From: Mel Gorman Date: Thu, 12 Feb 2015 22:58:41 +0000 (-0800) Subject: mm: numa: add paranoid check around pte_protnone_numa X-Git-Tag: v4.14-rc1~5954^2~95 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=c0e7cad9f2390087b53e26e7b98958d8793ee02d;p=platform%2Fkernel%2Flinux-rpi.git mm: numa: add paranoid check around pte_protnone_numa pte_protnone_numa is only safe to use after VMA checks for PROT_NONE are complete. Treating a real PROT_NONE PTE as a NUMA hinting fault is going to result in strangeness so add a check for it. BUG_ON looks like overkill but if this is hit then it's a serious bug that could result in corruption so do not even try recovering. It would have been more comprehensive to check VMA flags in pte_protnone_numa but it would have made the API ugly just for a debugging check. Signed-off-by: Mel Gorman Cc: Aneesh Kumar K.V Cc: Benjamin Herrenschmidt Cc: Dave Jones Cc: Hugh Dickins Cc: Ingo Molnar Cc: Kirill Shutemov Cc: Linus Torvalds Cc: Paul Mackerras Cc: Rik van Riel Cc: Sasha Levin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 8e791a3..8e07342 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1262,6 +1262,9 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, bool migrated = false; int flags = 0; + /* A PROT_NONE fault should not end up here */ + BUG_ON(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))); + ptl = pmd_lock(mm, pmdp); if (unlikely(!pmd_same(pmd, *pmdp))) goto out_unlock; diff --git a/mm/memory.c b/mm/memory.c index bf244f5..f7886ab 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3013,6 +3013,9 @@ static int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, bool migrated = false; int flags = 0; + /* A PROT_NONE fault should not end up here */ + BUG_ON(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))); + /* * The "pte" at this point cannot be used safely without * validation through pte_unmap_same(). It's of NUMA type but