mm: gup: add __get_user_pages_unlocked to customize gup_flags
Some callers (like KVM) may want to set the gup_flags like FOLL_HWPOSION
to get a proper -EHWPOSION retval instead of -EFAULT to take a more
appropriate action if get_user_pages runs into a memory failure.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Peter Feiner <pfeiner@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/gup.c b/mm/gup.c
index 71a3773..dad5875 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -582,9 +582,9 @@
int write, int force,
struct page **pages,
struct vm_area_struct **vmas,
- int *locked, bool notify_drop)
+ int *locked, bool notify_drop,
+ unsigned int flags)
{
- int flags = FOLL_TOUCH;
long ret, pages_done;
bool lock_dropped;
@@ -698,11 +698,37 @@
int *locked)
{
return __get_user_pages_locked(tsk, mm, start, nr_pages, write, force,
- pages, NULL, locked, true);
+ pages, NULL, locked, true, FOLL_TOUCH);
}
EXPORT_SYMBOL(get_user_pages_locked);
/*
+ * Same as get_user_pages_unlocked(...., FOLL_TOUCH) but it allows to
+ * pass additional gup_flags as last parameter (like FOLL_HWPOISON).
+ *
+ * NOTE: here FOLL_TOUCH is not set implicitly and must be set by the
+ * caller if required (just like with __get_user_pages). "FOLL_GET",
+ * "FOLL_WRITE" and "FOLL_FORCE" are set implicitly as needed
+ * according to the parameters "pages", "write", "force"
+ * respectively.
+ */
+__always_inline long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
+ unsigned long start, unsigned long nr_pages,
+ int write, int force, struct page **pages,
+ unsigned int gup_flags)
+{
+ long ret;
+ int locked = 1;
+ down_read(&mm->mmap_sem);
+ ret = __get_user_pages_locked(tsk, mm, start, nr_pages, write, force,
+ pages, NULL, &locked, false, gup_flags);
+ if (locked)
+ up_read(&mm->mmap_sem);
+ return ret;
+}
+EXPORT_SYMBOL(__get_user_pages_unlocked);
+
+/*
* get_user_pages_unlocked() is suitable to replace the form:
*
* down_read(&mm->mmap_sem);
@@ -723,14 +749,8 @@
unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages)
{
- long ret;
- int locked = 1;
- down_read(&mm->mmap_sem);
- ret = __get_user_pages_locked(tsk, mm, start, nr_pages, write, force,
- pages, NULL, &locked, false);
- if (locked)
- up_read(&mm->mmap_sem);
- return ret;
+ return __get_user_pages_unlocked(tsk, mm, start, nr_pages, write,
+ force, pages, FOLL_TOUCH);
}
EXPORT_SYMBOL(get_user_pages_unlocked);
@@ -794,7 +814,7 @@
int force, struct page **pages, struct vm_area_struct **vmas)
{
return __get_user_pages_locked(tsk, mm, start, nr_pages, write, force,
- pages, vmas, NULL, false);
+ pages, vmas, NULL, false, FOLL_TOUCH);
}
EXPORT_SYMBOL(get_user_pages);