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Commit 0fd71a56 authored by Andrea Arcangeli's avatar Andrea Arcangeli Committed by Linus Torvalds
Browse files

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: default avatarAndrea Arcangeli <aarcange@redhat.com>
Reviewed-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Peter Feiner <pfeiner@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent f0818f47

include/linux/mm.h

+4 −0
Original line number Diff line number Diff line
@@ -1265,6 +1265,10 @@ long get_user_pages_locked(struct task_struct *tsk, struct mm_struct *mm, 
		    unsigned long start, unsigned long nr_pages,

		    int write, int force, struct page **pages,

		    int *locked);

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 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);

mm/gup.c

+32 −12
Original line number Diff line number Diff line
@@ -582,9 +582,9 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk, 
						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;
@@ -698,10 +698,36 @@ long get_user_pages_locked(struct task_struct *tsk, struct mm_struct *mm, 
			   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:

 *
@@ -723,14 +749,8 @@ 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)

{

	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 @@ long get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 
		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);

mm/nommu.c

+13 −3
Original line number Diff line number Diff line
@@ -224,9 +224,10 @@ long get_user_pages_locked(struct task_struct *tsk, struct mm_struct *mm, 
}

EXPORT_SYMBOL(get_user_pages_locked);



long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,

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)

			       int write, int force, struct page **pages,

			       unsigned int gup_flags)

{

	long ret;

	down_read(&mm->mmap_sem);
@@ -235,6 +236,15 @@ long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm, 
	up_read(&mm->mmap_sem);

	return ret;

}

EXPORT_SYMBOL(__get_user_pages_unlocked);



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)

{

	return __get_user_pages_unlocked(tsk, mm, start, nr_pages, write,

					 force, pages, 0);

}

EXPORT_SYMBOL(get_user_pages_unlocked);



/**