[PATCH v3] android: binder: use VM_ALLOC to get vm area

[PATCH v3] android: binder: use VM_ALLOC to get vm area

[Ganesh Mahendran]

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>
----
V3: update comments
V2: update comments
---
 drivers/android/binder_alloc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c
index 07b866a..5a426c8 100644
--- a/drivers/android/binder_alloc.c
+++ b/drivers/android/binder_alloc.c
@@ -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";
-- 
1.9.1

Re: [PATCH v3] android: binder: use VM_ALLOC to get vm area

[Greg KH]

On Wed, Jan 10, 2018 at 10:49:05AM +0800, Ganesh Mahendran wrote:
> 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>
> ----
> V3: update comments
> V2: update comments
> ---
>  drivers/android/binder_alloc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Martijn and Todd, any objections to this patch?

thanks,

greg k-h

Re: [PATCH v3] android: binder: use VM_ALLOC to get vm area

[Todd Kjos]

On Mon, Jan 22, 2018 at 7:54 AM, Greg KH <gregkh@linuxfoundation.org> wrote:
> On Wed, Jan 10, 2018 at 10:49:05AM +0800, Ganesh Mahendran wrote:
>> 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>
>> ----
>> V3: update comments
>> V2: update comments
>> ---
>>  drivers/android/binder_alloc.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> Martijn and Todd, any objections to this patch?

Looks fine to me. Arve, do you remember the rationale for using VM_IOREMAP?

>
> thanks,
>
> greg k-h

Re: [PATCH v3] android: binder: use VM_ALLOC to get vm area

[Arve Hjønnevåg]

On Mon, Jan 22, 2018 at 9:02 AM, Todd Kjos <tkjos@google.com> wrote:
> On Mon, Jan 22, 2018 at 7:54 AM, Greg KH <gregkh@linuxfoundation.org> wrote:
>> On Wed, Jan 10, 2018 at 10:49:05AM +0800, Ganesh Mahendran wrote:
>>> 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>
>>> ----
>>> V3: update comments
>>> V2: update comments
>>> ---
>>>  drivers/android/binder_alloc.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> Martijn and Todd, any objections to this patch?
>
> Looks fine to me. Arve, do you remember the rationale for using VM_IOREMAP?
>

I don't remember for sure, but I think it used alloc_vm_area at some
point, and that uses VM_IOREMAP.

-- 
Arve Hjønnevåg

Re: [PATCH v3] android: binder: use VM_ALLOC to get vm area

[Ganesh Mahendran]

Hi, Arve:

2018-01-23 2:55 GMT+08:00 Arve Hjønnevåg <arve@android.com>:
> On Mon, Jan 22, 2018 at 9:02 AM, Todd Kjos <tkjos@google.com> wrote:
>> On Mon, Jan 22, 2018 at 7:54 AM, Greg KH <gregkh@linuxfoundation.org> wrote:
>>> On Wed, Jan 10, 2018 at 10:49:05AM +0800, Ganesh Mahendran wrote:
>>>> 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>
>>>> ----
>>>> V3: update comments
>>>> V2: update comments
>>>> ---
>>>>  drivers/android/binder_alloc.c | 2 +-
>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> Martijn and Todd, any objections to this patch?
>>
>> Looks fine to me. Arve, do you remember the rationale for using VM_IOREMAP?
>>
>
> I don't remember for sure, but I think it used alloc_vm_area at some
> point, and that uses VM_IOREMAP.

Yes, in alloc_vm_area(), it uses VM_IOREMAP flag.

In binder, the ~1MB vm area is cut into binder_buffer which is not
even page aligned.
So for binder IPC, there is no need to align vm area(512KB now).
For 64 bit OS, the vm area is very big, but for 32 bit OS, default vm
area is only 240.
The vm area will soon be exhausted, then no app can be launched.

Thanks.

>
> --
> Arve Hjønnevåg

Re: [PATCH v3] android: binder: use VM_ALLOC to get vm area

[Ganesh Mahendran]

Hi, Todd:

2018-01-23 1:02 GMT+08:00 Todd Kjos <tkjos@google.com>:
> On Mon, Jan 22, 2018 at 7:54 AM, Greg KH <gregkh@linuxfoundation.org> wrote:
>> On Wed, Jan 10, 2018 at 10:49:05AM +0800, Ganesh Mahendran wrote:
>>> 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>
>>> ----
>>> V3: update comments
>>> V2: update comments
>>> ---
>>>  drivers/android/binder_alloc.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> Martijn and Todd, any objections to this patch?
>
> Looks fine to me. Arve, do you remember the rationale for using VM_IOREMAP?

Thanks for your review.

>
>>
>> thanks,
>>
>> greg k-h

Re: [PATCH v3] android: binder: use VM_ALLOC to get vm area

[Martijn Coenen]

On Mon, Jan 22, 2018 at 4:54 PM, Greg KH <gregkh@linuxfoundation.org> wrote:
> Martijn and Todd, any objections to this patch?

Looks good to me.

>
> thanks,
>
> greg k-h

Re: [PATCH v3] android: binder: use VM_ALLOC to get vm area

[Ganesh Mahendran]

Hi, Martijn

2018-01-24 22:33 GMT+08:00 Martijn Coenen <maco@android.com>:
> On Mon, Jan 22, 2018 at 4:54 PM, Greg KH <gregkh@linuxfoundation.org> wrote:
>> Martijn and Todd, any objections to this patch?
>
> Looks good to me.

Thanks for your review.

Should I cherry-pick this change to aosp kernel 3.10/3.18/4.4/4.9 now?

Thanks.

>
>>
>> thanks,
>>
>> greg k-h

Re: [PATCH v3] android: binder: use VM_ALLOC to get vm area

[Greg KH]

On Thu, Jan 25, 2018 at 10:09:53AM +0800, Ganesh Mahendran wrote:
> Hi, Martijn
> 
> 2018-01-24 22:33 GMT+08:00 Martijn Coenen <maco@android.com>:
> > On Mon, Jan 22, 2018 at 4:54 PM, Greg KH <gregkh@linuxfoundation.org> wrote:
> >> Martijn and Todd, any objections to this patch?
> >
> > Looks good to me.
> 
> Thanks for your review.
> 
> Should I cherry-pick this change to aosp kernel 3.10/3.18/4.4/4.9 now?

If you need it "right now", sure.  Otherwise if you can wait 2 weeks, it
will automatically show up in the 3.18/4.4/4.9/4.14 android-common
branches as part of the stable kernel updates.

It's your choice, but either way to get it into 3.10, you will need to
submit it to AOSP.

thanks,

greg k-h