patch "android: binder: use VM_ALLOC to get vm area" added to char-misc-next

This is a note to let you know that I've just added the patch titled

android: binder: use VM_ALLOC to get vm area

to my char-misc git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
in the char-misc-next branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will also be merged in the next major kernel release during the merge window.

If you have any questions about this process, please let me know.

From: Ganesh Mahendran <[email protected]>
Date: Wed, 10 Jan 2018 10:49:05 +0800
Subject: android: binder: use VM_ALLOC to get vm area

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

----
V3: update comments
V2: update comments

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

index 07b866afee54..5a426c877dfb 100644
@@ -670,7 +670,7 @@ int binder_alloc_mmap_handler(struct binder_alloc *alloc,
 		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";

2.16.1