Commit:     0d59a01bc461bbab4017ff449b8401151ef44cf6
Parent:     bcdddfb66cc998252d34758ce4109cedc0d24a5c
Author:     Adam Litke <[EMAIL PROTECTED]>
AuthorDate: Tue Jan 30 14:35:39 2007 -0800
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Tue Jan 30 16:01:35 2007 -0800

    [PATCH] Don't allow the stack to grow into hugetlb reserved regions
    When expanding the stack, we don't currently check if the VMA will cross
    into an area of the address space that is reserved for hugetlb pages.
    Subsequent faults on the expanded portion of such a VMA will confuse the
    low-level MMU code, resulting in an OOPS.  Check for this.
    Signed-off-by: Adam Litke <[EMAIL PROTECTED]>
    Cc: David Gibson <[EMAIL PROTECTED]>
    Cc: William Lee Irwin III <[EMAIL PROTECTED]>
    Cc: Hugh Dickins <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
 mm/mmap.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 9717337..cc3a208 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1477,6 +1477,7 @@ static int acct_stack_growth(struct vm_area_struct * vma, 
unsigned long size, un
        struct mm_struct *mm = vma->vm_mm;
        struct rlimit *rlim = current->signal->rlim;
+       unsigned long new_start;
        /* address space limit tests */
        if (!may_expand_vm(mm, grow))
@@ -1496,6 +1497,12 @@ static int acct_stack_growth(struct vm_area_struct * 
vma, unsigned long size, un
                        return -ENOMEM;
+       /* Check to ensure the stack will not grow into a hugetlb-only region */
+       new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
+                       vma->vm_end - size;
+       if (is_hugepage_only_range(vma->vm_mm, new_start, size))
+               return -EFAULT;
         * Overcommit..  This must be the final test, as it will
         * update security statistics.
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