diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/vfio/vfio_iommu_type1.c | 26 |
1 files changed, 4 insertions, 22 deletions
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index 96fddc1dafc3..c9c10708a40f 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -294,31 +294,13 @@ static int vfio_lock_acct(struct vfio_dma *dma, long npage, bool async) * Some mappings aren't backed by a struct page, for example an mmap'd * MMIO range for our own or another device. These use a different * pfn conversion and shouldn't be tracked as locked pages. + * For compound pages, any driver that sets the reserved bit in head + * page needs to set the reserved bit in all subpages to be safe. */ static bool is_invalid_reserved_pfn(unsigned long pfn) { - if (pfn_valid(pfn)) { - bool reserved; - struct page *tail = pfn_to_page(pfn); - struct page *head = compound_head(tail); - reserved = !!(PageReserved(head)); - if (head != tail) { - /* - * "head" is not a dangling pointer - * (compound_head takes care of that) - * but the hugepage may have been split - * from under us (and we may not hold a - * reference count on the head page so it can - * be reused before we run PageReferenced), so - * we've to check PageTail before returning - * what we just read. - */ - smp_rmb(); - if (PageTail(tail)) - return reserved; - } - return PageReserved(tail); - } + if (pfn_valid(pfn)) + return PageReserved(pfn_to_page(pfn)); return true; } |