From: Christoph Hellwig <hch@infradead.org>
To: Todd Kjos <tkjos@android.com>
Cc: tkjos@google.com, gregkh@linuxfoundation.org, arve@android.com,
devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org,
maco@google.com, joel@joelfernandes.org, kernel-team@android.com
Subject: Re: [PATCH v3 0/7] binder: eliminate use of vmalloc space for binder buffers
Date: Mon, 11 Feb 2019 08:57:08 -0800 [thread overview]
Message-ID: <20190211165708.GA25685@infradead.org> (raw)
In-Reply-To: <20190208183520.30886-1-tkjos@google.com>
On Fri, Feb 08, 2019 at 10:35:13AM -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.
Is there any good reason to actually map the user memory to kernel
space instead of just using copy_{to,from}_user?
next prev parent reply other threads:[~2019-02-11 16:57 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-08 18:35 [PATCH v3 0/7] binder: eliminate use of vmalloc space for binder buffers Todd Kjos
2019-02-08 18:35 ` [PATCH v3 1/7] binder: create userspace-to-binder-buffer copy function Todd Kjos
2019-02-14 19:45 ` Joel Fernandes
2019-02-14 20:42 ` Todd Kjos
2019-02-14 20:53 ` Joel Fernandes
2019-02-14 21:25 ` Joel Fernandes
2019-02-14 21:55 ` Todd Kjos
2019-02-14 22:07 ` Joel Fernandes
2019-02-08 18:35 ` [PATCH v3 2/7] binder: add functions to copy to/from binder buffers Todd Kjos
2019-02-08 18:35 ` [PATCH v3 3/7] binder: add function to copy binder object from buffer Todd Kjos
2019-02-08 18:35 ` [PATCH v3 4/7] binder: avoid kernel vm_area for buffer fixups Todd Kjos
2019-02-08 18:35 ` [PATCH v3 5/7] binder: remove kernel vm_area for buffer space Todd Kjos
2019-02-08 18:35 ` [PATCH v3 6/7] binder: remove user_buffer_offset Todd Kjos
2019-02-08 18:35 ` [PATCH v3 7/7] binder: use userspace pointer as base of buffer space Todd Kjos
2019-02-11 16:57 ` Christoph Hellwig [this message]
2019-02-11 17:08 ` [PATCH v3 0/7] binder: eliminate use of vmalloc space for binder buffers Todd Kjos
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