On 2/6/22 20:26, Alistair Popple wrote:
migrate_vma_setup() checks that a valid vma is passed so that the page tables can be walked to find the pfns associated with a given address range. However in some cases the pfns are already known, such as when migrating device coherent pages during pin_user_pages() meaning a valid vma isn't required.
Signed-off-by: Alistair Popple apopple@nvidia.com Acked-by: Felix Kuehling Felix.Kuehling@amd.com
Changes for v2:
- Added Felix's Acked-by
mm/migrate.c | 34 +++++++++++++++++----------------- 1 file changed, 17 insertions(+), 17 deletions(-)
Hi Alistair,
Another late-breaking review question, below. :)
diff --git a/mm/migrate.c b/mm/migrate.c index a9aed12..0d6570d 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -2602,24 +2602,24 @@ int migrate_vma_setup(struct migrate_vma *args)
args->start &= PAGE_MASK; args->end &= PAGE_MASK;
- if (!args->vma || is_vm_hugetlb_page(args->vma) ||
(args->vma->vm_flags & VM_SPECIAL) || vma_is_dax(args->vma))return -EINVAL;- if (nr_pages <= 0)
return -EINVAL;
Was the above check left out intentionally? If so, then it needs a commit description note. And maybe even a separate patch, because it changes the behavior.
If you do want to change the behavior:
* The kerneldoc comment above this function supports such a change: it requires returning 0 for the case of zero pages requested. So your change would bring the comments into alignment with the code.
* I don't think memset deals properly with a zero length input arg, so it's probably better to return 0, before that point.
thanks,