Re: [PATCH] ARM:mm: fix kmap_atomic_to_page

From	Arnd Bergmann <arnd@arndb.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH] ARM:mm: fix kmap_atomic_to_page
Date	2015-10-12 11:30 +0200
Message-ID	<qiHAE-38y-37@gated-at.bofh.it> (permalink)
References	<qgyBr-4Iz-17@gated-at.bofh.it> <qgSTw-gt-5@gated-at.bofh.it> <qiE01-6lf-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Monday 12 October 2015 14:30:39 Jongsung Kim wrote:
> We tried to utilize a HW compressor as a zram backend. Current zram uses
> kmap_atomic to map a page, and the HW DMAes. So we needed to use
> kmap_atomic_to_page to get the page to be dma-mapped.

How about changing the zcomp code to pass the page pointer instead of
the kernel space pointer? That would avoid having to do the kmap_atomic,
which can itself be expensive on 32-bit machines and should not
be needed here if you have a HW DMA engine doing the compression.

	Arnd
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Thread

[PATCH] ARM:mm: fix kmap_atomic_to_page Chanho Min <chanho.min@lge.com> - 2015-10-06 13:30 +0200
  Re: [PATCH] ARM:mm: fix kmap_atomic_to_page Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-10-06 21:30 +0200
    Re: [PATCH] ARM:mm: fix kmap_atomic_to_page Nicolas Pitre <nicolas.pitre@linaro.org> - 2015-10-07 03:40 +0200
      Re: [PATCH] ARM:mm: fix kmap_atomic_to_page Jongsung Kim <neidhard.kim@lge.com> - 2015-10-07 06:20 +0200
        Re: [PATCH] ARM:mm: fix kmap_atomic_to_page Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-10-07 11:10 +0200
          Re: [PATCH] ARM:mm: fix kmap_atomic_to_page Jongsung Kim <neidhard.kim@lge.com> - 2015-10-12 07:40 +0200
            Re: [PATCH] ARM:mm: fix kmap_atomic_to_page Arnd Bergmann <arnd@arndb.de> - 2015-10-12 11:30 +0200
              Re: [PATCH] ARM:mm: fix kmap_atomic_to_page Jongsung Kim <neidhard.kim@lge.com> - 2015-10-13 04:10 +0200
                Re: [PATCH] ARM:mm: fix kmap_atomic_to_page Arnd Bergmann <arnd@arndb.de> - 2015-10-13 13:50 +0200
  Re: [PATCH] ARM:mm: fix kmap_atomic_to_page yalin wang <yalin.wang2010@gmail.com> - 2015-10-12 08:10 +0200

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