linux-kernel - Re: [PATCH v2 0/7] binder: eliminate use of vmalloc space for binder buffers

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Message-ID: <CAHRSSEzEW7AfhmrUbUJnL+DFB2sU2X7J8dnnkO6px7Z7BzpE=Q@mail.gmail.com>
Date:   Fri, 8 Feb 2019 08:44:18 -0800
From:   Todd Kjos <tkjos@...gle.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     Todd Kjos <tkjos@...roid.com>,
        Arve Hjønnevåg <arve@...roid.com>,
        "open list:ANDROID DRIVERS" <devel@...verdev.osuosl.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Martijn Coenen <maco@...gle.com>, joel@...lfernandes.org,
        Android Kernel Team <kernel-team@...roid.com>
Subject: Re: [PATCH v2 0/7] binder: eliminate use of vmalloc space for binder buffers

On Fri, Feb 8, 2019 at 3:26 AM Greg KH <gregkh@...uxfoundation.org> wrote:
>
> On Wed, Jan 30, 2019 at 02:46:48PM -0800, Todd Kjos wrote:
> > Binder buffers have always been mapped into kernel space
> > via map_kernel_range_noflush() to allow the binder driver
> > to modify the buffer before posting to userspace for
> > processing.
> >
> > In recent Android releases, the number of long-running
> > binder processes has increased to the point that for
> > 32-bit systems, there is a risk of running out of
> > vmalloc space.
> >
> > This patch set removes the persistent mapping of the
> > binder buffers into kernel space. Instead, the binder
> > driver creates temporary mappings with kmap() or
> > kmap_atomic() to copy to or from the buffer only when
> > necessary.
>
> This patch series blows up when I apply it to my char-misc-next branch:
>
> drivers/android/binder_alloc_selftest.c: In function ‘check_buffer_pages_allocated’:
> drivers/android/binder_alloc_selftest.c:108:44: error: ‘struct binder_buffer’ has no member named ‘data’
>   end = (void *)PAGE_ALIGN((uintptr_t)buffer->data + size);
>                                             ^~
> Did you forget to enable CONFIG_ANDROID_BINDER_IPC_SELFTEST when doing your
> builds?

I did forget. Thanks for catching this. I'll repost with the fix.

-Todd

>
> thanks,
>
> greg k-h