[RFC/PATCH 2/5] mm: get_user_pages: use static inline
__get_user_pages() is already exported function, so get_user_pages()
can be easily inlined to the caller functions.
Signed-off-by: Marek Szyprowski
Signed-off-by: Kyungmin Park
---
include/linux/mm.h | 74 +---
mm/memory.c| 69
2 files changed, 70 insertions(+), 73 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 7acc9dc..9806e54 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1019,10 +1019,7 @@ long __get_user_pages(struct task_struct *tsk, struct
mm_struct *mm,
unsigned long start, unsigned long nr_pages,
unsigned int foll_flags, struct page **pages,
struct vm_area_struct **vmas, int *nonblocking);
-long get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
- unsigned long start, unsigned long nr_pages,
- int write, int force, struct page **pages,
- struct vm_area_struct **vmas);
+
int get_user_pages_fast(unsigned long start, int nr_pages, int write,
struct page **pages);
struct kvec;
@@ -1642,6 +1639,75 @@ typedef int (*pte_fn_t)(pte_t *pte, pgtable_t token,
unsigned long addr,
extern int apply_to_page_range(struct mm_struct *mm, unsigned long address,
unsigned long size, pte_fn_t fn, void *data);
+/*
+ * get_user_pages() - pin user pages in memory
+ * @tsk: the task_struct to use for page fault accounting, or
+ * NULL if faults are not to be recorded.
+ * @mm:mm_struct of target mm
+ * @start: starting user address
+ * @nr_pages: number of pages from start to pin
+ * @write: whether pages will be written to by the caller
+ * @force: whether to force write access even if user mapping is
+ * readonly. This will result in the page being COWed even
+ * in MAP_SHARED mappings. You do not want this.
+ * @pages: array that receives pointers to the pages pinned.
+ * Should be at least nr_pages long. Or NULL, if caller
+ * only intends to ensure the pages are faulted in.
+ * @vmas: array of pointers to vmas corresponding to each page.
+ * Or NULL if the caller does not require them.
+ *
+ * Returns number of pages pinned. This may be fewer than the number
+ * requested. If nr_pages is 0 or negative, returns 0. If no pages
+ * were pinned, returns -errno. Each page returned must be released
+ * with a put_page() call when it is finished with. vmas will only
+ * remain valid while mmap_sem is held.
+ *
+ * Must be called with mmap_sem held for read or write.
+ *
+ * get_user_pages walks a process's page tables and takes a reference to
+ * each struct page that each user address corresponds to at a given
+ * instant. That is, it takes the page that would be accessed if a user
+ * thread accesses the given user virtual address at that instant.
+ *
+ * This does not guarantee that the page exists in the user mappings when
+ * get_user_pages returns, and there may even be a completely different
+ * page there in some cases (eg. if mmapped pagecache has been invalidated
+ * and subsequently re faulted). However it does guarantee that the page
+ * won't be freed completely. And mostly callers simply care that the page
+ * contains data that was valid *at some point in time*. Typically, an IO
+ * or similar operation cannot guarantee anything stronger anyway because
+ * locks can't be held over the syscall boundary.
+ *
+ * If write=0, the page must not be written to. If the page is written to,
+ * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
+ * after the page is finished with, and before put_page is called.
+ *
+ * get_user_pages is typically used for fewer-copy IO operations, to get a
+ * handle on the memory by some means other than accesses via the user virtual
+ * addresses. The pages may be submitted for DMA to devices or accessed via
+ * their kernel linear mapping (via the kmap APIs). Care should be taken to
+ * use the correct cache flushing APIs.
+ *
+ * See also get_user_pages_fast, for performance critical applications.
+ */
+static inline long get_user_pages(struct task_struct *tsk, struct mm_struct
*mm,
+ unsigned long start, unsigned long nr_pages, int write,
+ int force, struct page **pages,
+ struct vm_area_struct **vmas)
+{
+ int flags = FOLL_TOUCH;
+
+ if (pages)
+ flags |= FOLL_GET;
+ if (write)
+ flags |= FOLL_WRITE;
+ if (force)
+ flags |= FOLL_FORCE;
+
+ return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
+ NULL);
+}
+
#ifdef CONFIG_PROC_FS
void vm_stat_account(struct mm_struct *, unsigned long, struct file *, long);
#else
diff --git
[RFC/PATCH 2/5] mm: get_user_pages: use static inline
__get_user_pages() is already exported function, so get_user_pages()
can be easily inlined to the caller functions.
Signed-off-by: Marek Szyprowski m.szyprow...@samsung.com
Signed-off-by: Kyungmin Park kyungmin.p...@samsung.com
---
include/linux/mm.h | 74 +---
mm/memory.c| 69
2 files changed, 70 insertions(+), 73 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 7acc9dc..9806e54 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1019,10 +1019,7 @@ long __get_user_pages(struct task_struct *tsk, struct
mm_struct *mm,
unsigned long start, unsigned long nr_pages,
unsigned int foll_flags, struct page **pages,
struct vm_area_struct **vmas, int *nonblocking);
-long get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
- unsigned long start, unsigned long nr_pages,
- int write, int force, struct page **pages,
- struct vm_area_struct **vmas);
+
int get_user_pages_fast(unsigned long start, int nr_pages, int write,
struct page **pages);
struct kvec;
@@ -1642,6 +1639,75 @@ typedef int (*pte_fn_t)(pte_t *pte, pgtable_t token,
unsigned long addr,
extern int apply_to_page_range(struct mm_struct *mm, unsigned long address,
unsigned long size, pte_fn_t fn, void *data);
+/*
+ * get_user_pages() - pin user pages in memory
+ * @tsk: the task_struct to use for page fault accounting, or
+ * NULL if faults are not to be recorded.
+ * @mm:mm_struct of target mm
+ * @start: starting user address
+ * @nr_pages: number of pages from start to pin
+ * @write: whether pages will be written to by the caller
+ * @force: whether to force write access even if user mapping is
+ * readonly. This will result in the page being COWed even
+ * in MAP_SHARED mappings. You do not want this.
+ * @pages: array that receives pointers to the pages pinned.
+ * Should be at least nr_pages long. Or NULL, if caller
+ * only intends to ensure the pages are faulted in.
+ * @vmas: array of pointers to vmas corresponding to each page.
+ * Or NULL if the caller does not require them.
+ *
+ * Returns number of pages pinned. This may be fewer than the number
+ * requested. If nr_pages is 0 or negative, returns 0. If no pages
+ * were pinned, returns -errno. Each page returned must be released
+ * with a put_page() call when it is finished with. vmas will only
+ * remain valid while mmap_sem is held.
+ *
+ * Must be called with mmap_sem held for read or write.
+ *
+ * get_user_pages walks a process's page tables and takes a reference to
+ * each struct page that each user address corresponds to at a given
+ * instant. That is, it takes the page that would be accessed if a user
+ * thread accesses the given user virtual address at that instant.
+ *
+ * This does not guarantee that the page exists in the user mappings when
+ * get_user_pages returns, and there may even be a completely different
+ * page there in some cases (eg. if mmapped pagecache has been invalidated
+ * and subsequently re faulted). However it does guarantee that the page
+ * won't be freed completely. And mostly callers simply care that the page
+ * contains data that was valid *at some point in time*. Typically, an IO
+ * or similar operation cannot guarantee anything stronger anyway because
+ * locks can't be held over the syscall boundary.
+ *
+ * If write=0, the page must not be written to. If the page is written to,
+ * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
+ * after the page is finished with, and before put_page is called.
+ *
+ * get_user_pages is typically used for fewer-copy IO operations, to get a
+ * handle on the memory by some means other than accesses via the user virtual
+ * addresses. The pages may be submitted for DMA to devices or accessed via
+ * their kernel linear mapping (via the kmap APIs). Care should be taken to
+ * use the correct cache flushing APIs.
+ *
+ * See also get_user_pages_fast, for performance critical applications.
+ */
+static inline long get_user_pages(struct task_struct *tsk, struct mm_struct
*mm,
+ unsigned long start, unsigned long nr_pages, int write,
+ int force, struct page **pages,
+ struct vm_area_struct **vmas)
+{
+ int flags = FOLL_TOUCH;
+
+ if (pages)
+ flags |= FOLL_GET;
+ if (write)
+ flags |= FOLL_WRITE;
+ if (force)
+ flags |= FOLL_FORCE;
+
+ return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
+ NULL);
+}
+
#ifdef CONFIG_PROC_FS
void vm_stat_account(struct mm_struct *, unsigned
