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From: Yin Fengwei <fengwei.yin@intel.com>
To: Yu Zhao <yuzhao@google.com>
Cc: <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
	<akpm@linux-foundation.org>, <willy@infradead.org>,
	<david@redhat.com>, <ryan.roberts@arm.com>, <shy828301@gmail.com>
Subject: Re: [RFC PATCH v2 3/3] mm: mlock: update mlock_pte_range to handle large folio
Date: Mon, 17 Jul 2023 09:58:39 +0800	[thread overview]
Message-ID: <16844254-7248-f557-b1eb-b8b102c877a2@intel.com> (raw)
In-Reply-To: <CAOUHufZHyEvU-c2O6B6stM_QVMxc22zV4Szn52myYqjdZvptUA@mail.gmail.com>



On 7/17/23 08:35, Yu Zhao wrote:
> On Sun, Jul 16, 2023 at 6:00 PM Yin, Fengwei <fengwei.yin@intel.com> wrote:
>>
>> On 7/15/2023 2:06 PM, Yu Zhao wrote:
>>> There is a problem here that I didn't have the time to elaborate: we
>>> can't mlock() a folio that is within the range but not fully mapped
>>> because this folio can be on the deferred split queue. When the split
>>> happens, those unmapped folios (not mapped by this vma but are mapped
>>> into other vmas) will be stranded on the unevictable lru.
>>
>> This should be fine unless I missed something. During large folio split,
>> the unmap_folio() will be migrate(anon)/unmap(file) folio. Folio will be
>> munlocked in unmap_folio(). So the head/tail pages will be evictable always.
> 
> It's close but not entirely accurate: munlock can fail on isolated folios.
Yes. The munlock just clear PG_mlocked bit but with PG_unevictable left.

Could this also happen against normal 4K page? I mean when user try to munlock
a normal 4K page and this 4K page is isolated. So it become unevictable page?


Regards
Yin, Fengwei

  reply	other threads:[~2023-07-17  1:58 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-07-12  6:01 [RFC PATCH v2 0/3] support large folio for mlock Yin Fengwei
2023-07-12  6:01 ` [RFC PATCH v2 1/3] mm: add functions folio_in_range() and folio_within_vma() Yin Fengwei
2023-07-12  6:11   ` Yu Zhao
2023-07-12  6:01 ` [RFC PATCH v2 2/3] mm: handle large folio when large folio in VM_LOCKED VMA range Yin Fengwei
2023-07-12  6:23   ` Yu Zhao
2023-07-12  6:43     ` Yin Fengwei
2023-07-12 17:03       ` Yu Zhao
2023-07-13  1:55         ` Yin Fengwei
2023-07-14  2:21       ` Hugh Dickins
2023-07-14  2:49         ` Yin, Fengwei
2023-07-14  3:41           ` Hugh Dickins
2023-07-14  5:45             ` Yin, Fengwei
2023-07-12  6:01 ` [RFC PATCH v2 3/3] mm: mlock: update mlock_pte_range to handle large folio Yin Fengwei
2023-07-12  6:31   ` Yu Zhao
2023-07-15  6:06     ` Yu Zhao
2023-07-16 23:59       ` Yin, Fengwei
2023-07-17  0:35         ` Yu Zhao
2023-07-17  1:58           ` Yin Fengwei [this message]
2023-07-18 22:48             ` Yosry Ahmed
2023-07-18 23:47               ` Yin Fengwei
2023-07-19  1:32                 ` Yosry Ahmed
2023-07-19  1:52                   ` Yosry Ahmed
2023-07-19  1:57                     ` Yin Fengwei
2023-07-19  2:00                       ` Yosry Ahmed
2023-07-19  2:09                         ` Yin Fengwei
2023-07-19  2:22                           ` Yosry Ahmed
2023-07-19  2:28                             ` Yin Fengwei
2023-07-19 14:26                               ` Hugh Dickins
2023-07-19 15:44                                 ` Yosry Ahmed
2023-07-20 12:02                                   ` Yin, Fengwei
2023-07-20 20:51                                     ` Yosry Ahmed
2023-07-21  1:12                                       ` Yin, Fengwei
2023-07-21  1:35                                         ` Yosry Ahmed
2023-07-21  3:18                                           ` Yin, Fengwei
2023-07-21  3:39                                             ` Yosry Ahmed
2023-07-20  1:52                                 ` Yin, Fengwei
2023-07-17  8:12           ` Yin Fengwei
2023-07-18  2:06             ` Yin Fengwei
2023-07-18  3:59               ` Yu Zhao
2023-07-26 12:49       ` Yin Fengwei
2023-07-26 16:57         ` Yu Zhao
2023-07-27  0:15           ` Yin Fengwei

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