl); isolated = __collapse_huge_page_isolate(vma, address, pte); spin_unlock(ptl); - pte_unmap(pte); if (unlikely(!isolated)) { + pte_unmap(pte); spin_lock(&mm->page_table_lock); BUG_ON(!pmd_none(*pmd)); set_pmd_at(mm, address, pmd, _pmd); @@ -1856,6 +1856,7 @@ static void collapse_huge_page(struct mm_struct *mm, anon_vma_unlock(vma->anon_vma); __collapse_huge_page_copy(pte, new_page, vma, address, ptl); + pte_unmap(pte); __SetPageUptodate(new_page); pgtable = pmd_pgtable(_pmd); VM_BUG_ON(page_count(pgtable) != 1); -- 2.20.1