| Message ID | 6831bf69f7c7699be83b31c9c56212b5fb07f873.1644207242.git-series.apopple@nvidia.com |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | Migrate device coherent pages on get_user_pages() | expand |
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,
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; - if (args->start < args->vma->vm_start || - args->start >= args->vma->vm_end) - return -EINVAL; - if (args->end <= args->vma->vm_start || args->end > args->vma->vm_end) - return -EINVAL; if (!args->src || !args->dst) return -EINVAL; - - memset(args->src, 0, sizeof(*args->src) * nr_pages); - args->cpages = 0; - args->npages = 0; - - migrate_vma_collect(args); + if (args->vma) { + if (is_vm_hugetlb_page(args->vma) || + (args->vma->vm_flags & VM_SPECIAL) || vma_is_dax(args->vma)) + return -EINVAL; + if (args->start < args->vma->vm_start || + args->start >= args->vma->vm_end) + return -EINVAL; + if (args->end <= args->vma->vm_start || args->end > args->vma->vm_end) + return -EINVAL; + + memset(args->src, 0, sizeof(*args->src) * nr_pages); + args->cpages = 0; + args->npages = 0; + + migrate_vma_collect(args); + } if (args->cpages) migrate_vma_unmap(args); @@ -2804,7 +2804,7 @@ void migrate_vma_pages(struct migrate_vma *migrate) continue; } - if (!page) { + if (!page && migrate->vma) { if (!(migrate->src[i] & MIGRATE_PFN_MIGRATE)) continue; if (!notified) {