On Tue 19-12-17 20:29:56, Tetsuo Handa wrote:
> 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;
> ^~~
http://lkml.kernel.org/r/20171215125129.2948634-1-arnd@xxxxxxxx
--
Michal Hocko
SUSE Labs
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