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[POWERPC] Fix bogus BUG_ON() in in hugetlb_get_unmapped_area()

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The powerpc specific version of hugetlb_get_unmapped_area() makes some
unwarranted assumptions about what checks have been made to its
parameters by its callers.  This will lead to a BUG_ON() if a 32-bit
process attempts to make a hugepage mapping which extends above
TASK_SIZE (4GB).

I'm not sure if these assumptions came about because they were valid
with earlier versions of the get_unmapped_area() path, or if it was
always broken.  Nonetheless this patch fixes the logic, and removes
the crash.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This commit is contained in:
David Gibson 2006-12-22 09:23:03 +11:00 committed by Paul Mackerras
parent efa06708fe
commit 6aa3e1e944
1 changed files with 4 additions and 4 deletions
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8
arch/powerpc/mm/hugetlbpage.c
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@ -744,7 +744,8 @@ static int htlb_check_hinted_area(unsigned long addr, unsigned long len)
struct vm_area_struct *vma;
vma = find_vma(current->mm, addr);
if (!vma || ((addr + len) <= vma->vm_start))
if (TASK_SIZE - len >= addr &&
(!vma || ((addr + len) <= vma->vm_start)))
return 0;
return -ENOMEM;
@ -815,6 +816,8 @@ unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
return -EINVAL;
if (len & ~HPAGE_MASK)
return -EINVAL;
if (len > TASK_SIZE)
return -ENOMEM;
if (!cpu_has_feature(CPU_FTR_16M_PAGE))
return -EINVAL;
@ -823,9 +826,6 @@ unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
BUG_ON((addr + len) < addr);
if (test_thread_flag(TIF_32BIT)) {
/* Paranoia, caller should have dealt with this */
BUG_ON((addr + len) > 0x100000000UL);
curareas = current->mm->context.low_htlb_areas;
/* First see if we can use the hint address */