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>,
Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Subject: Re: [PATCH v3 01/16] mm: use put_page to free page instead of putback_lru_page
Date: Fri, 1 Apr 2016 14:58:21 +0200 [thread overview]
Message-ID: <56FE706D.7080507@suse.cz> (raw)
In-Reply-To: <1459321935-3655-2-git-send-email-minchan@kernel.org>
On 03/30/2016 09:12 AM, Minchan Kim wrote:
> Procedure of page migration is as follows:
>
> First of all, it should isolate a page from LRU and try to
> migrate the page. If it is successful, it releases the page
> for freeing. Otherwise, it should put the page back to LRU
> list.
>
> For LRU pages, we have used putback_lru_page for both freeing
> and putback to LRU list. It's okay because put_page is aware of
> LRU list so if it releases last refcount of the page, it removes
> the page from LRU list. However, It makes unnecessary operations
> (e.g., lru_cache_add, pagevec and flags operations. It would be
> not significant but no worth to do) and harder to support new
> non-lru page migration because put_page isn't aware of non-lru
> page's data structure.
>
> To solve the problem, we can add new hook in put_page with
> PageMovable flags check but it can increase overhead in
> hot path and needs new locking scheme to stabilize the flag check
> with put_page.
>
> So, this patch cleans it up to divide two semantic(ie, put and putback).
> If migration is successful, use put_page instead of putback_lru_page and
> use putback_lru_page only on failure. That makes code more readable
> and doesn't add overhead in put_page.
>
> Comment from Vlastimil
> "Yeah, and compaction (perhaps also other migration users) has to drain
> the lru pvec... Getting rid of this stuff is worth even by itself."
>
> Cc: Mel Gorman <mgorman@suse.de>
> Cc: Hugh Dickins <hughd@google.com>
> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> Acked-by: Vlastimil Babka <vbabka@suse.cz>
> Signed-off-by: Minchan Kim <minchan@kernel.org>
[...]
> @@ -974,28 +986,28 @@ static ICE_noinline int unmap_and_move(new_page_t get_new_page,
> list_del(&page->lru);
> dec_zone_page_state(page, NR_ISOLATED_ANON +
> page_is_file_cache(page));
> - /* Soft-offlined page shouldn't go through lru cache list */
> + }
> +
> + /*
> + * If migration is successful, drop the reference grabbed during
> + * isolation. Otherwise, restore the page to LRU list unless we
> + * want to retry.
> + */
> + if (rc == MIGRATEPAGE_SUCCESS) {
> + put_page(page);
> if (reason == MR_MEMORY_FAILURE) {
> - put_page(page);
> if (!test_set_page_hwpoison(page))
> num_poisoned_pages_inc();
> - } else
> + }
Hmm, I didn't notice it previously, or it's due to rebasing, but it seems that
you restricted the memory failure handling (i.e. setting hwpoison) to
MIGRATE_SUCCESS, while previously it was done for all non-EAGAIN results. I
think that goes against the intention of hwpoison, which is IIRC to catch and
kill the poor process that still uses the page?
Also (but not your fault) the put_page() preceding test_set_page_hwpoison(page))
IMHO deserves a comment saying which pin we are releasing and which one we still
have (hopefully? if I read description of da1b13ccfbebe right) otherwise it
looks like doing something with a page that we just potentially freed.
> + } else {
> + if (rc != -EAGAIN)
> putback_lru_page(page);
> + if (put_new_page)
> + put_new_page(newpage, private);
> + else
> + put_page(newpage);
> }
>
> - /*
> - * If migration was not successful and there's a freeing callback, use
> - * it. Otherwise, putback_lru_page() will drop the reference grabbed
> - * during isolation.
> - */
> - if (put_new_page)
> - put_new_page(newpage, private);
> - else if (unlikely(__is_movable_balloon_page(newpage))) {
> - /* drop our reference, page already in the balloon */
> - put_page(newpage);
> - } else
> - putback_lru_page(newpage);
> -
> if (result) {
> if (rc)
> *result = rc;
>
next prev parent reply other threads:[~2016-04-01 12:58 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 [this message]
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
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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