mm/mmap.c: use IS_ERR_VALUE to check return value of get_unmapped_area

get_unmapped_area() returns an address or -errno on failure.  Historically
we have checked for the failure by offset_in_page() which is correct but
quite hard to read.  Newer code started using IS_ERR_VALUE which is much
easier to read.  Convert remaining users of offset_in_page as well.

[mhocko@suse.com: rewrite changelog]
[mhocko@kernel.org: fix mremap.c and uprobes.c sites also]
Link: http://lkml.kernel.org/r/20191012102512.28051-1-pugaowei@gmail.comSigned-off-by: Gaowei Pu <pugaowei@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richardw.yang@linux.intel.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/events/uprobes.c

@@ -1457,7 +1457,7 @@ static int xol_add_vma(struct mm_struct *mm, struct xol_area *area)
 		/* Try to map as high as possible, this is only a hint. */
 		area->vaddr = get_unmapped_area(NULL, TASK_SIZE - PAGE_SIZE,
 						PAGE_SIZE, 0, 0);
-		if (area->vaddr & ~PAGE_MASK) {
+		if (IS_ERR_VALUE(area->vaddr)) {
 			ret = area->vaddr;
 			goto fail;
 		}

mm/mmap.c

@@ -1417,7 +1417,7 @@ unsigned long do_mmap(struct file *file, unsigned long addr,
 	 * that it represents a valid section of the address space.
 	 */
 	addr = get_unmapped_area(file, addr, len, pgoff, flags);
-	if (offset_in_page(addr))
+	if (IS_ERR_VALUE(addr))
 		return addr;
 
 	if (flags & MAP_FIXED_NOREPLACE) {
@@ -2981,15 +2981,16 @@ static int do_brk_flags(unsigned long addr, unsigned long len, unsigned long fla
 	struct rb_node **rb_link, *rb_parent;
 	pgoff_t pgoff = addr >> PAGE_SHIFT;
 	int error;
+	unsigned long mapped_addr;
 
 	/* Until we need other flags, refuse anything except VM_EXEC. */
 	if ((flags & (~VM_EXEC)) != 0)
 		return -EINVAL;
 	flags |= VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
 
-	error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
-	if (offset_in_page(error))
-		return error;
+	mapped_addr = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
+	if (IS_ERR_VALUE(mapped_addr))
+		return mapped_addr;
 
 	error = mlock_future_check(mm, mm->def_flags, len);
 	if (error)

mm/mremap.c

@@ -558,7 +558,7 @@ static unsigned long mremap_to(unsigned long addr, unsigned long old_len,
 	ret = get_unmapped_area(vma->vm_file, new_addr, new_len, vma->vm_pgoff +
 				((addr - vma->vm_start) >> PAGE_SHIFT),
 				map_flags);
-	if (offset_in_page(ret))
+	if (IS_ERR_VALUE(ret))
 		goto out1;
 
 	ret = move_vma(vma, addr, old_len, new_len, new_addr, locked, uf,
@@ -706,7 +706,7 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
 					vma->vm_pgoff +
 					((addr - vma->vm_start) >> PAGE_SHIFT),
 					map_flags);
-		if (offset_in_page(new_addr)) {
+		if (IS_ERR_VALUE(new_addr)) {
 			ret = new_addr;
 			goto out;
 		}