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From: Minchan Kim <minchan@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Minchan Kim <minchan@kernel.org>, Rik van Riel <riel@redhat.com>,
	Mel Gorman <mgorman@suse.de>, Hugh Dickins <hughd@google.com>,
	Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
	Vlastimil Babka <vbabka@suse.cz>
Subject: [PATCH v6 01/12] mm: use put_page to free page instead of putback_lru_page
Date: Fri, 20 May 2016 23:23:34 +0900	[thread overview]
Message-ID: <1463754225-31311-2-git-send-email-minchan@kernel.org> (raw)
In-Reply-To: <1463754225-31311-1-git-send-email-minchan@kernel.org>

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: Rik van Riel <riel@redhat.com>
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>
---
 mm/migrate.c | 64 +++++++++++++++++++++++++++++++++++++-----------------------
 1 file changed, 40 insertions(+), 24 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index 9baf41c877ff..2666f28b5236 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -913,6 +913,19 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
 		put_anon_vma(anon_vma);
 	unlock_page(page);
 out:
+	/*
+	 * If migration is successful, decrease refcount of the newpage
+	 * which will not free the page because new page owner increased
+	 * refcounter. As well, if it is LRU page, add the page to LRU
+	 * list in here.
+	 */
+	if (rc == MIGRATEPAGE_SUCCESS) {
+		if (unlikely(__is_movable_balloon_page(newpage)))
+			put_page(newpage);
+		else
+			putback_lru_page(newpage);
+	}
+
 	return rc;
 }
 
@@ -946,6 +959,12 @@ static ICE_noinline int unmap_and_move(new_page_t get_new_page,
 
 	if (page_count(page) == 1) {
 		/* page was freed from under us. So we are done. */
+		ClearPageActive(page);
+		ClearPageUnevictable(page);
+		if (put_new_page)
+			put_new_page(newpage, private);
+		else
+			put_page(newpage);
 		goto out;
 	}
 
@@ -958,10 +977,8 @@ static ICE_noinline int unmap_and_move(new_page_t get_new_page,
 	}
 
 	rc = __unmap_and_move(page, newpage, force, mode);
-	if (rc == MIGRATEPAGE_SUCCESS) {
-		put_new_page = NULL;
+	if (rc == MIGRATEPAGE_SUCCESS)
 		set_page_owner_migrate_reason(newpage, reason);
-	}
 
 out:
 	if (rc != -EAGAIN) {
@@ -974,34 +991,33 @@ 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 (reason == MR_MEMORY_FAILURE && rc == MIGRATEPAGE_SUCCESS) {
+	}
+
+	/*
+	 * If migration is successful, releases reference grabbed during
+	 * isolation. Otherwise, restore the page to right list unless
+	 * we want to retry.
+	 */
+	if (rc == MIGRATEPAGE_SUCCESS) {
+		put_page(page);
+		if (reason == MR_MEMORY_FAILURE) {
 			/*
-			 * With this release, we free successfully migrated
-			 * page and set PG_HWPoison on just freed page
-			 * intentionally. Although it's rather weird, it's how
-			 * HWPoison flag works at the moment.
+			 * Set PG_HWPoison on just freed page
+			 * intentionally. Although it's rather weird,
+			 * it's how HWPoison flag works at the moment.
 			 */
-			put_page(page);
 			if (!test_set_page_hwpoison(page))
 				num_poisoned_pages_inc();
-		} else
+		}
+	} 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;
-- 
1.9.1

  reply	other threads:[~2016-05-20 14:24 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 ` Minchan Kim [this message]
2016-05-20 14:23 ` [PATCH v6 02/12] mm: migrate: support non-lru movable " 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
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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