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    SubjectRe: [patch] NULL pointer check for vma->vm_mm
    On Fri, 1 Feb 2008 16:39:07 +0900 "Kenichi Okuyama" <> wrote:

    > Dear all,
    > I was looking at the ./mm/rmap.c .. I found that, in function
    > "page_referenced_one()",
    > struct mm_struct *mm = vma->vm_mm;
    > was being refererred without NULL check.
    > Though I do agree that this works for most of the cases, I thought it
    > is better to add
    > BUG_ON() for case of mm being NULL.
    > attached is the patch for this

    If we dereference NULL then the kernel will display basically the same
    information as would a BUG, and it takes the same action. So adding a
    BUG_ON here really doesn't gain us anything.

    Also, I think vma->vm_mm == 0 is not a valid state, so this just shouldn't
    happen - the code is OK to assume that a particular invariant is being

     \ /
      Last update: 2008-02-01 08:59    [W:0.019 / U:0.864 seconds]
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