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From: js1304@gmail.com
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Johannes Weiner <hannes@cmpxchg.org>,
	Michal Hocko <mhocko@kernel.org>, Hugh Dickins <hughd@google.com>,
	Minchan Kim <minchan@kernel.org>,
	Vlastimil Babka <vbabka@suse.cz>,
	Mel Gorman <mgorman@techsingularity.net>,
	kernel-team@lge.com, Joonsoo Kim <iamjoonsoo.kim@lge.com>
Subject: [PATCH v5 04/10] mm/swapcache: support to handle the exceptional entries in swapcache
Date: Fri,  3 Apr 2020 14:40:42 +0900	[thread overview]
Message-ID: <1585892447-32059-5-git-send-email-iamjoonsoo.kim@lge.com> (raw)
In-Reply-To: <1585892447-32059-1-git-send-email-iamjoonsoo.kim@lge.com>

From: Joonsoo Kim <iamjoonsoo.kim@lge.com>

Swapcache doesn't handle the exceptional entries since there is no case
using it. In the following patch, workingset detection for anonymous
page will be implemented and it stores the shadow entries as exceptional
entries into the swapcache. So, we need to handle the exceptional entries
and this patch implements it.

Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
---
 include/linux/swap.h | 10 ++++++----
 mm/shmem.c           |  3 ++-
 mm/swap_state.c      | 26 ++++++++++++++++++++------
 mm/vmscan.c          |  2 +-
 4 files changed, 29 insertions(+), 12 deletions(-)

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 954e13e..273de48 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -408,9 +408,11 @@ extern struct address_space *swapper_spaces[];
 extern unsigned long total_swapcache_pages(void);
 extern void show_swap_cache_info(void);
 extern int add_to_swap(struct page *page);
-extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
+extern int add_to_swap_cache(struct page *page, swp_entry_t entry,
+			gfp_t gfp, void **shadowp);
 extern int __add_to_swap_cache(struct page *page, swp_entry_t entry);
-extern void __delete_from_swap_cache(struct page *, swp_entry_t entry);
+extern void __delete_from_swap_cache(struct page *page,
+			swp_entry_t entry, void *shadow);
 extern void delete_from_swap_cache(struct page *);
 extern void free_page_and_swap_cache(struct page *);
 extern void free_pages_and_swap_cache(struct page **, int);
@@ -565,13 +567,13 @@ static inline int add_to_swap(struct page *page)
 }
 
 static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
-							gfp_t gfp_mask)
+					gfp_t gfp_mask, void **shadowp)
 {
 	return -1;
 }
 
 static inline void __delete_from_swap_cache(struct page *page,
-							swp_entry_t entry)
+					swp_entry_t entry, void *shadow)
 {
 }
 
diff --git a/mm/shmem.c b/mm/shmem.c
index aad3ba7..9e34b4e 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1370,7 +1370,8 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc)
 		list_add(&info->swaplist, &shmem_swaplist);
 
 	if (add_to_swap_cache(page, swap,
-			__GFP_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN) == 0) {
+			__GFP_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN,
+			NULL) == 0) {
 		spin_lock_irq(&info->lock);
 		shmem_recalc_inode(inode);
 		info->swapped++;
diff --git a/mm/swap_state.c b/mm/swap_state.c
index 8e7ce9a..f06af84 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -111,12 +111,15 @@ void show_swap_cache_info(void)
  * add_to_swap_cache resembles add_to_page_cache_locked on swapper_space,
  * but sets SwapCache flag and private instead of mapping and index.
  */
-int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp)
+int add_to_swap_cache(struct page *page, swp_entry_t entry,
+			gfp_t gfp, void **shadowp)
 {
 	struct address_space *address_space = swap_address_space(entry);
 	pgoff_t idx = swp_offset(entry);
 	XA_STATE_ORDER(xas, &address_space->i_pages, idx, compound_order(page));
 	unsigned long i, nr = compound_nr(page);
+	unsigned long nrexceptional = 0;
+	void *old;
 
 	VM_BUG_ON_PAGE(!PageLocked(page), page);
 	VM_BUG_ON_PAGE(PageSwapCache(page), page);
@@ -132,10 +135,17 @@ int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp)
 			goto unlock;
 		for (i = 0; i < nr; i++) {
 			VM_BUG_ON_PAGE(xas.xa_index != idx + i, page);
+			old = xas_load(&xas);
+			if (xa_is_value(old)) {
+				nrexceptional++;
+				if (shadowp)
+					*shadowp = old;
+			}
 			set_page_private(page + i, entry.val + i);
 			xas_store(&xas, page);
 			xas_next(&xas);
 		}
+		address_space->nrexceptional -= nrexceptional;
 		address_space->nrpages += nr;
 		__mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, nr);
 		ADD_CACHE_INFO(add_total, nr);
@@ -155,7 +165,8 @@ int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp)
  * This must be called only on pages that have
  * been verified to be in the swap cache.
  */
-void __delete_from_swap_cache(struct page *page, swp_entry_t entry)
+void __delete_from_swap_cache(struct page *page,
+			swp_entry_t entry, void *shadow)
 {
 	struct address_space *address_space = swap_address_space(entry);
 	int i, nr = hpage_nr_pages(page);
@@ -167,12 +178,14 @@ void __delete_from_swap_cache(struct page *page, swp_entry_t entry)
 	VM_BUG_ON_PAGE(PageWriteback(page), page);
 
 	for (i = 0; i < nr; i++) {
-		void *entry = xas_store(&xas, NULL);
+		void *entry = xas_store(&xas, shadow);
 		VM_BUG_ON_PAGE(entry != page, entry);
 		set_page_private(page + i, 0);
 		xas_next(&xas);
 	}
 	ClearPageSwapCache(page);
+	if (shadow)
+		address_space->nrexceptional += nr;
 	address_space->nrpages -= nr;
 	__mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, -nr);
 	ADD_CACHE_INFO(del_total, nr);
@@ -209,7 +222,7 @@ int add_to_swap(struct page *page)
 	 * Add it to the swap cache.
 	 */
 	err = add_to_swap_cache(page, entry,
-			__GFP_HIGH|__GFP_NOMEMALLOC|__GFP_NOWARN);
+			__GFP_HIGH|__GFP_NOMEMALLOC|__GFP_NOWARN, NULL);
 	if (err)
 		/*
 		 * add_to_swap_cache() doesn't return -EEXIST, so we can safely
@@ -247,7 +260,7 @@ void delete_from_swap_cache(struct page *page)
 	struct address_space *address_space = swap_address_space(entry);
 
 	xa_lock_irq(&address_space->i_pages);
-	__delete_from_swap_cache(page, entry);
+	__delete_from_swap_cache(page, entry, NULL);
 	xa_unlock_irq(&address_space->i_pages);
 
 	put_swap_page(page, entry);
@@ -418,7 +431,8 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
 		/* May fail (-ENOMEM) if XArray node allocation failed. */
 		__SetPageLocked(new_page);
 		__SetPageSwapBacked(new_page);
-		err = add_to_swap_cache(new_page, entry, gfp_mask & GFP_KERNEL);
+		err = add_to_swap_cache(new_page, entry,
+				gfp_mask & GFP_KERNEL, NULL);
 		if (likely(!err)) {
 			/* Initiate read into locked page */
 			SetPageWorkingset(new_page);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 7196ccc..d46e3e5 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -895,7 +895,7 @@ static int __remove_mapping(struct address_space *mapping, struct page *page,
 	if (PageSwapCache(page)) {
 		swp_entry_t swap = { .val = page_private(page) };
 		mem_cgroup_swapout(page, swap);
-		__delete_from_swap_cache(page, swap);
+		__delete_from_swap_cache(page, swap, NULL);
 		xa_unlock_irqrestore(&mapping->i_pages, flags);
 		put_swap_page(page, swap);
 	} else {
-- 
2.7.4



  parent reply	other threads:[~2020-04-03  5:41 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-03  5:40 [PATCH v5 00/10] workingset protection/detection on the anonymous LRU list js1304
2020-04-03  5:40 ` [PATCH v5 01/10] mm/vmscan: make active/inactive ratio as 1:1 for anon lru js1304
2020-04-03  5:40 ` [PATCH v5 02/10] mm/vmscan: protect the workingset on anonymous LRU js1304
2020-04-03  5:40 ` [PATCH v5 03/10] mm/workingset: extend the workingset detection for anon LRU js1304
2020-04-03  5:40 ` js1304 [this message]
2020-04-03  5:40 ` [PATCH v5 05/10] mm/swap: charge the page when adding to the swap cache js1304
2020-04-03 18:29   ` Yang Shi
2020-04-06  1:03     ` Joonsoo Kim
2020-04-07  0:22       ` Yang Shi
2020-04-07  1:27         ` Joonsoo Kim
2020-04-16 16:11   ` Johannes Weiner
2020-04-17  1:38     ` Joonsoo Kim
2020-04-17  3:31       ` Johannes Weiner
2020-04-17  3:57         ` Joonsoo Kim
2020-04-03  5:40 ` [PATCH v5 06/10] mm/swap: implement workingset detection for anonymous LRU js1304
2020-04-03  5:40 ` [PATCH v5 07/10] mm/workingset: support to remember the previous owner of the page js1304
2020-04-03  5:40 ` [PATCH v5 08/10] mm/swap: do not readahead if the previous owner of the swap entry isn't me js1304
2020-04-03  5:40 ` [PATCH v5 09/10] mm/vmscan: restore active/inactive ratio for anonymous LRU js1304
2020-04-03  5:45 ` [PATCH v5 10/10] mm/swap: reinforce the reclaim_stat changed by anon LRU algorithm change js1304
2020-04-06  9:18 ` [PATCH v5 02/10] mm/vmscan: protect the workingset on anonymous LRU Hillf Danton
2020-04-07  0:40   ` Joonsoo Kim
2020-04-06 11:58 ` [PATCH v5 05/10] mm/swap: charge the page when adding to the swap cache Hillf Danton
2020-04-07  0:42   ` Joonsoo Kim
2020-04-07  2:21   ` Hillf Danton
2020-04-09  0:53     ` Joonsoo Kim
2020-04-08 16:55 ` [PATCH v5 00/10] workingset protection/detection on the anonymous LRU list Vlastimil Babka
2020-04-09  0:50   ` Joonsoo Kim
2020-06-03  3:57     ` Suren Baghdasaryan
2020-06-03  5:46       ` Joonsoo Kim

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