Displaying 4 results from an estimated 4 matches for "percpu_ref_tryget_l".
2019 Aug 16
2
[PATCH 04/15] mm: remove the pgmap field from struct hmm_vma_walk
...OK without having a get_dev_pagemap() ?
> >
> > Noting that the collision-retry scheme doesn't protect anything here
> > as we can have a concurrent invalidation while doing the above deref.
>
> As long take_driver_page_table_lock() in Jerome's flow can replace
> percpu_ref_tryget_live() on the pagemap reference. It seems
> nouveau_dmem_convert_pfn() happens after:
>
> mutex_lock(&svmm->mutex);
> if (!nouveau_range_done(&range)) {
>
> ...so I would expect that to be functionally equivalent to validat...
2019 Aug 15
4
[PATCH 04/15] mm: remove the pgmap field from struct hmm_vma_walk
On Thu, Aug 15, 2019 at 04:33:06PM -0400, Jerome Glisse wrote:
> So nor HMM nor driver should dereference the struct page (i do not
> think any iommu driver would either),
Er, they do technically deref the struct page:
nouveau_dmem_convert_pfn(struct nouveau_drm *drm,
struct hmm_range *range)
struct page *page;
page = hmm_pfn_to_page(range, range->pfns[i]);
if
2019 Aug 15
0
[PATCH 04/15] mm: remove the pgmap field from struct hmm_vma_walk
...;pgmap'
>
> Is this OK without having a get_dev_pagemap() ?
>
> Noting that the collision-retry scheme doesn't protect anything here
> as we can have a concurrent invalidation while doing the above deref.
As long take_driver_page_table_lock() in Jerome's flow can replace
percpu_ref_tryget_live() on the pagemap reference. It seems
nouveau_dmem_convert_pfn() happens after:
mutex_lock(&svmm->mutex);
if (!nouveau_range_done(&range)) {
...so I would expect that to be functionally equivalent to validating
the reference count.
2019 Aug 16
0
[PATCH 04/15] mm: remove the pgmap field from struct hmm_vma_walk
...agemap() ?
> > >
> > > Noting that the collision-retry scheme doesn't protect anything here
> > > as we can have a concurrent invalidation while doing the above deref.
> >
> > As long take_driver_page_table_lock() in Jerome's flow can replace
> > percpu_ref_tryget_live() on the pagemap reference. It seems
> > nouveau_dmem_convert_pfn() happens after:
> >
> > mutex_lock(&svmm->mutex);
> > if (!nouveau_range_done(&range)) {
> >
> > ...so I would expect that to be funct...