From: Vlastimil Babka <vbabka@suse.cz>
To: Minchan Kim <minchan@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
jlayton@poochiereds.net, bfields@fieldses.org,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
koct9i@gmail.com, aquini@redhat.com,
virtualization@lists.linux-foundation.org,
Mel Gorman <mgorman@suse.de>, Hugh Dickins <hughd@google.com>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Rik van Riel <riel@redhat.com>,
rknize@motorola.com, Gioh Kim <gi-oh.kim@profitbricks.com>,
Sangseok Lee <sangseok.lee@lge.com>,
Chan Gyun Jeong <chan.jeong@lge.com>,
Al Viro <viro@ZenIV.linux.org.uk>,
YiPing Xu <xuyiping@hisilicon.com>,
Gioh Kim <gurugio@hanmail.net>
Subject: Re: [PATCH v3 04/16] mm/balloon: use general movable page feature into balloon
Date: Tue, 5 Apr 2016 14:03:05 +0200 [thread overview]
Message-ID: <5703A979.402@suse.cz> (raw)
In-Reply-To: <1459321935-3655-5-git-send-email-minchan@kernel.org>
On 03/30/2016 09:12 AM, Minchan Kim wrote:
> Now, VM has a feature to migrate non-lru movable pages so
> balloon doesn't need custom migration hooks in migrate.c
> and compact.c. Instead, this patch implements page->mapping
> ->{isolate|migrate|putback} functions.
>
> With that, we could remove hooks for ballooning in general
> migration functions and make balloon compaction simple.
>
> Cc: virtualization@lists.linux-foundation.org
> Cc: Rafael Aquini <aquini@redhat.com>
> Cc: Konstantin Khlebnikov <koct9i@gmail.com>
> Signed-off-by: Gioh Kim <gurugio@hanmail.net>
> Signed-off-by: Minchan Kim <minchan@kernel.org>
I'm not familiar with the inode and pseudofs stuff, so just some things
I noticed:
> -#define PAGE_MOVABLE_MAPCOUNT_VALUE (-255)
> +#define PAGE_MOVABLE_MAPCOUNT_VALUE (-256)
> +#define PAGE_BALLOON_MAPCOUNT_VALUE PAGE_MOVABLE_MAPCOUNT_VALUE
>
> static inline int PageMovable(struct page *page)
> {
> - return ((test_bit(PG_movable, &(page)->flags) &&
> - atomic_read(&page->_mapcount) == PAGE_MOVABLE_MAPCOUNT_VALUE)
> - || PageBalloon(page));
> + return (test_bit(PG_movable, &(page)->flags) &&
> + atomic_read(&page->_mapcount) == PAGE_MOVABLE_MAPCOUNT_VALUE);
> }
>
> /* Caller should hold a PG_lock */
> @@ -645,6 +626,35 @@ static inline void __ClearPageMovable(struct page *page)
>
> PAGEFLAG(Isolated, isolated, PF_ANY);
>
> +static inline int PageBalloon(struct page *page)
> +{
> + return atomic_read(&page->_mapcount) == PAGE_BALLOON_MAPCOUNT_VALUE
> + && PagePrivate2(page);
> +}
Hmm so you are now using PG_private_2 flag here, but it's not
documented. Also the only caller of PageBalloon() seems to be
stable_page_flags(). Which will now report all movable pages with
PG_private_2 as KPF_BALOON. Seems like an overkill and also not
reliable. Could it test e.g. page->mapping instead?
Or maybe if we manage to get rid of PAGE_MOVABLE_MAPCOUNT_VALUE, we can
keep PAGE_BALLOON_MAPCOUNT_VALUE to simply distinguish balloon pages for
stable_page_flags().
> @@ -1033,7 +1019,7 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
> out:
> /* If migration is successful, move newpage to right list */
> if (rc == MIGRATEPAGE_SUCCESS) {
> - if (unlikely(__is_movable_balloon_page(newpage)))
> + if (unlikely(PageMovable(newpage)))
> put_page(newpage);
> else
> putback_lru_page(newpage);
Hmm shouldn't the condition have been changed to
if (unlikely(__is_movable_balloon_page(newpage)) || PageMovable(newpage)
by patch 02/16? And this patch should be just removing the
balloon-specific check? Otherwise it seems like between patches 02 and
04, other kinds of PageMovable pages were unnecessarily/wrongly routed
through putback_lru_page()?
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index d82196244340..c7696a2e11c7 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -1254,7 +1254,7 @@ unsigned long reclaim_clean_pages_from_list(struct zone *zone,
>
> list_for_each_entry_safe(page, next, page_list, lru) {
> if (page_is_file_cache(page) && !PageDirty(page) &&
> - !isolated_balloon_page(page)) {
> + !PageIsolated(page)) {
> ClearPageActive(page);
> list_move(&page->lru, &clean_pages);
> }
This looks like the same comment as above at first glance. But looking
closer, it's even weirder. isolated_balloon_page() was simply
PageBalloon() after d6d86c0a7f8dd... weird already. You replace it with
check for !PageIsolated() which looks like a more correct check, so ok.
Except the potential false positive with PG_owner_priv_1.
Thanks.
next prev parent reply other threads:[~2016-04-05 12:03 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-30 7:11 [PATCH v3 00/16] Support non-lru page migration Minchan Kim
2016-03-30 7:12 ` [PATCH v3 01/16] mm: use put_page to free page instead of putback_lru_page Minchan Kim
2016-04-01 12:58 ` Vlastimil Babka
2016-04-04 1:39 ` Minchan Kim
2016-04-04 4:45 ` Naoya Horiguchi
2016-04-04 14:46 ` Vlastimil Babka
2016-04-05 1:54 ` Naoya Horiguchi
2016-04-05 8:20 ` Vlastimil Babka
2016-04-06 0:54 ` Naoya Horiguchi
2016-04-06 7:57 ` Vlastimil Babka
2016-04-04 5:53 ` Balbir Singh
2016-04-04 6:01 ` Minchan Kim
2016-04-05 3:10 ` Balbir Singh
2016-03-30 7:12 ` [PATCH v3 02/16] mm/compaction: support non-lru movable page migration Minchan Kim
2016-04-01 21:29 ` Vlastimil Babka
2016-04-04 5:12 ` Minchan Kim
2016-04-04 13:24 ` Vlastimil Babka
2016-04-07 2:35 ` Minchan Kim
2016-04-12 8:00 ` Chulmin Kim
2016-04-12 14:25 ` Minchan Kim
2016-03-30 7:12 ` [PATCH v3 03/16] mm: add non-lru movable page support document Minchan Kim
2016-04-01 14:38 ` Vlastimil Babka
2016-04-04 2:25 ` Minchan Kim
2016-04-04 13:09 ` Vlastimil Babka
2016-04-07 2:27 ` Minchan Kim
2016-03-30 7:12 ` [PATCH v3 04/16] mm/balloon: use general movable page feature into balloon Minchan Kim
2016-04-05 12:03 ` Vlastimil Babka [this message]
2016-04-11 4:29 ` Minchan Kim
2016-03-30 7:12 ` [PATCH v3 05/16] zsmalloc: keep max_object in size_class Minchan Kim
2016-04-17 15:08 ` Sergey Senozhatsky
2016-03-30 7:12 ` [PATCH v3 06/16] zsmalloc: squeeze inuse into page->mapping Minchan Kim
2016-04-17 15:08 ` Sergey Senozhatsky
2016-04-19 7:40 ` Minchan Kim
2016-03-30 7:12 ` [PATCH v3 07/16] zsmalloc: remove page_mapcount_reset Minchan Kim
2016-04-17 15:11 ` Sergey Senozhatsky
2016-03-30 7:12 ` [PATCH v3 08/16] zsmalloc: squeeze freelist into page->mapping Minchan Kim
2016-04-17 15:56 ` Sergey Senozhatsky
2016-04-19 7:42 ` Minchan Kim
2016-03-30 7:12 ` [PATCH v3 09/16] zsmalloc: move struct zs_meta from mapping to freelist Minchan Kim
2016-04-17 15:22 ` Sergey Senozhatsky
2016-03-30 7:12 ` [PATCH v3 10/16] zsmalloc: factor page chain functionality out Minchan Kim
2016-04-18 0:33 ` Sergey Senozhatsky
2016-04-19 7:46 ` Minchan Kim
2016-03-30 7:12 ` [PATCH v3 11/16] zsmalloc: separate free_zspage from putback_zspage Minchan Kim
2016-04-18 1:04 ` Sergey Senozhatsky
2016-04-19 7:51 ` Minchan Kim
2016-04-19 7:53 ` Sergey Senozhatsky
2016-03-30 7:12 ` [PATCH v3 12/16] zsmalloc: zs_compact refactoring Minchan Kim
2016-04-04 8:04 ` Chulmin Kim
2016-04-04 9:01 ` Minchan Kim
2016-03-30 7:12 ` [PATCH v3 13/16] zsmalloc: migrate head page of zspage Minchan Kim
2016-04-06 13:01 ` Chulmin Kim
2016-04-07 0:34 ` Chulmin Kim
2016-04-07 0:43 ` Minchan Kim
2016-04-19 6:08 ` Chulmin Kim
2016-04-19 6:15 ` Minchan Kim
2016-03-30 7:12 ` [PATCH v3 14/16] zsmalloc: use single linked list for page chain Minchan Kim
2016-03-30 7:12 ` [PATCH v3 15/16] zsmalloc: migrate tail pages in zspage Minchan Kim
2016-03-30 7:12 ` [PATCH v3 16/16] zram: use __GFP_MOVABLE for memory allocation Minchan Kim
2016-03-30 23:11 ` [PATCH v3 00/16] Support non-lru page migration Andrew Morton
2016-03-31 0:29 ` Sergey Senozhatsky
2016-03-31 0:57 ` Minchan Kim
2016-03-31 0:57 ` Minchan Kim
2016-04-04 13:17 ` John Einar Reitan
2016-04-11 4:35 ` Minchan Kim
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