From: Anshuman Khandual <khandual@linux.vnet.ibm.com>
To: Minchan Kim <minchan@kernel.org>,
Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Rik van Riel <riel@redhat.com>, Vlastimil Babka <vbabka@suse.cz>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Mel Gorman <mgorman@suse.de>, Hugh Dickins <hughd@google.com>,
Rafael Aquini <aquini@redhat.com>,
virtualization@lists.linux-foundation.org,
Jonathan Corbet <corbet@lwn.net>,
John Einar Reitan <john.reitan@foss.arm.com>,
dri-devel@lists.freedesktop.org,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Gioh Kim <gi-oh.kim@profitbricks.com>
Subject: Re: [PATCH v6v3 02/12] mm: migrate: support non-lru movable page migration
Date: Mon, 27 Jun 2016 11:21:01 +0530 [thread overview]
Message-ID: <5770BEC5.3010807@linux.vnet.ibm.com> (raw)
In-Reply-To: <20160616053754.GQ17127@bbox>
On 06/16/2016 11:07 AM, Minchan Kim wrote:
> On Thu, Jun 16, 2016 at 09:12:07AM +0530, Anshuman Khandual wrote:
>> On 06/16/2016 05:56 AM, Minchan Kim wrote:
>>> On Wed, Jun 15, 2016 at 12:15:04PM +0530, Anshuman Khandual wrote:
>>>> On 06/15/2016 08:02 AM, Minchan Kim wrote:
>>>>> Hi,
>>>>>
>>>>> On Mon, Jun 13, 2016 at 03:08:19PM +0530, Anshuman Khandual wrote:
>>>>>>> On 05/31/2016 05:31 AM, Minchan Kim wrote:
>>>>>>>>> @@ -791,6 +921,7 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
>>>>>>>>> int rc = -EAGAIN;
>>>>>>>>> int page_was_mapped = 0;
>>>>>>>>> struct anon_vma *anon_vma = NULL;
>>>>>>>>> + bool is_lru = !__PageMovable(page);
>>>>>>>>>
>>>>>>>>> if (!trylock_page(page)) {
>>>>>>>>> if (!force || mode == MIGRATE_ASYNC)
>>>>>>>>> @@ -871,6 +1002,11 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
>>>>>>>>> goto out_unlock_both;
>>>>>>>>> }
>>>>>>>>>
>>>>>>>>> + if (unlikely(!is_lru)) {
>>>>>>>>> + rc = move_to_new_page(newpage, page, mode);
>>>>>>>>> + goto out_unlock_both;
>>>>>>>>> + }
>>>>>>>>> +
>>>>>>>
>>>>>>> Hello Minchan,
>>>>>>>
>>>>>>> I might be missing something here but does this implementation support the
>>>>>>> scenario where these non LRU pages owned by the driver mapped as PTE into
>>>>>>> process page table ? Because the "goto out_unlock_both" statement above
>>>>>>> skips all the PTE unmap, putting a migration PTE and removing the migration
>>>>>>> PTE steps.
>>>>> You're right. Unfortunately, it doesn't support right now but surely,
>>>>> it's my TODO after landing this work.
>>>>>
>>>>> Could you share your usecase?
>>>>
>>>> Sure.
>>>
>>> Thanks a lot!
>>>
>>>>
>>>> My driver has privately managed non LRU pages which gets mapped into user space
>>>> process page table through f_ops->mmap() and vmops->fault() which then updates
>>>> the file RMAP (page->mapping->i_mmap) through page_add_file_rmap(page). One thing
>>>
>>> Hmm, page_add_file_rmap is not exported function. How does your driver can use it?
>>
>> Its not using the function directly, I just re-iterated the sequence of functions
>> above. (do_set_pte -> page_add_file_rmap) gets called after we grab the page from
>> driver through (__do_fault->vma->vm_ops->fault()).
>>
>>> Do you use vm_insert_pfn?
>>> What type your vma is? VM_PFNMMAP or VM_MIXEDMAP?
>>
>> I dont use vm_insert_pfn(). Here is the sequence of events how the user space
>> VMA gets the non LRU pages from the driver.
>>
>> - Driver registers a character device with 'struct file_operations' binding
>> - Then the 'fops->mmap()' just binds the incoming 'struct vma' with a 'struct
>> vm_operations_struct' which provides the 'vmops->fault()' routine which
>> basically traps all page faults on the VMA and provides one page at a time
>> through a driver specific allocation routine which hands over non LRU pages
>>
>> The VMA is not anything special as such. Its what we get when we try to do a
>> simple mmap() on a file descriptor pointing to a character device. I can
>> figure out all the VM_* flags it holds after creation.
>>
>>>
>>> I want to make dummy driver to simulate your case.
>>
>> Sure. I hope the above mentioned steps will help you but in case you need more
>> information, please do let me know.
>
> I got understood now. :)
> I will test it with dummy driver and will Cc'ed when I send a patch.
Hello Minchan,
Do you have any updates on this ? The V7 of the series still has this limitation.
Did you get a chance to test the driver out ? I am still concerned about how to
handle the struct address_space override problem within the struct page.
- Anshuman
next prev parent reply other threads:[~2016-06-27 5:51 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-20 14:23 [PATCH v6 00/12] Support non-lru page migration Minchan Kim
2016-05-20 14:23 ` [PATCH v6 01/12] mm: use put_page to free page instead of putback_lru_page Minchan Kim
2016-05-20 14:23 ` [PATCH v6 02/12] mm: migrate: support non-lru movable page migration Minchan Kim
2016-05-27 14:26 ` Vlastimil Babka
2016-05-30 1:33 ` Minchan Kim
2016-05-30 9:01 ` Vlastimil Babka
2016-05-30 1:39 ` PATCH v6v2 " Minchan Kim
2016-05-30 9:36 ` Vlastimil Babka
2016-05-30 16:25 ` Minchan Kim
2016-05-31 7:51 ` Vlastimil Babka
2016-05-31 0:01 ` [PATCH v6v3 " Minchan Kim
2016-05-31 7:52 ` Vlastimil Babka
2016-05-31 23:05 ` Minchan Kim
2016-06-13 9:38 ` Anshuman Khandual
2016-06-15 2:32 ` Minchan Kim
2016-06-15 6:45 ` Anshuman Khandual
2016-06-16 0:26 ` Minchan Kim
2016-06-16 3:42 ` Anshuman Khandual
2016-06-16 5:37 ` Minchan Kim
2016-06-27 5:51 ` Anshuman Khandual [this message]
2016-06-28 6:39 ` Minchan Kim
2016-06-30 5:56 ` Anshuman Khandual
2016-06-30 6:18 ` Minchan Kim
2016-05-20 14:23 ` [PATCH v6 03/12] mm: balloon: use general non-lru movable page feature Minchan Kim
2016-05-30 12:16 ` Vlastimil Babka
2016-05-20 14:23 ` [PATCH v6 04/12] zsmalloc: keep max_object in size_class Minchan Kim
2016-05-20 14:23 ` [PATCH v6 05/12] zsmalloc: use bit_spin_lock Minchan Kim
2016-05-20 14:23 ` [PATCH v6 06/12] zsmalloc: use accessor Minchan Kim
2016-05-20 14:23 ` [PATCH v6 07/12] zsmalloc: factor page chain functionality out Minchan Kim
2016-05-20 14:23 ` [PATCH v6 08/12] zsmalloc: introduce zspage structure Minchan Kim
2016-05-20 14:23 ` [PATCH v6 09/12] zsmalloc: separate free_zspage from putback_zspage Minchan Kim
2016-05-20 14:23 ` [PATCH v6 10/12] zsmalloc: use freeobj for index Minchan Kim
2016-05-20 14:23 ` [PATCH v6 11/12] zsmalloc: page migration support Minchan Kim
2016-05-24 5:28 ` Sergey Senozhatsky
2016-05-24 6:28 ` Minchan Kim
2016-05-24 8:05 ` Sergey Senozhatsky
2016-05-24 8:17 ` Minchan Kim
2016-05-25 5:14 ` Minchan Kim
2016-05-25 15:23 ` Sergey Senozhatsky
2016-05-26 0:32 ` Minchan Kim
2016-05-26 0:59 ` Sergey Senozhatsky
2016-05-26 4:37 ` Minchan Kim
2016-05-26 21:50 ` [PATCH v6r2 " Minchan Kim
2016-05-20 14:23 ` [PATCH v6 12/12] zram: use __GFP_MOVABLE for memory allocation Minchan Kim
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