Avoid long term pinning for Coherent device type pages. This could interfere with their own device memory manager. If caller tries to get user device coherent pages with PIN_LONGTERM flag set, those pages will be migrated back to system memory.
Signed-off-by: Alex Sierra alex.sierra@amd.com --- mm/gup.c | 32 ++++++++++++++++++++++++++++++-- 1 file changed, 30 insertions(+), 2 deletions(-)
diff --git a/mm/gup.c b/mm/gup.c index 886d6148d3d0..1572eacf07f4 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -1689,17 +1689,37 @@ struct page *get_dump_page(unsigned long addr) #endif /* CONFIG_ELF_CORE */
#ifdef CONFIG_MIGRATION +static int migrate_device_page(unsigned long address, + struct page *page) +{ + struct vm_area_struct *vma = find_vma(current->mm, address); + struct vm_fault vmf = { + .vma = vma, + .address = address & PAGE_MASK, + .flags = FAULT_FLAG_USER, + .pgoff = linear_page_index(vma, address), + .gfp_mask = GFP_KERNEL, + .page = page, + }; + if (page->pgmap && page->pgmap->ops->migrate_to_ram) + return page->pgmap->ops->migrate_to_ram(&vmf); + + return -EBUSY; +} + /* * Check whether all pages are pinnable, if so return number of pages. If some * pages are not pinnable, migrate them, and unpin all pages. Return zero if * pages were migrated, or if some pages were not successfully isolated. * Return negative error if migration fails. */ -static long check_and_migrate_movable_pages(unsigned long nr_pages, +static long check_and_migrate_movable_pages(unsigned long start, + unsigned long nr_pages, struct page **pages, unsigned int gup_flags) { unsigned long i; + unsigned long page_index; unsigned long isolation_error_count = 0; bool drain_allow = true; LIST_HEAD(movable_page_list); @@ -1720,6 +1740,10 @@ static long check_and_migrate_movable_pages(unsigned long nr_pages, * If we get a movable page, since we are going to be pinning * these entries, try to move them out if possible. */ + if (is_device_page(head)) { + page_index = i; + goto unpin_pages; + } if (!is_pinnable_page(head)) { if (PageHuge(head)) { if (!isolate_huge_page(head, &movable_page_list)) @@ -1750,12 +1774,16 @@ static long check_and_migrate_movable_pages(unsigned long nr_pages, if (list_empty(&movable_page_list) && !isolation_error_count) return nr_pages;
+unpin_pages: if (gup_flags & FOLL_PIN) { unpin_user_pages(pages, nr_pages); } else { for (i = 0; i < nr_pages; i++) put_page(pages[i]); } + if (is_device_page(head)) + return migrate_device_page(start + page_index * PAGE_SIZE, head); + if (!list_empty(&movable_page_list)) { ret = migrate_pages(&movable_page_list, alloc_migration_target, NULL, (unsigned long)&mtc, MIGRATE_SYNC, @@ -1798,7 +1826,7 @@ static long __gup_longterm_locked(struct mm_struct *mm, NULL, gup_flags); if (rc <= 0) break; - rc = check_and_migrate_movable_pages(rc, pages, gup_flags); + rc = check_and_migrate_movable_pages(start, rc, pages, gup_flags); } while (!rc); memalloc_pin_restore(flags);