From: John Hubbard <jhubbard@nvidia.com>
To: "Andrew Morton" <akpm@linux-foundation.org>,
"Jérôme Glisse" <jglisse@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
David Nellans <dnellans@nvidia.com>,
Evgeny Baskakov <ebaskakov@nvidia.com>,
Mark Hairgrove <mhairgrove@nvidia.com>,
Sherry Cheung <SCheung@nvidia.com>,
Subhash Gutti <sgutti@nvidia.com>
Subject: Re: [HMM 07/16] mm/migrate: new memory migration helper for use with device memory v4
Date: Thu, 16 Mar 2017 17:22:51 -0700 [thread overview]
Message-ID: <d4e8433d-4680-dced-4f11-2f3cc8ebc613@nvidia.com> (raw)
In-Reply-To: <20170316160520.d03ac02474cad6d2c8eba9bc@linux-foundation.org>
On 03/16/2017 04:05 PM, Andrew Morton wrote:
> On Thu, 16 Mar 2017 12:05:26 -0400 Jérôme Glisse <jglisse@redhat.com> wrote:
>
>> +static inline struct page *migrate_pfn_to_page(unsigned long mpfn)
>> +{
>> + if (!(mpfn & MIGRATE_PFN_VALID))
>> + return NULL;
>> + return pfn_to_page(mpfn & MIGRATE_PFN_MASK);
>> +}
>
> i386 allnoconfig:
>
> In file included from mm/page_alloc.c:61:
> ./include/linux/migrate.h: In function 'migrate_pfn_to_page':
> ./include/linux/migrate.h:139: warning: left shift count >= width of type
> ./include/linux/migrate.h:141: warning: left shift count >= width of type
> ./include/linux/migrate.h: In function 'migrate_pfn_size':
> ./include/linux/migrate.h:146: warning: left shift count >= width of type
>
It seems clear that this was never meant to work with < 64-bit pfns:
// migrate.h excerpt:
#define MIGRATE_PFN_VALID (1UL << (BITS_PER_LONG_LONG - 1))
#define MIGRATE_PFN_MIGRATE (1UL << (BITS_PER_LONG_LONG - 2))
#define MIGRATE_PFN_HUGE (1UL << (BITS_PER_LONG_LONG - 3))
#define MIGRATE_PFN_LOCKED (1UL << (BITS_PER_LONG_LONG - 4))
#define MIGRATE_PFN_WRITE (1UL << (BITS_PER_LONG_LONG - 5))
#define MIGRATE_PFN_DEVICE (1UL << (BITS_PER_LONG_LONG - 6))
#define MIGRATE_PFN_ERROR (1UL << (BITS_PER_LONG_LONG - 7))
#define MIGRATE_PFN_MASK ((1UL << (BITS_PER_LONG_LONG - PAGE_SHIFT)) - 1)
...obviously, there is not enough room for these flags, in a 32-bit pfn.
So, given the current HMM design, I think we are going to have to provide a 32-bit version of these
routines (migrate_pfn_to_page, and related) that is a no-op, right?
thanks
John Hubbard
NVIDIA
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next prev parent reply other threads:[~2017-03-17 0:22 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-16 16:05 [HMM 00/16] HMM (Heterogeneous Memory Management) v18 Jérôme Glisse
2017-03-16 16:05 ` [HMM 01/16] mm/memory/hotplug: convert device bool to int to allow for more flags v3 Jérôme Glisse
2017-03-19 20:08 ` Mel Gorman
2017-03-16 16:05 ` [HMM 02/16] mm/put_page: move ref decrement to put_zone_device_page() Jérôme Glisse
2017-03-19 20:08 ` Mel Gorman
2017-03-16 16:05 ` [HMM 03/16] mm/ZONE_DEVICE/free-page: callback when page is freed v3 Jérôme Glisse
2017-03-19 20:08 ` Mel Gorman
2017-03-16 16:05 ` [HMM 04/16] mm/ZONE_DEVICE/unaddressable: add support for un-addressable device memory v3 Jérôme Glisse
2017-03-19 20:09 ` Mel Gorman
2017-03-16 16:05 ` [HMM 05/16] mm/ZONE_DEVICE/x86: add support for un-addressable device memory Jérôme Glisse
2017-03-16 16:05 ` [HMM 06/16] mm/migrate: add new boolean copy flag to migratepage() callback Jérôme Glisse
2017-03-19 20:09 ` Mel Gorman
2017-03-16 16:05 ` [HMM 07/16] mm/migrate: new memory migration helper for use with device memory v4 Jérôme Glisse
2017-03-16 16:24 ` Reza Arbab
2017-03-16 20:58 ` Balbir Singh
2017-03-16 23:05 ` Andrew Morton
2017-03-17 0:22 ` John Hubbard [this message]
2017-03-17 0:45 ` Balbir Singh
2017-03-17 0:57 ` John Hubbard
2017-03-17 1:52 ` Jerome Glisse
2017-03-17 3:32 ` Andrew Morton
2017-03-17 3:42 ` Balbir Singh
2017-03-17 4:51 ` Balbir Singh
2017-03-17 7:17 ` John Hubbard
2017-03-16 16:05 ` [HMM 08/16] mm/migrate: migrate_vma() unmap page from vma while collecting pages Jérôme Glisse
2017-03-16 16:05 ` [HMM 09/16] mm/hmm: heterogeneous memory management (HMM for short) Jérôme Glisse
2017-03-19 20:09 ` Mel Gorman
2017-03-16 16:05 ` [HMM 10/16] mm/hmm/mirror: mirror process address space on device with HMM helpers Jérôme Glisse
2017-03-19 20:09 ` Mel Gorman
2017-03-16 16:05 ` [HMM 11/16] mm/hmm/mirror: helper to snapshot CPU page table v2 Jérôme Glisse
2017-03-19 20:09 ` Mel Gorman
2017-03-16 16:05 ` [HMM 12/16] mm/hmm/mirror: device page fault handler Jérôme Glisse
2017-03-16 16:05 ` [HMM 13/16] mm/hmm/migrate: support un-addressable ZONE_DEVICE page in migration Jérôme Glisse
2017-03-16 16:05 ` [HMM 14/16] mm/migrate: allow migrate_vma() to alloc new page on empty entry Jérôme Glisse
2017-03-16 16:05 ` [HMM 15/16] mm/hmm/devmem: device memory hotplug using ZONE_DEVICE Jérôme Glisse
2017-03-16 16:05 ` [HMM 16/16] mm/hmm/devmem: dummy HMM device for ZONE_DEVICE memory v2 Jérôme Glisse
2017-03-17 6:55 ` Bob Liu
2017-03-17 16:53 ` Jerome Glisse
2017-03-16 20:43 ` [HMM 00/16] HMM (Heterogeneous Memory Management) v18 Andrew Morton
2017-03-16 23:49 ` Jerome Glisse
2017-03-17 8:29 ` Bob Liu
2017-03-17 15:57 ` Jerome Glisse
2017-03-17 8:39 ` Bob Liu
2017-03-17 15:52 ` Jerome Glisse
2017-03-19 20:09 ` Mel Gorman
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