On 2017/12/15 4:53, Yang Shi wrote:
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index ea4ff25..ecc2b68 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -1674,7 +1674,12 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
> spin_unlock(&khugepaged_mm_lock);
>
> mm = mm_slot->mm;
> - down_read(&mm->mmap_sem);
> + /*
> + * Not wait for semaphore to avoid long time waiting, just move
> + * to the next mm on the list.
> + */
> + if (unlikely(!down_read_trylock(&mm->mmap_sem)))
> + goto breakouterloop_mmap_sem;
> if (unlikely(khugepaged_test_exit(mm)))
> vma = NULL;
> else
>
You are jumping before initializing vma.
mm/khugepaged.c: In function ‘khugepaged’:
mm/khugepaged.c:1757:31: warning: ‘vma’ may be used uninitialized in this function [-Wmaybe-uninitialized]
if (khugepaged_test_exit(mm) || !vma) {
~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~
mm/khugepaged.c:1659:25: note: ‘vma’ was declared here
struct vm_area_struct *vma;
^~~
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