On 1/26/22 03:48, Liam Howlett wrote:
> * Vlastimil Babka <vbabka@xxxxxxx> [220120 06:58]:
>> On 12/1/21 15:30, Liam Howlett wrote:
>> > From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx>
>> >
>> > Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
>> > Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
>> > ---
>> > mm/mempolicy.c | 53 ++++++++++++++++++++++++++------------------------
>> > 1 file changed, 28 insertions(+), 25 deletions(-)
>> >
>> > diff --git a/mm/mempolicy.c b/mm/mempolicy.c
>> > index 10e9c87260ed..0e2d918f4f30 100644
>> > --- a/mm/mempolicy.c
>> > +++ b/mm/mempolicy.c
>> > @@ -377,9 +377,10 @@ void mpol_rebind_task(struct task_struct *tsk, const nodemask_t *new)
>> > void mpol_rebind_mm(struct mm_struct *mm, nodemask_t *new)
>> > {
>> > struct vm_area_struct *vma;
>> > + MA_STATE(mas, &mm->mm_mt, 0, 0);
>>
>> VMA_ITERATOR?
>
> Yes, I will make this change. Thanks.
>
>>
>> >
>> > mmap_write_lock(mm);
>> > - for (vma = mm->mmap; vma; vma = vma->vm_next)
>> > + mas_for_each(&mas, vma, ULONG_MAX)
>> > mpol_rebind_policy(vma->vm_policy, new);
>> > mmap_write_unlock(mm);
>> > }
>> > @@ -652,7 +653,7 @@ static unsigned long change_prot_numa(struct vm_area_struct *vma,
>> > static int queue_pages_test_walk(unsigned long start, unsigned long end,
>> > struct mm_walk *walk)
>> > {
>> > - struct vm_area_struct *vma = walk->vma;
>> > + struct vm_area_struct *next, *vma = walk->vma;
>> > struct queue_pages *qp = walk->private;
>> > unsigned long endvma = vma->vm_end;
>> > unsigned long flags = qp->flags;
>> > @@ -667,9 +668,10 @@ static int queue_pages_test_walk(unsigned long start, unsigned long end,
>> > /* hole at head side of range */
>> > return -EFAULT;
>> > }
>> > + next = find_vma(vma->vm_mm, vma->vm_end);
>> > if (!(flags & MPOL_MF_DISCONTIG_OK) &&
>> > ((vma->vm_end < qp->end) &&
>> > - (!vma->vm_next || vma->vm_end < vma->vm_next->vm_start)))
>> > + (!next || vma->vm_end < next->vm_start)))
>> > /* hole at middle or tail of range */
>> > return -EFAULT;
>> >
>> > @@ -783,28 +785,24 @@ static int vma_replace_policy(struct vm_area_struct *vma,
>> > static int mbind_range(struct mm_struct *mm, unsigned long start,
>> > unsigned long end, struct mempolicy *new_pol)
>> > {
>> > - struct vm_area_struct *next;
>> > + MA_STATE(mas, &mm->mm_mt, start - 1, start - 1);
>> > struct vm_area_struct *prev;
>> > struct vm_area_struct *vma;
>> > int err = 0;
>> > pgoff_t pgoff;
>> > - unsigned long vmstart;
>> > - unsigned long vmend;
>> > -
>> > - vma = find_vma(mm, start);
>> > - VM_BUG_ON(!vma);
>> >
>> > - prev = vma->vm_prev;
>> > - if (start > vma->vm_start)
>> > - prev = vma;
>> > + prev = mas_find_rev(&mas, 0);
>> > + if (prev && (start < prev->vm_end))
>> > + vma = prev;
>> > + else
>> > + vma = mas_next(&mas, end - 1);
>> >
>> > - for (; vma && vma->vm_start < end; prev = vma, vma = next) {
>> > - next = vma->vm_next;
>> > - vmstart = max(start, vma->vm_start);
>> > - vmend = min(end, vma->vm_end);
>> > + do {
>> > + unsigned long vmstart = max(start, vma->vm_start);
>> > + unsigned long vmend = min(end, vma->vm_end);
>>
>> What if vma is null? Shouldn't this rather be a "for (; vma; vma =
>> mas_next(...)"
>
> We have already found the vma above.
AFAICS if the range intersects no vmas, we might have found a 'prev', but
'vma' might be NULL after the "vma = mas_next(&mas, end - 1);"?
