Re: [PATCH] mm: mmap: Merge vma after call_mmap() if possible

[linmiaohe]

Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> On Tue, 14 Jul 2020 11:07:44 +0800 linmiaohe <linmiaohe@xxxxxxxxxx> wrote:
>
>> The vm_flags may be changed after call_mmap() because drivers may set 
>> some flags for their own purpose. As a result, we failed to merge the 
>> adjacent vma due to the different vm_flags as userspace can't pass in the same one.
>> Try to merge vma after call_mmap() to fix this issue.
>
>Which drivers do this?

I searched the code and I see many drivers change the vm_flags, such as aio_ring_mmap set
VM_DONTEXPAND and amdgpu_mmap , binder_mmap also change the vm_flags , and so on...

Thanks.