[PATCH 4.15 43/55] android: binder: use VM_ALLOC to get vm area

From: Greg Kroah-Hartman
Date: Fri Feb 02 2018 - 12:38:55 EST


4.15-stable review patch. If anyone has any objections, please let me know.

------------------

From: Ganesh Mahendran <opensource.ganesh@xxxxxxxxx>

commit aac6830ec1cb681544212838911cdc57f2638216 upstream.

VM_IOREMAP is used to access hardware through a mechanism called
I/O mapped memory. Android binder is a IPC machanism which will
not access I/O memory.

And VM_IOREMAP has alignment requiement which may not needed in
binder.
__get_vm_area_node()
{
...
if (flags & VM_IOREMAP)
align = 1ul << clamp_t(int, fls_long(size),
PAGE_SHIFT, IOREMAP_MAX_ORDER);
...
}

This patch will save some kernel vm area, especially for 32bit os.

In 32bit OS, kernel vm area is only 240MB. We may got below
error when launching a app:

<3>[ 4482.440053] binder_alloc: binder_alloc_mmap_handler: 15728 8ce67000-8cf65000 get_vm_area failed -12
<3>[ 4483.218817] binder_alloc: binder_alloc_mmap_handler: 15745 8ce67000-8cf65000 get_vm_area failed -12

Signed-off-by: Ganesh Mahendran <opensource.ganesh@xxxxxxxxx>
Acked-by: Martijn Coenen <maco@xxxxxxxxxxx>
Acked-by: Todd Kjos <tkjos@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/android/binder_alloc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/android/binder_alloc.c
+++ b/drivers/android/binder_alloc.c
@@ -666,7 +666,7 @@ int binder_alloc_mmap_handler(struct bin
goto err_already_mapped;
}

- area = get_vm_area(vma->vm_end - vma->vm_start, VM_IOREMAP);
+ area = get_vm_area(vma->vm_end - vma->vm_start, VM_ALLOC);
if (area == NULL) {
ret = -ENOMEM;
failure_string = "get_vm_area";