Patch "android: binder: use VM_ALLOC to get vm area" has been added to the 4.15-stable tree

Patch "android: binder: use VM_ALLOC to get vm area" has been added to the 4.15-stable tree

[gregkh]

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 the 4.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     android-binder-use-vm_alloc-to-get-vm-area.patch
and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From aac6830ec1cb681544212838911cdc57f2638216 Mon Sep 17 00:00:00 2001
From: Ganesh Mahendran <opensource.ganesh@gmail.com>
Date: Wed, 10 Jan 2018 10:49:05 +0800
Subject: android: binder: use VM_ALLOC to get vm area

From: Ganesh Mahendran <opensource.ganesh@gmail.com>

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@gmail.com>
Acked-by: Martijn Coenen <maco@android.com>
Acked-by: Todd Kjos <tkjos@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 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";


Patches currently in stable-queue which might be from opensource.ganesh@gmail.com are

queue-4.15/android-binder-use-vm_alloc-to-get-vm-area.patch