mm/gup: Remove the macro overload API migration helpers from the get_user*() APIs

The pkeys changes brought about a truly hideous set of macros in:

  cde70140fed8 ("mm/gup: Overload get_user_pages() functions")

... which macros are (ab-)using the fact that __VA_ARGS__ can be used
to shift parameter positions in macro arguments without breaking the
build and so can be used to call separate C functions depending on
the number of arguments of the macro.

This allowed easy migration of these 3 GUP APIs, as both these variants
worked at the C level:

  old:
	ret = get_user_pages(current, current->mm, address, 1, 1, 0, &page, NULL);

  new:
	ret = get_user_pages(address, 1, 1, 0, &page, NULL);

... while we also generated a (functionally harmless but noticeable) build
time warning if the old API was used. As there are over 300 uses of these
APIs, this trick eased the migration of the API and avoided excessive
migration pain in linux-next.

Now, with its work done, get rid of all of that complication and ugliness:

    3 files changed, 16 insertions(+), 140 deletions(-)

... where the linecount of the migration hack was further inflated by the
fact that there are NOMMU variants of these GUP APIs as well.

Much of the conversion was done in linux-next over the past couple of months,
and Linus recently removed all remaining old API uses from the upstream tree
in the following upstrea commit:

  cb107161df3c ("Convert straggling drivers to new six-argument get_user_pages()")

There was one more old-API usage in mm/gup.c, in the CONFIG_HAVE_GENERIC_RCU_GUP
code path that ARM, ARM64 and PowerPC uses.

After this commit any old API usage will break the build.

[ Also fixed a PowerPC/HAVE_GENERIC_RCU_GUP warning reported by Stephen Rothwell. ]

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

include/linux/mm.h

@@ -1250,78 +1250,20 @@ long get_user_pages_remote(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);
-long get_user_pages6(unsigned long start, unsigned long nr_pages,
+long get_user_pages(unsigned long start, unsigned long nr_pages,
 			    int write, int force, struct page **pages,
 			    struct vm_area_struct **vmas);
-long get_user_pages_locked6(unsigned long start, unsigned long nr_pages,
+long get_user_pages_locked(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_unlocked5(unsigned long start, unsigned long nr_pages,
+long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
 		    int write, int force, struct page **pages);
 int get_user_pages_fast(unsigned long start, int nr_pages, int write,
 			struct page **pages);
 
-/* suppress warnings from use in EXPORT_SYMBOL() */
-#ifndef __DISABLE_GUP_DEPRECATED
-#define __gup_deprecated __deprecated
-#else
-#define __gup_deprecated
-#endif
-/*
- * These macros provide backward-compatibility with the old
- * get_user_pages() variants which took tsk/mm.  These
- * functions/macros provide both compile-time __deprecated so we
- * can catch old-style use and not break the build.  The actual
- * functions also have WARN_ON()s to let us know at runtime if
- * the get_user_pages() should have been the "remote" variant.
- *
- * These are hideous, but temporary.
- *
- * If you run into one of these __deprecated warnings, look
- * at how you are calling get_user_pages().  If you are calling
- * it with current/current->mm as the first two arguments,
- * simply remove those arguments.  The behavior will be the same
- * as it is now.  If you are calling it on another task, use
- * get_user_pages_remote() instead.
- *
- * Any questions?  Ask Dave Hansen <dave@sr71.net>
- */
-long
-__gup_deprecated
-get_user_pages8(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);
-#define GUP_MACRO(_1, _2, _3, _4, _5, _6, _7, _8, get_user_pages, ...)	\
-	get_user_pages
-#define get_user_pages(...) GUP_MACRO(__VA_ARGS__,	\
-		get_user_pages8, x,			\
-		get_user_pages6, x, x, x, x, x)(__VA_ARGS__)
-
-__gup_deprecated
-long get_user_pages_locked8(struct task_struct *tsk, struct mm_struct *mm,
-		unsigned long start, unsigned long nr_pages,
-		int write, int force, struct page **pages,
-		int *locked);
-#define GUPL_MACRO(_1, _2, _3, _4, _5, _6, _7, _8, get_user_pages_locked, ...)	\
-	get_user_pages_locked
-#define get_user_pages_locked(...) GUPL_MACRO(__VA_ARGS__,	\
-		get_user_pages_locked8,	x,			\
-		get_user_pages_locked6, x, x, x, x)(__VA_ARGS__)
-
-__gup_deprecated
-long get_user_pages_unlocked7(struct task_struct *tsk, struct mm_struct *mm,
-		unsigned long start, unsigned long nr_pages,
-		int write, int force, struct page **pages);
-#define GUPU_MACRO(_1, _2, _3, _4, _5, _6, _7, get_user_pages_unlocked, ...)	\
-	get_user_pages_unlocked
-#define get_user_pages_unlocked(...) GUPU_MACRO(__VA_ARGS__,	\
-		get_user_pages_unlocked7, x,			\
-		get_user_pages_unlocked5, x, x, x, x)(__VA_ARGS__)
-
 /* Container for pinned pfns / pages */
 struct frame_vector {
 	unsigned int nr_allocated;	/* Number of frames we have space for */

mm/gup.c

@@ -1,4 +1,3 @@
-#define __DISABLE_GUP_DEPRECATED 1
 #include <linux/kernel.h>
 #include <linux/errno.h>
 #include <linux/err.h>
@@ -839,7 +838,7 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
  *      if (locked)
  *          up_read(&mm->mmap_sem);
  */
-long get_user_pages_locked6(unsigned long start, unsigned long nr_pages,
+long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
 			   int write, int force, struct page **pages,
 			   int *locked)
 {
@@ -847,7 +846,7 @@ long get_user_pages_locked6(unsigned long start, unsigned long nr_pages,
 				       write, force, pages, NULL, locked, true,
 				       FOLL_TOUCH);
 }
-EXPORT_SYMBOL(get_user_pages_locked6);
+EXPORT_SYMBOL(get_user_pages_locked);
 
 /*
  * Same as get_user_pages_unlocked(...., FOLL_TOUCH) but it allows to
@@ -892,13 +891,13 @@ EXPORT_SYMBOL(__get_user_pages_unlocked);
  * or if "force" shall be set to 1 (get_user_pages_fast misses the
  * "force" parameter).
  */
-long get_user_pages_unlocked5(unsigned long start, unsigned long nr_pages,
+long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
 			     int write, int force, struct page **pages)
 {
 	return __get_user_pages_unlocked(current, current->mm, start, nr_pages,
 					 write, force, pages, FOLL_TOUCH);
 }
-EXPORT_SYMBOL(get_user_pages_unlocked5);
+EXPORT_SYMBOL(get_user_pages_unlocked);
 
 /*
  * get_user_pages_remote() - pin user pages in memory
@@ -972,7 +971,7 @@ EXPORT_SYMBOL(get_user_pages_remote);
  * and mm being operated on are the current task's.  We also
  * obviously don't pass FOLL_REMOTE in here.
  */
-long get_user_pages6(unsigned long start, unsigned long nr_pages,
+long get_user_pages(unsigned long start, unsigned long nr_pages,
 		int write, int force, struct page **pages,
 		struct vm_area_struct **vmas)
 {
@@ -980,7 +979,7 @@ long get_user_pages6(unsigned long start, unsigned long nr_pages,
 				       write, force, pages, vmas, NULL, false,
 				       FOLL_TOUCH);
 }
-EXPORT_SYMBOL(get_user_pages6);
+EXPORT_SYMBOL(get_user_pages);
 
 /**
  * populate_vma_page_range() -  populate a range of pages in the vma.
@@ -1491,7 +1490,6 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
 int get_user_pages_fast(unsigned long start, int nr_pages, int write,
 			struct page **pages)
 {
-	struct mm_struct *mm = current->mm;
 	int nr, ret;
 
 	start &= PAGE_MASK;
@@ -1503,8 +1501,7 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write,
 		start += nr << PAGE_SHIFT;
 		pages += nr;
 
-		ret = get_user_pages_unlocked(current, mm, start,
-					      nr_pages - nr, write, 0, pages);
+		ret = get_user_pages_unlocked(start, nr_pages - nr, write, 0, pages);
 
 		/* Have to be a bit careful with return values */
 		if (nr > 0) {
@@ -1519,38 +1516,3 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write,
 }
 
 #endif /* CONFIG_HAVE_GENERIC_RCU_GUP */
-
-long get_user_pages8(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)
-{
-	WARN_ONCE(tsk != current, "get_user_pages() called on remote task");
-	WARN_ONCE(mm != current->mm, "get_user_pages() called on remote mm");
-
-	return get_user_pages6(start, nr_pages, write, force, pages, vmas);
-}
-EXPORT_SYMBOL(get_user_pages8);
-
-long get_user_pages_locked8(struct task_struct *tsk, struct mm_struct *mm,
-			    unsigned long start, unsigned long nr_pages,
-			    int write, int force, struct page **pages, int *locked)
-{
-	WARN_ONCE(tsk != current, "get_user_pages_locked() called on remote task");
-	WARN_ONCE(mm != current->mm, "get_user_pages_locked() called on remote mm");
-
-	return get_user_pages_locked6(start, nr_pages, write, force, pages, locked);
-}
-EXPORT_SYMBOL(get_user_pages_locked8);
-
-long get_user_pages_unlocked7(struct task_struct *tsk, struct mm_struct *mm,
-				  unsigned long start, unsigned long nr_pages,
-				  int write, int force, struct page **pages)
-{
-	WARN_ONCE(tsk != current, "get_user_pages_unlocked() called on remote task");
-	WARN_ONCE(mm != current->mm, "get_user_pages_unlocked() called on remote mm");
-
-	return get_user_pages_unlocked5(start, nr_pages, write, force, pages);
-}
-EXPORT_SYMBOL(get_user_pages_unlocked7);
-

mm/nommu.c

@@ -15,8 +15,6 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
-#define __DISABLE_GUP_DEPRECATED
-
 #include <linux/export.h>
 #include <linux/mm.h>
 #include <linux/vmacache.h>
@@ -161,7 +159,7 @@ finish_or_fault:
  *   slab page or a secondary page from a compound page
  * - don't permit access to VMAs that don't support it, such as I/O mappings
  */
-long get_user_pages6(unsigned long start, unsigned long nr_pages,
+long get_user_pages(unsigned long start, unsigned long nr_pages,
 		    int write, int force, struct page **pages,
 		    struct vm_area_struct **vmas)
 {
@@ -175,15 +173,15 @@ long get_user_pages6(unsigned long start, unsigned long nr_pages,
 	return __get_user_pages(current, current->mm, start, nr_pages, flags,
 				pages, vmas, NULL);
 }
-EXPORT_SYMBOL(get_user_pages6);
+EXPORT_SYMBOL(get_user_pages);
 
-long get_user_pages_locked6(unsigned long start, unsigned long nr_pages,
+long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
 			    int write, int force, struct page **pages,
 			    int *locked)
 {
-	return get_user_pages6(start, nr_pages, write, force, pages, NULL);
+	return get_user_pages(start, nr_pages, write, force, pages, NULL);
 }
-EXPORT_SYMBOL(get_user_pages_locked6);
+EXPORT_SYMBOL(get_user_pages_locked);
 
 long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
 			       unsigned long start, unsigned long nr_pages,
@@ -199,13 +197,13 @@ long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
 }
 EXPORT_SYMBOL(__get_user_pages_unlocked);
 
-long get_user_pages_unlocked5(unsigned long start, unsigned long nr_pages,
+long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
 			     int write, int force, struct page **pages)
 {
 	return __get_user_pages_unlocked(current, current->mm, start, nr_pages,
 					 write, force, pages, 0);
 }
-EXPORT_SYMBOL(get_user_pages_unlocked5);
+EXPORT_SYMBOL(get_user_pages_unlocked);
 
 /**
  * follow_pfn - look up PFN at a user virtual address
@@ -1989,31 +1987,3 @@ static int __meminit init_admin_reserve(void)
 	return 0;
 }
 subsys_initcall(init_admin_reserve);
-
-long get_user_pages8(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)
-{
-	return get_user_pages6(start, nr_pages, write, force, pages, vmas);
-}
-EXPORT_SYMBOL(get_user_pages8);
-
-long get_user_pages_locked8(struct task_struct *tsk, struct mm_struct *mm,
-			    unsigned long start, unsigned long nr_pages,
-			    int write, int force, struct page **pages,
-			    int *locked)
-{
-	return get_user_pages_locked6(start, nr_pages, write,
-				      force, pages, locked);
-}
-EXPORT_SYMBOL(get_user_pages_locked8);
-
-long get_user_pages_unlocked7(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_unlocked5(start, nr_pages, write, force, pages);
-}
-EXPORT_SYMBOL(get_user_pages_unlocked7);
-