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

Greg KH
2018-01-22T15:54:30Z

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