diff options
Diffstat (limited to 'mm/gup.c')
| -rw-r--r-- | mm/gup.c | 90 |
1 files changed, 79 insertions, 11 deletions
@@ -134,7 +134,7 @@ struct folio *try_grab_folio(struct page *page, int refs, unsigned int flags) * path. */ if (unlikely((flags & FOLL_LONGTERM) && - !is_pinnable_page(page))) + !is_longterm_pinnable_page(page))) return NULL; /* @@ -953,6 +953,25 @@ static int faultin_page(struct vm_area_struct *vma, } ret = handle_mm_fault(vma, address, fault_flags, NULL); + + if (ret & VM_FAULT_COMPLETED) { + /* + * With FAULT_FLAG_RETRY_NOWAIT we'll never release the + * mmap lock in the page fault handler. Sanity check this. + */ + WARN_ON_ONCE(fault_flags & FAULT_FLAG_RETRY_NOWAIT); + if (locked) + *locked = 0; + /* + * We should do the same as VM_FAULT_RETRY, but let's not + * return -EBUSY since that's not reflecting the reality of + * what has happened - we've just fully completed a page + * fault, with the mmap lock released. Use -EAGAIN to show + * that we want to take the mmap lock _again_. + */ + return -EAGAIN; + } + if (ret & VM_FAULT_ERROR) { int err = vm_fault_to_errno(ret, *flags); @@ -1179,6 +1198,7 @@ retry: case 0: goto retry; case -EBUSY: + case -EAGAIN: ret = 0; fallthrough; case -EFAULT: @@ -1305,6 +1325,18 @@ retry: return -EINTR; ret = handle_mm_fault(vma, address, fault_flags, NULL); + + if (ret & VM_FAULT_COMPLETED) { + /* + * NOTE: it's a pity that we need to retake the lock here + * to pair with the unlock() in the callers. Ideally we + * could tell the callers so they do not need to unlock. + */ + mmap_read_lock(mm); + *unlocked = true; + return 0; + } + if (ret & VM_FAULT_ERROR) { int err = vm_fault_to_errno(ret, 0); @@ -1370,7 +1402,7 @@ static __always_inline long __get_user_pages_locked(struct mm_struct *mm, /* VM_FAULT_RETRY couldn't trigger, bypass */ return ret; - /* VM_FAULT_RETRY cannot return errors */ + /* VM_FAULT_RETRY or VM_FAULT_COMPLETED cannot return errors */ if (!*locked) { BUG_ON(ret < 0); BUG_ON(ret >= nr_pages); @@ -1674,7 +1706,7 @@ static long __get_user_pages_locked(struct mm_struct *mm, unsigned long start, goto finish_or_fault; if (pages) { - pages[i] = virt_to_page(start); + pages[i] = virt_to_page((void *)start); if (pages[i]) get_page(pages[i]); } @@ -1883,7 +1915,7 @@ static long check_and_migrate_movable_pages(unsigned long nr_pages, unsigned long isolation_error_count = 0, i; struct folio *prev_folio = NULL; LIST_HEAD(movable_page_list); - bool drain_allow = true; + bool drain_allow = true, coherent_pages = false; int ret = 0; for (i = 0; i < nr_pages; i++) { @@ -1893,14 +1925,43 @@ static long check_and_migrate_movable_pages(unsigned long nr_pages, continue; prev_folio = folio; - if (folio_is_pinnable(folio)) + /* + * Device coherent pages are managed by a driver and should not + * be pinned indefinitely as it prevents the driver moving the + * page. So when trying to pin with FOLL_LONGTERM instead try + * to migrate the page out of device memory. + */ + if (folio_is_device_coherent(folio)) { + /* + * We always want a new GUP lookup with device coherent + * pages. + */ + pages[i] = 0; + coherent_pages = true; + + /* + * Migration will fail if the page is pinned, so convert + * the pin on the source page to a normal reference. + */ + if (gup_flags & FOLL_PIN) { + get_page(&folio->page); + unpin_user_page(&folio->page); + } + + ret = migrate_device_coherent_page(&folio->page); + if (ret) + goto unpin_pages; + continue; + } + if (folio_is_longterm_pinnable(folio)) + continue; /* * Try to move out any movable page before pinning the range. */ if (folio_test_hugetlb(folio)) { - if (!isolate_huge_page(&folio->page, + if (isolate_hugetlb(&folio->page, &movable_page_list)) isolation_error_count++; continue; @@ -1921,7 +1982,8 @@ static long check_and_migrate_movable_pages(unsigned long nr_pages, folio_nr_pages(folio)); } - if (!list_empty(&movable_page_list) || isolation_error_count) + if (!list_empty(&movable_page_list) || isolation_error_count || + coherent_pages) goto unpin_pages; /* @@ -1931,10 +1993,16 @@ static long check_and_migrate_movable_pages(unsigned long nr_pages, return nr_pages; unpin_pages: - if (gup_flags & FOLL_PIN) { - unpin_user_pages(pages, nr_pages); - } else { - for (i = 0; i < nr_pages; i++) + /* + * pages[i] might be NULL if any device coherent pages were found. + */ + for (i = 0; i < nr_pages; i++) { + if (!pages[i]) + continue; + + if (gup_flags & FOLL_PIN) + unpin_user_page(pages[i]); + else put_page(pages[i]); } |