From: Li Chen <me@linux.beauty>
To: "Arnd Bergmann" <arnd@arndb.de>
Cc: "Catalin Marinas" <catalin.marinas@arm.com>,
"Will Deacon" <will@kernel.org>,
"Rob Herring" <robh+dt@kernel.org>,
"Frank Rowand" <frowand.list@gmail.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Li Chen" <lchen@ambarella.com>,
"Linux ARM" <linux-arm-kernel@lists.infradead.org>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
"DTML" <devicetree@vger.kernel.org>,
"Linux-MM" <linux-mm@kvack.org>
Subject: Re: [PATCH 4/4] sample/reserved_mem: Introduce a sample of struct page and dio support to no-map rmem
Date: Thu, 04 Aug 2022 16:17:45 +0900 [thread overview]
Message-ID: <18267b7a61f.12b26bd91245310.4476663913461696630@linux.beauty> (raw)
In-Reply-To: <CAK8P3a30o1RLifV1TMqDJ26vLhVdOzz3wP6yPrayLV2GPxUtwQ@mail.gmail.com>
Hi Arnd,
---- On Tue, 12 Jul 2022 16:50:46 +0900 Arnd Bergmann wrote ---
> Does your hardware require a fixed address for the buffer? If it can be
> anywhere in memory (or at least within a certain range) but just has to
> be physically contiguous, the normal way would be to use a CMA area
> to allocate from, which gives you 'struct page' backed pages.
CMA does support Direct I/O, but it has its own issue:
It does not guarantee that the memory previously borrowed by the OS will be returned to the device.
We've been plagued by examples like this in the past:
Many other kernel modules/subsystems have already allocated much memory from both non-CMA and CMA memory,
When our DSP driver got probed then, cma_alloc will fail in that non-CMA system memory is not enough
for CMA memory to migrate.
Regards,
Li
next prev parent reply other threads:[~2022-08-04 7:18 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-11 12:24 [PATCH 0/4] add struct page and Direct I/O support to reserved memory Li Chen
2022-07-11 12:24 ` [PATCH 1/4] of: add struct page support to rmem Li Chen
2022-07-11 13:36 ` Arnd Bergmann
2022-07-11 14:51 ` Li Chen
2022-07-11 15:06 ` Arnd Bergmann
2022-07-12 3:13 ` Li Chen
2022-07-16 0:38 ` kernel test robot
2022-07-18 13:21 ` Dan Carpenter
2022-07-11 12:24 ` [PATCH 2/4] mm/sparse: skip no-map memblock check when fill_subsection_map Li Chen
2022-07-11 14:53 ` David Hildenbrand
2022-07-12 4:23 ` Li Chen
2022-07-12 7:31 ` David Hildenbrand
2022-07-12 9:31 ` Li Chen
2022-07-14 18:45 ` kernel test robot
2022-07-11 12:24 ` [PATCH 3/4] arm64: mm: move memblock_clear_nomap after __add_pages Li Chen
2022-07-11 12:24 ` [PATCH 4/4] sample/reserved_mem: Introduce a sample of struct page and dio support to no-map rmem Li Chen
[not found] ` <CAK8P3a2Mr0ZMXGDx6htYEbBBtm4mubk-meSASJjPRK1j1O-hEA@mail.gmail.com>
2022-07-12 0:26 ` Li Chen
[not found] ` <CAK8P3a30o1RLifV1TMqDJ26vLhVdOzz3wP6yPrayLV2GPxUtwQ@mail.gmail.com>
2022-07-12 9:58 ` Li Chen
[not found] ` <CAK8P3a3gX-JMh6E2X3rH+U37zhkA6b0+AJDtXCJfdZiMocxLjg@mail.gmail.com>
2022-07-12 10:55 ` Li Chen
2022-08-04 7:17 ` Li Chen [this message]
[not found] ` <CAK8P3a0zSGqj3YEi+i9yfSLk8-aJtyiY6Bj069cxCdErk81+cw@mail.gmail.com>
2022-08-04 10:07 ` Li Chen
[not found] ` <CAK8P3a2hyhzjYqeL1LY7WziDjXQJasg3jFe83eErzKgbfP-a3w@mail.gmail.com>
2022-08-05 15:28 ` David Hildenbrand
2022-07-11 15:01 ` [PATCH 0/4] add struct page and Direct I/O support to reserved memory Christoph Hellwig
2022-07-11 16:05 ` Li Chen
2022-07-11 16:09 ` Christoph Hellwig
2022-07-12 0:14 ` Li Chen
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