diff options
Diffstat (limited to 'mm/migrate_device.c')
| -rw-r--r-- | mm/migrate_device.c | 52 |
1 files changed, 52 insertions, 0 deletions
diff --git a/mm/migrate_device.c b/mm/migrate_device.c index 18bc6483f63a..7feeb447e3b9 100644 --- a/mm/migrate_device.c +++ b/mm/migrate_device.c @@ -686,6 +686,12 @@ void migrate_vma_pages(struct migrate_vma *migrate) } if (!page) { + /* + * The only time there is no vma is when called from + * migrate_device_coherent_page(). However this isn't + * called if the page could not be unmapped. + */ + VM_BUG_ON(!migrate->vma); if (!(migrate->src[i] & MIGRATE_PFN_MIGRATE)) continue; if (!notified) { @@ -794,3 +800,49 @@ void migrate_vma_finalize(struct migrate_vma *migrate) } } EXPORT_SYMBOL(migrate_vma_finalize); + +/* + * Migrate a device coherent page back to normal memory. The caller should have + * a reference on page which will be copied to the new page if migration is + * successful or dropped on failure. + */ +int migrate_device_coherent_page(struct page *page) +{ + unsigned long src_pfn, dst_pfn = 0; + struct migrate_vma args; + struct page *dpage; + + WARN_ON_ONCE(PageCompound(page)); + + lock_page(page); + src_pfn = migrate_pfn(page_to_pfn(page)) | MIGRATE_PFN_MIGRATE; + args.src = &src_pfn; + args.dst = &dst_pfn; + args.cpages = 1; + args.npages = 1; + args.vma = NULL; + + /* + * We don't have a VMA and don't need to walk the page tables to find + * the source page. So call migrate_vma_unmap() directly to unmap the + * page as migrate_vma_setup() will fail if args.vma == NULL. + */ + migrate_vma_unmap(&args); + if (!(src_pfn & MIGRATE_PFN_MIGRATE)) + return -EBUSY; + + dpage = alloc_page(GFP_USER | __GFP_NOWARN); + if (dpage) { + lock_page(dpage); + dst_pfn = migrate_pfn(page_to_pfn(dpage)); + } + + migrate_vma_pages(&args); + if (src_pfn & MIGRATE_PFN_MIGRATE) + copy_highpage(dpage, page); + migrate_vma_finalize(&args); + + if (src_pfn & MIGRATE_PFN_MIGRATE) + return 0; + return -EBUSY; +} |