From: Felix Kuehling <felix.kuehling@amd.com>
To: David Hildenbrand <david@redhat.com>,
Alex Sierra <alex.sierra@amd.com>,
jgg@nvidia.com
Cc: linux-mm@kvack.org, rcampbell@nvidia.com,
linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org,
amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
hch@lst.de, jglisse@redhat.com, apopple@nvidia.com,
willy@infradead.org, akpm@linux-foundation.org
Subject: Re: [PATCH] mm: split vm_normal_pages for LRU and non-LRU handling
Date: Tue, 1 Mar 2022 11:08:50 -0500 [thread overview]
Message-ID: <41469645-55be-1aaa-c1ef-84a123fdb4ea@amd.com> (raw)
In-Reply-To: <2a042493-d04d-41b1-ea12-b326d2116861@redhat.com>
Am 2022-03-01 um 03:03 schrieb David Hildenbrand:
> On 28.02.22 21:34, Alex Sierra wrote:
>> DEVICE_COHERENT pages introduce a subtle distinction in the way
>> "normal" pages can be used by various callers throughout the kernel.
>> They behave like normal pages for purposes of mapping in CPU page
>> tables, and for COW. But they do not support LRU lists, NUMA
>> migration or THP. Therefore we split vm_normal_page into two
>> functions vm_normal_any_page and vm_normal_lru_page. The latter will
>> only return pages that can be put on an LRU list and that support
>> NUMA migration and THP.
> Why not s/vm_normal_any_page/vm_normal_page/ and avoid code churn?
I don't care much, personally, what names we end up with. I'll wait for
a consensus here.
>
>> We also introduced a FOLL_LRU flag that adds the same behaviour to
>> follow_page and related APIs, to allow callers to specify that they
>> expect to put pages on an LRU list.
> [...]
>> -#define FOLL_WRITE 0x01 /* check pte is writable */
>> -#define FOLL_TOUCH 0x02 /* mark page accessed */
>> -#define FOLL_GET 0x04 /* do get_page on page */
>> -#define FOLL_DUMP 0x08 /* give error on hole if it would be zero */
>> -#define FOLL_FORCE 0x10 /* get_user_pages read/write w/o permission */
>> -#define FOLL_NOWAIT 0x20 /* if a disk transfer is needed, start the IO
>> - * and return without waiting upon it */
>> -#define FOLL_POPULATE 0x40 /* fault in pages (with FOLL_MLOCK) */
>> -#define FOLL_NOFAULT 0x80 /* do not fault in pages */
>> -#define FOLL_HWPOISON 0x100 /* check page is hwpoisoned */
>> -#define FOLL_NUMA 0x200 /* force NUMA hinting page fault */
>> -#define FOLL_MIGRATION 0x400 /* wait for page to replace migration entry */
>> -#define FOLL_TRIED 0x800 /* a retry, previous pass started an IO */
>> -#define FOLL_MLOCK 0x1000 /* lock present pages */
>> -#define FOLL_REMOTE 0x2000 /* we are working on non-current tsk/mm */
>> -#define FOLL_COW 0x4000 /* internal GUP flag */
>> -#define FOLL_ANON 0x8000 /* don't do file mappings */
>> -#define FOLL_LONGTERM 0x10000 /* mapping lifetime is indefinite: see below */
>> -#define FOLL_SPLIT_PMD 0x20000 /* split huge pmd before returning */
>> -#define FOLL_PIN 0x40000 /* pages must be released via unpin_user_page */
>> -#define FOLL_FAST_ONLY 0x80000 /* gup_fast: prevent fall-back to slow gup */
>> +#define FOLL_WRITE 0x01 /* check pte is writable */
>> +#define FOLL_TOUCH 0x02 /* mark page accessed */
>> +#define FOLL_GET 0x04 /* do get_page on page */
>> +#define FOLL_DUMP 0x08 /* give error on hole if it would be zero */
>> +#define FOLL_FORCE 0x10 /* get_user_pages read/write w/o permission */
>> +#define FOLL_NOWAIT 0x20 /* if a disk transfer is needed, start the IO
>> + * and return without waiting upon it */
>> +#define FOLL_POPULATE 0x40 /* fault in pages (with FOLL_MLOCK) */
>> +#define FOLL_NOFAULT 0x80 /* do not fault in pages */
>> +#define FOLL_HWPOISON 0x100 /* check page is hwpoisoned */
>> +#define FOLL_NUMA 0x200 /* force NUMA hinting page fault */
>> +#define FOLL_MIGRATION 0x400 /* wait for page to replace migration entry */
>> +#define FOLL_TRIED 0x800 /* a retry, previous pass started an IO */
>> +#define FOLL_MLOCK 0x1000 /* lock present pages */
>> +#define FOLL_REMOTE 0x2000 /* we are working on non-current tsk/mm */
>> +#define FOLL_COW 0x4000 /* internal GUP flag */
>> +#define FOLL_ANON 0x8000 /* don't do file mappings */
>> +#define FOLL_LONGTERM 0x10000 /* mapping lifetime is indefinite: see below */
>> +#define FOLL_SPLIT_PMD 0x20000 /* split huge pmd before returning */
>> +#define FOLL_PIN 0x40000 /* pages must be released via unpin_user_page */
>> +#define FOLL_FAST_ONLY 0x80000 /* gup_fast: prevent fall-back to slow gup */
>> +#define FOLL_LRU 0x100000 /* return only LRU (anon or page cache) */
>>
> Can we minimize code churn, please?
OK. I guess we could unindent the FOLL_LRU number to avoid changing all
the comments.
>
>
>> if (PageReserved(page))
>> diff --git a/mm/migrate.c b/mm/migrate.c
>> index c31d04b46a5e..17d049311b78 100644
>> --- a/mm/migrate.c
>> +++ b/mm/migrate.c
>> @@ -1614,7 +1614,7 @@ static int add_page_for_migration(struct mm_struct *mm, unsigned long addr,
>> goto out;
>>
>> /* FOLL_DUMP to ignore special (like zero) pages */
>> - follflags = FOLL_GET | FOLL_DUMP;
>> + follflags = FOLL_GET | FOLL_DUMP | FOLL_LRU;
>> page = follow_page(vma, addr, follflags);
> Why wouldn't we want to dump DEVICE_COHERENT pages? This looks wrong.
This function later calls isolate_lru_page, which is something you can't
do with a device page.
Regards,
Felix
>
next prev parent reply other threads:[~2022-03-01 16:08 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-01 15:48 [PATCH v6 00/10] Add MEMORY_DEVICE_COHERENT for coherent device memory mapping Alex Sierra
2022-02-01 15:48 ` [PATCH v6 01/10] mm: add zone device coherent type memory support Alex Sierra
2022-02-11 16:15 ` David Hildenbrand
2022-02-11 16:39 ` David Hildenbrand
2022-02-11 16:52 ` Sierra Guiza, Alejandro (Alex)
2022-02-11 17:07 ` Felix Kuehling
2022-02-15 12:16 ` David Hildenbrand
2022-02-15 14:45 ` Jason Gunthorpe
2022-02-15 18:32 ` Christoph Hellwig
2022-02-15 19:41 ` Jason Gunthorpe
2022-02-15 21:35 ` Felix Kuehling
2022-02-15 21:47 ` Jason Gunthorpe
2022-02-15 22:49 ` Felix Kuehling
2022-02-16 2:01 ` Jason Gunthorpe
2022-02-16 16:56 ` Felix Kuehling
2022-02-16 17:28 ` Jason Gunthorpe
2022-02-16 1:23 ` Alistair Popple
2022-02-16 2:03 ` Jason Gunthorpe
2022-02-16 2:36 ` Alistair Popple
2022-02-16 8:31 ` David Hildenbrand
2022-02-16 12:26 ` Jason Gunthorpe
2022-02-17 1:05 ` Alistair Popple
2022-02-17 21:12 ` Felix Kuehling
2022-02-18 0:19 ` Jason Gunthorpe
2022-02-18 19:20 ` Felix Kuehling
2022-02-18 19:26 ` Jason Gunthorpe
2022-02-18 19:37 ` Felix Kuehling
2022-02-28 20:34 ` [PATCH] mm: split vm_normal_pages for LRU and non-LRU handling Alex Sierra
2022-02-28 22:41 ` Felix Kuehling
2022-03-01 8:03 ` David Hildenbrand
2022-03-01 16:08 ` Felix Kuehling [this message]
2022-03-01 16:22 ` David Hildenbrand
2022-03-01 16:30 ` Felix Kuehling
2022-03-01 16:32 ` David Hildenbrand
2022-02-18 0:59 ` [PATCH v6 01/10] mm: add zone device coherent type memory support Alistair Popple
2022-02-11 16:45 ` Jason Gunthorpe
2022-02-11 16:49 ` David Hildenbrand
2022-02-11 16:56 ` Jason Gunthorpe
2022-02-15 12:15 ` David Hildenbrand
2022-02-15 18:52 ` Felix Kuehling
2022-02-11 17:05 ` Felix Kuehling
2022-02-14 2:04 ` Alistair Popple
2022-02-01 15:48 ` [PATCH v6 02/10] mm: add device coherent vma selection for memory migration Alex Sierra
2022-02-01 15:48 ` [PATCH v6 03/10] mm/gup: fail get_user_pages for LONGTERM dev coherent type Alex Sierra
2022-02-01 15:48 ` [PATCH v6 04/10] drm/amdkfd: add SPM support for SVM Alex Sierra
2022-02-01 15:48 ` [PATCH v6 05/10] drm/amdkfd: coherent type as sys mem on migration to ram Alex Sierra
2022-02-01 15:48 ` [PATCH v6 06/10] lib: test_hmm add ioctl to get zone device type Alex Sierra
2022-02-01 15:48 ` [PATCH v6 07/10] lib: test_hmm add module param for " Alex Sierra
2022-02-01 15:48 ` [PATCH v6 08/10] lib: add support for device coherent type in test_hmm Alex Sierra
2022-02-01 15:49 ` [PATCH v6 09/10] tools: update hmm-test to support device coherent type Alex Sierra
2022-02-01 15:49 ` [PATCH v6 10/10] tools: update test_hmm script to support SP config Alex Sierra
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