On Wed 24-07-13 11:48:19, Libin wrote: > find_vma may return NULL, thus check the return > value to avoid NULL pointer dereference. Please add a note that the check matters only because khugepaged_alloc_page drops mmap_sem. > Signed-off-by: Libin <huawei.libin@xxxxxxxxxx> Other than that Reviewed-by: Michal Hocko <mhocko@xxxxxxx> + I guess this is worth backporting to the stable trees. This goes back to when khugepaged was introduced AFAICS. > --- > mm/huge_memory.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 243e710..d4423f4 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -2294,6 +2294,8 @@ static void collapse_huge_page(struct mm_struct *mm, > goto out; > > vma = find_vma(mm, address); > + if (!vma) > + goto out; > hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; > hend = vma->vm_end & HPAGE_PMD_MASK; > if (address < hstart || address + HPAGE_PMD_SIZE > hend) > -- > 1.8.2.1 > > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@xxxxxxxxx. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a> -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>