__put_page(page);
}
+/**
+ * put_user_page() - release a gup-pinned page
+ * @page: pointer to page to be released
+ *
+ * Pages that were pinned via get_user_pages*() must be released via
+ * either put_user_page(), or one of the put_user_pages*() routines
+ * below. This is so that eventually, pages that are pinned via
+ * get_user_pages*() can be separately tracked and uniquely handled. In
+ * particular, interactions with RDMA and filesystems need special
+ * handling.
+ *
+ * put_user_page() and put_page() are not interchangeable, despite this early
+ * implementation that makes them look the same. put_user_page() calls must
+ * be perfectly matched up with get_user_page() calls.
+ */
+static inline void put_user_page(struct page *page)
+{
+ put_page(page);
+}
+
+void put_user_pages_dirty(struct page **pages, unsigned long npages);
+void put_user_pages_dirty_lock(struct page **pages, unsigned long npages);
+void put_user_pages(struct page **pages, unsigned long npages);
+
#if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP)
#define SECTION_IN_PAGE_FLAGS
#endif
long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
struct page **pages, unsigned int gup_flags);
-#if defined(CONFIG_FS_DAX) || defined(CONFIG_CMA)
-long get_user_pages_longterm(unsigned long start, unsigned long nr_pages,
- unsigned int gup_flags, struct page **pages,
- struct vm_area_struct **vmas);
-#else
-static inline long get_user_pages_longterm(unsigned long start,
- unsigned long nr_pages, unsigned int gup_flags,
- struct page **pages, struct vm_area_struct **vmas)
-{
- return get_user_pages(start, nr_pages, gup_flags, pages, vmas);
-}
-#endif /* CONFIG_FS_DAX */
-
-int get_user_pages_fast(unsigned long start, int nr_pages, int write,
- struct page **pages);
+int get_user_pages_fast(unsigned long start, int nr_pages,
+ unsigned int gup_flags, struct page **pages);
/* Container for pinned pfns / pages */
struct frame_vector {
#define FOLL_REMOTE 0x2000 /* we are working on non-current tsk/mm */
#define FOLL_COW 0x4000 /* internal GUP flag */
#define FOLL_ANON 0x8000 /* don't do file mappings */
+#define FOLL_LONGTERM 0x10000 /* mapping lifetime is indefinite: see below */
+
+/*
+ * NOTE on FOLL_LONGTERM:
+ *
+ * FOLL_LONGTERM indicates that the page will be held for an indefinite time
+ * period _often_ under userspace control. This is contrasted with
+ * iov_iter_get_pages() where usages which are transient.
+ *
+ * FIXME: For pages which are part of a filesystem, mappings are subject to the
+ * lifetime enforced by the filesystem and we need guarantees that longterm
+ * users like RDMA and V4L2 only establish mappings which coordinate usage with
+ * the filesystem. Ideas for this coordination include revoking the longterm
+ * pin, delaying writeback, bounce buffer page writeback, etc. As FS DAX was
+ * added after the problem with filesystems was found FS DAX VMAs are
+ * specifically failed. Filesystem pages are still subject to bugs and use of
+ * FOLL_LONGTERM should be avoided on those pages.
+ *
+ * FIXME: Also NOTE that FOLL_LONGTERM is not supported in every GUP call.
+ * Currently only get_user_pages() and get_user_pages_fast() support this flag
+ * and calls to get_user_pages_[un]locked are specifically not allowed. This
+ * is due to an incompatibility with the FS DAX check and
+ * FAULT_FLAG_ALLOW_RETRY
+ *
+ * In the CMA case: longterm pins in a CMA region would unnecessarily fragment
+ * that region. And so CMA attempts to migrate the page before pinning when
+ * FOLL_LONGTERM is specified.
+ */
static inline int vm_fault_to_errno(vm_fault_t vm_fault, int foll_flags)
{
int enable) { }
#endif
-#ifdef CONFIG_DEBUG_PAGEALLOC
extern bool _debug_pagealloc_enabled;
-extern void __kernel_map_pages(struct page *page, int numpages, int enable);
static inline bool debug_pagealloc_enabled(void)
{
- return _debug_pagealloc_enabled;
+ return IS_ENABLED(CONFIG_DEBUG_PAGEALLOC) && _debug_pagealloc_enabled;
}
+#if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_ARCH_HAS_SET_DIRECT_MAP)
+extern void __kernel_map_pages(struct page *page, int numpages, int enable);
+
static inline void
kernel_map_pages(struct page *page, int numpages, int enable)
{
- if (!debug_pagealloc_enabled())
- return;
-
__kernel_map_pages(page, numpages, enable);
}
#ifdef CONFIG_HIBERNATION
extern bool kernel_page_present(struct page *page);
#endif /* CONFIG_HIBERNATION */
-#else /* CONFIG_DEBUG_PAGEALLOC */
+#else /* CONFIG_DEBUG_PAGEALLOC || CONFIG_ARCH_HAS_SET_DIRECT_MAP */
static inline void
kernel_map_pages(struct page *page, int numpages, int enable) {}
#ifdef CONFIG_HIBERNATION
static inline bool kernel_page_present(struct page *page) { return true; }
#endif /* CONFIG_HIBERNATION */
-static inline bool debug_pagealloc_enabled(void)
-{
- return false;
-}
-#endif /* CONFIG_DEBUG_PAGEALLOC */
+#endif /* CONFIG_DEBUG_PAGEALLOC || CONFIG_ARCH_HAS_SET_DIRECT_MAP */
#ifdef __HAVE_ARCH_GATE_AREA
extern struct vm_area_struct *get_gate_vma(struct mm_struct *mm);