Merge branch 'work.get_user_pages_fast' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull get_user_pages_fast updates from Al Viro:
 "A bit more get_user_pages work"

* 'work.get_user_pages_fast' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  kvm: switch get_user_page_nowait() to get_user_pages_unlocked()
  __get_user_pages_locked(): get rid of notify_drop argument
  get_user_pages_unlocked(): pass true to __get_user_pages_locked() notify_drop
  cris: switch to get_user_pages_fast()
  fold __get_user_pages_unlocked() into its sole remaining caller

arch/cris/arch-v32/drivers/cryptocop.c

@@ -2717,37 +2717,28 @@ static int cryptocop_ioctl_process(struct inode *inode, struct file *filp, unsig
 		}
 	}
 
-	/* Acquire the mm page semaphore. */
-	down_read(&current->mm->mmap_sem);
-
-	err = get_user_pages((unsigned long int)(oper.indata + prev_ix),
+	err = get_user_pages_fast((unsigned long)(oper.indata + prev_ix),
 			     noinpages,
-			     0,  /* read access only for in data */
-			     inpages,
-			     NULL);
+			     false,  /* read access only for in data */
+			     inpages);
 
 	if (err < 0) {
-		up_read(&current->mm->mmap_sem);
 		nooutpages = noinpages = 0;
 		DEBUG_API(printk("cryptocop_ioctl_process: get_user_pages indata\n"));
 		goto error_cleanup;
 	}
 	noinpages = err;
-	if (oper.do_cipher){
-		err = get_user_pages((unsigned long int)oper.cipher_outdata,
+	if (oper.do_cipher) {
+		err = get_user_pages_fast((unsigned long)oper.cipher_outdata,
 				     nooutpages,
-				     FOLL_WRITE, /* write access for out data */
-				     outpages,
-				     NULL);
-		up_read(&current->mm->mmap_sem);
+				     true, /* write access for out data */
+				     outpages);
 		if (err < 0) {
 			nooutpages = 0;
 			DEBUG_API(printk("cryptocop_ioctl_process: get_user_pages outdata\n"));
 			goto error_cleanup;
 		}
 		nooutpages = err;
-	} else {
-		up_read(&current->mm->mmap_sem);
 	}
 
 	/* Add 6 to nooutpages to make room for possibly inserted buffers for storing digest and

mm/gup.c

@@ -848,7 +848,7 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
 						unsigned long nr_pages,
 						struct page **pages,
 						struct vm_area_struct **vmas,
-						int *locked, bool notify_drop,
+						int *locked,
 						unsigned int flags)
 {
 	long ret, pages_done;
@@ -922,7 +922,7 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
 		pages++;
 		start += PAGE_SIZE;
 	}
-	if (notify_drop && lock_dropped && *locked) {
+	if (lock_dropped && *locked) {
 		/*
 		 * We must let the caller know we temporarily dropped the lock
 		 * and so the critical section protected by it was lost.
@@ -959,35 +959,11 @@ long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
 			   int *locked)
 {
 	return __get_user_pages_locked(current, current->mm, start, nr_pages,
-				       pages, NULL, locked, true,
+				       pages, NULL, locked,
 				       gup_flags | FOLL_TOUCH);
 }
 EXPORT_SYMBOL(get_user_pages_locked);
 
-/*
- * Same as get_user_pages_unlocked(...., FOLL_TOUCH) but it allows for
- * tsk, mm to be specified.
- *
- * 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"
- * is set implicitly if "pages" is non-NULL.
- */
-static __always_inline long __get_user_pages_unlocked(struct task_struct *tsk,
-		struct mm_struct *mm, unsigned long start,
-		unsigned long nr_pages, 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, pages, NULL,
-				      &locked, false, gup_flags);
-	if (locked)
-		up_read(&mm->mmap_sem);
-	return ret;
-}
-
 /*
  * get_user_pages_unlocked() is suitable to replace the form:
  *
@@ -1006,8 +982,16 @@ static __always_inline long __get_user_pages_unlocked(struct task_struct *tsk,
 long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
 			     struct page **pages, unsigned int gup_flags)
 {
-	return __get_user_pages_unlocked(current, current->mm, start, nr_pages,
-					 pages, gup_flags | FOLL_TOUCH);
+	struct mm_struct *mm = current->mm;
+	int locked = 1;
+	long ret;
+
+	down_read(&mm->mmap_sem);
+	ret = __get_user_pages_locked(current, mm, start, nr_pages, pages, NULL,
+				      &locked, gup_flags | FOLL_TOUCH);
+	if (locked)
+		up_read(&mm->mmap_sem);
+	return ret;
 }
 EXPORT_SYMBOL(get_user_pages_unlocked);
 
@@ -1073,7 +1057,7 @@ long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
 		struct vm_area_struct **vmas, int *locked)
 {
 	return __get_user_pages_locked(tsk, mm, start, nr_pages, pages, vmas,
-				       locked, true,
+				       locked,
 				       gup_flags | FOLL_TOUCH | FOLL_REMOTE);
 }
 EXPORT_SYMBOL(get_user_pages_remote);
@@ -1090,7 +1074,7 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
 		struct vm_area_struct **vmas)
 {
 	return __get_user_pages_locked(current, current->mm, start, nr_pages,
-				       pages, vmas, NULL, false,
+				       pages, vmas, NULL,
 				       gup_flags | FOLL_TOUCH);
 }
 EXPORT_SYMBOL(get_user_pages);

virt/kvm/kvm_main.c

@@ -1322,17 +1322,6 @@ unsigned long kvm_vcpu_gfn_to_hva_prot(struct kvm_vcpu *vcpu, gfn_t gfn, bool *w
 	return gfn_to_hva_memslot_prot(slot, gfn, writable);
 }
 
-static int get_user_page_nowait(unsigned long start, int write,
-		struct page **page)
-{
-	int flags = FOLL_NOWAIT | FOLL_HWPOISON;
-
-	if (write)
-		flags |= FOLL_WRITE;
-
-	return get_user_pages(start, 1, flags, page, NULL);
-}
-
 static inline int check_user_page_hwpoison(unsigned long addr)
 {
 	int rc, flags = FOLL_HWPOISON | FOLL_WRITE;
@@ -1381,7 +1370,8 @@ static bool hva_to_pfn_fast(unsigned long addr, bool atomic, bool *async,
 static int hva_to_pfn_slow(unsigned long addr, bool *async, bool write_fault,
 			   bool *writable, kvm_pfn_t *pfn)
 {
-	struct page *page[1];
+	unsigned int flags = FOLL_HWPOISON;
+	struct page *page;
 	int npages = 0;
 
 	might_sleep();
@@ -1389,35 +1379,26 @@ static int hva_to_pfn_slow(unsigned long addr, bool *async, bool write_fault,
 	if (writable)
 		*writable = write_fault;
 
-	if (async) {
-		down_read(&current->mm->mmap_sem);
-		npages = get_user_page_nowait(addr, write_fault, page);
-		up_read(&current->mm->mmap_sem);
-	} else {
-		unsigned int flags = FOLL_HWPOISON;
-
-		if (write_fault)
-			flags |= FOLL_WRITE;
+	if (write_fault)
+		flags |= FOLL_WRITE;
+	if (async)
+		flags |= FOLL_NOWAIT;
 
-		npages = get_user_pages_unlocked(addr, 1, page, flags);
-	}
+	npages = get_user_pages_unlocked(addr, 1, &page, flags);
 	if (npages != 1)
 		return npages;
 
 	/* map read fault as writable if possible */
 	if (unlikely(!write_fault) && writable) {
-		struct page *wpage[1];
+		struct page *wpage;
 
-		npages = __get_user_pages_fast(addr, 1, 1, wpage);
-		if (npages == 1) {
+		if (__get_user_pages_fast(addr, 1, 1, &wpage) == 1) {
 			*writable = true;
-			put_page(page[0]);
-			page[0] = wpage[0];
+			put_page(page);
+			page = wpage;
 		}
-
-		npages = 1;
 	}
-	*pfn = page_to_pfn(page[0]);
+	*pfn = page_to_pfn(page);
 	return npages;
 }