mm: make do_mmap_pgoff return populate as a size in bytes, not as a bool

do_mmap_pgoff() rounds up the desired size to the next PAGE_SIZE
multiple, however there was no equivalent code in mm_populate(), which
caused issues.

This could be fixed by introduced the same rounding in mm_populate(),
however I think it's preferable to make do_mmap_pgoff() return populate
as a size rather than as a boolean, so we don't have to duplicate the
size rounding logic in mm_populate().

Signed-off-by: Michel Lespinasse <walken@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Tested-by: Andy Lutomirski <luto@amacapital.net>
Cc: Greg Ungerer <gregungerer@westnet.com.au>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/aio.c

@@ -101,9 +101,8 @@ static int aio_setup_ring(struct kioctx *ctx)
 	struct aio_ring *ring;
 	struct aio_ring_info *info = &ctx->ring_info;
 	unsigned nr_events = ctx->max_reqs;
-	unsigned long size;
+	unsigned long size, populate;
 	int nr_pages;
-	bool populate;
 
 	/* Compensate for the ring buffer's head/tail overlap entry */
 	nr_events += 2;	/* 1 is required, 2 for good luck */
@@ -150,7 +149,7 @@ static int aio_setup_ring(struct kioctx *ctx)
 		return -EAGAIN;
 	}
 	if (populate)
-		mm_populate(info->mmap_base, info->mmap_size);
+		mm_populate(info->mmap_base, populate);
 
 	ctx->user_id = info->mmap_base;
 

include/linux/mm.h

@@ -1475,7 +1475,7 @@ extern unsigned long mmap_region(struct file *file, unsigned long addr,
 	unsigned long len, vm_flags_t vm_flags, unsigned long pgoff);
 extern unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
 	unsigned long len, unsigned long prot, unsigned long flags,
-	unsigned long pgoff, bool *populate);
+	unsigned long pgoff, unsigned long *populate);
 extern int do_munmap(struct mm_struct *, unsigned long, size_t);
 
 #ifdef CONFIG_MMU

ipc/shm.c

@@ -971,7 +971,7 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr,
 	struct shm_file_data *sfd;
 	struct path path;
 	fmode_t f_mode;
-	bool populate = false;
+	unsigned long populate = 0;
 
 	err = -EINVAL;
 	if (shmid < 0)
@@ -1078,7 +1078,7 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr,
 invalid:
 	up_write(&current->mm->mmap_sem);
 	if (populate)
-		mm_populate(addr, size);
+		mm_populate(addr, populate);
 
 out_fput:
 	fput(file);

mm/mmap.c

@@ -1163,13 +1163,13 @@ static inline unsigned long round_hint_to_min(unsigned long hint)
 unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
 			unsigned long len, unsigned long prot,
 			unsigned long flags, unsigned long pgoff,
-			bool *populate)
+			unsigned long *populate)
 {
 	struct mm_struct * mm = current->mm;
 	struct inode *inode;
 	vm_flags_t vm_flags;
 
-	*populate = false;
+	*populate = 0;
 
 	/*
 	 * Does the application expect PROT_READ to imply PROT_EXEC?
@@ -1307,7 +1307,7 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
 
 	addr = mmap_region(file, addr, len, vm_flags, pgoff);
 	if (!IS_ERR_VALUE(addr) && (vm_flags & VM_POPULATE))
-		*populate = true;
+		*populate = len;
 	return addr;
 }
 

mm/nommu.c

@@ -1251,7 +1251,7 @@ unsigned long do_mmap_pgoff(struct file *file,
 			    unsigned long prot,
 			    unsigned long flags,
 			    unsigned long pgoff,
-			    bool *populate)
+			    unsigned long *populate)
 {
 	struct vm_area_struct *vma;
 	struct vm_region *region;
@@ -1261,7 +1261,7 @@ unsigned long do_mmap_pgoff(struct file *file,
 
 	kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff);
 
-	*populate = false;
+	*populate = 0;
 
 	/* decide whether we should attempt the mapping, and if so what sort of
 	 * mapping */

mm/util.c

@@ -355,7 +355,7 @@ unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
 {
 	unsigned long ret;
 	struct mm_struct *mm = current->mm;
-	bool populate;
+	unsigned long populate;
 
 	ret = security_mmap_file(file, prot, flag);
 	if (!ret) {
@@ -363,8 +363,8 @@ unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
 		ret = do_mmap_pgoff(file, addr, len, prot, flag, pgoff,
 				    &populate);
 		up_write(&mm->mmap_sem);
-		if (!IS_ERR_VALUE(ret) && populate)
-			mm_populate(ret, len);
+		if (populate)
+			mm_populate(ret, populate);
 	}
 	return ret;
 }