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From: Christoph Hellwig <hch@lst.de>
To: Dan Williams <dan.j.williams@intel.com>
Cc: linux-nvdimm@lists.01.org, boaz@plexistor.com,
	david@fromorbit.com, linux-kernel@vger.kernel.org, hch@lst.de,
	linux-mm@kvack.org, hpa@zytor.com, ross.zwisler@linux.intel.com,
	mingo@kernel.org
Subject: Re: [PATCH v2 9/9] devm_memremap_pages: protect against pmem device unbind
Date: Wed, 26 Aug 2015 14:46:49 +0200	[thread overview]
Message-ID: <20150826124649.GA8014@lst.de> (raw)
In-Reply-To: <20150826012813.8851.35482.stgit@dwillia2-desk3.amr.corp.intel.com>

On Tue, Aug 25, 2015 at 09:28:13PM -0400, Dan Williams wrote:
> Given that:
> 
> 1/ device ->remove() can not be failed
> 
> 2/ a pmem device may be unbound at any time
> 
> 3/ we do not know what other parts of the kernel are actively using a
>    'struct page' from devm_memremap_pages()
> 
> ...provide a facility for active usages of device memory to block pmem
> device unbind.  With a percpu_ref it should be feasible to take a
> reference on a per-I/O or other high frequency basis.

Without a caller of get_page_map this is just adding dead code.  I'd
suggest to group it in a series with that caller.

Also if the page_map gets exposed in a header the name is a bit too generic.
memremap_map maybe?

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  reply	other threads:[~2015-08-26 12:46 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-08-26  1:27 [PATCH v2 0/9] initial struct page support for pmem Dan Williams
2015-08-26  1:27 ` [PATCH v2 1/9] dax: drop size parameter to ->direct_access() Dan Williams
2015-08-26  1:27 ` [PATCH v2 2/9] mm: move __phys_to_pfn and __pfn_to_phys to asm/generic/memory_model.h Dan Williams
2015-09-18 23:42   ` Tyler Baker
2015-09-18 23:59     ` Dan Williams
2015-09-19  6:49       ` Tyler Baker
2015-09-29 19:21   ` Nicolas Pitre
2015-09-29 19:36     ` Tyler Baker
2015-09-29 19:47       ` Nicolas Pitre
2015-08-26  1:27 ` [PATCH v2 3/9] mm: ZONE_DEVICE for "device memory" Dan Williams
2015-08-26  1:27 ` [PATCH v2 4/9] add devm_memremap_pages Dan Williams
2015-08-26  1:27 ` [PATCH v2 5/9] x86, pmem: push fallback handling to arch code Dan Williams
2015-08-26 12:41   ` Christoph Hellwig
2015-08-26 21:34     ` Williams, Dan J
2015-08-27  7:33       ` hch
2015-08-28 20:22       ` Ross Zwisler
2015-08-28 21:41       ` Toshi Kani
2015-08-28 21:47         ` Dan Williams
2015-08-28 21:48           ` Toshi Kani
2015-08-29  4:04             ` Williams, Dan J
2015-08-29 13:57               ` hch
2015-08-26  1:27 ` [PATCH v2 6/9] libnvdimm, pfn: 'struct page' provider infrastructure Dan Williams
2015-08-26  1:28 ` [PATCH v2 7/9] libnvdimm, pmem: 'struct page' for pmem Dan Williams
2015-08-26  1:28 ` [PATCH v2 8/9] libnvdimm, pmem: direct map legacy pmem by default Dan Williams
2015-08-26  1:28 ` [PATCH v2 9/9] devm_memremap_pages: protect against pmem device unbind Dan Williams
2015-08-26 12:46   ` Christoph Hellwig [this message]
2015-08-26 21:39     ` Williams, Dan J
2015-08-27  7:33       ` hch

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