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From: Minchan Kim <minchan@kernel.org>
To: Chulmin Kim <cmlaika.kim@samsung.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Subject: Re: [PATCH v7 11/12] zsmalloc: page migration support
Date: Wed, 25 Jan 2017 14:26:14 +0900
Message-ID: <20170125052614.GB18289@bbox> (raw)
In-Reply-To: <7488422b-98d1-1198-70d5-47c1e2bac721@samsung.com>

On Tue, Jan 24, 2017 at 11:06:51PM -0500, Chulmin Kim wrote:
> On 01/23/2017 12:40 AM, Minchan Kim wrote:
> >On Mon, Jan 23, 2017 at 02:30:56PM +0900, Sergey Senozhatsky wrote:
> >>On (01/23/17 14:22), Minchan Kim wrote:
> >>[..]
> >>>>Anyway, I will let you know the situation when it gets more clear.
> >>>
> >>>Yeb, Thanks.
> >>>
> >>>Perhaps, did you tried flush page before the writing?
> >>>I think arm64 have no d-cache alising problem but worth to try it.
> >>>Who knows :)
> >>
> >>I thought that flush_dcache_page() is only for cases when we write
> >>to page (store that makes pages dirty), isn't it?
> >
> >I think we need both because to see recent stores done by the user.
> >I'm not sure it should be done by block device driver rather than
> >page cache. Anyway, brd added it so worth to try it, I thought. :)
> >
> 
> Thanks for the suggestion!
> It might be helpful
> though proving it is not easy as the problem appears rarely.
> 
> Have you thought about
> zram swap or zswap dealing with self modifying code pages (ex. JIT)?
> (arm64 may have i-cache aliasing problem)

It can happen, I think, although I don't know how arm64 handles it.

> 
> If it is problematic,
> especiallly zswap (without flush_dcache_page in zswap_frontswap_load()) may
> provide the corrupted data
> and even swap out (compressing) may see the corrupted data sooner or later,
> i guess.

try_to_unmap_one calls flush_cache_page which I hope to handle swap-out side
but for swap-in, I think zswap need flushing logic because it's first
touch of the user buffer so it's his resposibility.

Thanks.

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  parent reply index

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-05-31 23:21 [PATCH v7 00/12] Support non-lru page migration Minchan Kim
2016-05-31 23:21 ` [PATCH v7 01/12] mm: use put_page to free page instead of putback_lru_page Minchan Kim
2016-05-31 23:21 ` [PATCH v7 02/12] mm: migrate: support non-lru movable page migration Minchan Kim
2016-05-31 23:21 ` [PATCH v7 03/12] mm: balloon: use general non-lru movable page feature Minchan Kim
2016-05-31 23:21 ` [PATCH v7 04/12] zsmalloc: keep max_object in size_class Minchan Kim
2016-05-31 23:21 ` [PATCH v7 05/12] zsmalloc: use bit_spin_lock Minchan Kim
2016-05-31 23:21 ` [PATCH v7 06/12] zsmalloc: use accessor Minchan Kim
2016-05-31 23:21 ` [PATCH v7 07/12] zsmalloc: factor page chain functionality out Minchan Kim
2016-05-31 23:21 ` [PATCH v7 08/12] zsmalloc: introduce zspage structure Minchan Kim
2016-05-31 23:21 ` [PATCH v7 09/12] zsmalloc: separate free_zspage from putback_zspage Minchan Kim
2016-05-31 23:21 ` [PATCH v7 10/12] zsmalloc: use freeobj for index Minchan Kim
2016-05-31 23:21 ` [PATCH v7 11/12] zsmalloc: page migration support Minchan Kim
2016-06-01 14:09   ` Vlastimil Babka
2016-06-02  0:25     ` Minchan Kim
2016-06-02 11:44       ` Vlastimil Babka
2016-06-01 21:39   ` Andrew Morton
2016-06-02  0:15     ` Minchan Kim
     [not found]   ` <CGME20170119001317epcas1p188357c77e1f4ff08b6d3dcb76dedca06@epcas1p1.samsung.com>
2017-01-19  0:13     ` Chulmin Kim
2017-01-19  2:44       ` Minchan Kim
2017-01-19  3:39         ` Chulmin Kim
2017-01-19  6:21           ` Minchan Kim
2017-01-19  8:16             ` Chulmin Kim
2017-01-23  5:22               ` Minchan Kim
2017-01-23  5:30                 ` Sergey Senozhatsky
2017-01-23  5:40                   ` Minchan Kim
2017-01-25  4:06                     ` Chulmin Kim
2017-01-25  4:25                       ` Sergey Senozhatsky
2017-01-25  5:26                       ` Minchan Kim [this message]
2017-01-26 17:04                         ` Dan Streetman
2017-01-31  0:10                           ` Minchan Kim
2017-01-31 13:09                             ` Dan Streetman
2017-02-01  6:51                               ` Minchan Kim
2017-02-01 19:38                                 ` Dan Streetman
2017-02-02  8:48                               ` Minchan Kim
2016-05-31 23:21 ` [PATCH v7 12/12] zram: use __GFP_MOVABLE for memory allocation Minchan Kim
2016-06-01 21:41 ` [PATCH v7 00/12] Support non-lru page migration Andrew Morton
2016-06-01 22:40   ` Daniel Vetter
2016-06-02  0:36   ` Minchan Kim
2016-06-15  7:59 ` Sergey Senozhatsky
2016-06-15 23:12   ` Minchan Kim
2016-06-16  2:48     ` Sergey Senozhatsky
2016-06-16  2:58       ` Minchan Kim
2016-06-16  4:23         ` Sergey Senozhatsky
2016-06-16  4:47           ` Minchan Kim
2016-06-16  5:22             ` Sergey Senozhatsky
2016-06-16  6:47               ` Minchan Kim
2016-06-16  8:42                 ` Sergey Senozhatsky
2016-06-16 10:09                   ` Minchan Kim
2016-06-17  7:28                     ` Joonsoo Kim

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