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From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
To: linux-mm@kvack.org
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Hugh Dickins <hughd@google.com>,
	William Kucharski <william.kucharski@oracle.com>,
	Jani Nikula <jani.nikula@linux.intel.com>,
	Alexey Dobriyan <adobriyan@gmail.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Chris Wilson <chris@chris-wilson.co.uk>,
	Matthew Auld <matthew.auld@intel.com>,
	Huang Ying <ying.huang@intel.com>,
	intel-gfx@lists.freedesktop.org, cgroups@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH v2 1/8] mm: Factor find_get_incore_page out of mincore_page
Date: Thu, 10 Sep 2020 19:33:11 +0100
Message-ID: <20200910183318.20139-2-willy@infradead.org> (raw)
In-Reply-To: <20200910183318.20139-1-willy@infradead.org>

Provide this functionality from the swap cache.  It's useful for
more than just mincore().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 include/linux/swap.h |  7 +++++++
 mm/mincore.c         | 28 ++--------------------------
 mm/swap_state.c      | 32 ++++++++++++++++++++++++++++++++
 3 files changed, 41 insertions(+), 26 deletions(-)

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 661046994db4..df87de38dca5 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -427,6 +427,7 @@ extern void free_pages_and_swap_cache(struct page **, int);
 extern struct page *lookup_swap_cache(swp_entry_t entry,
 				      struct vm_area_struct *vma,
 				      unsigned long addr);
+struct page *find_get_incore_page(struct address_space *mapping, pgoff_t index);
 extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
 			struct vm_area_struct *vma, unsigned long addr,
 			bool do_poll);
@@ -569,6 +570,12 @@ static inline struct page *lookup_swap_cache(swp_entry_t swp,
 	return NULL;
 }
 
+static inline
+struct page *find_get_incore_page(struct address_space *mapping, pgoff_t index)
+{
+	return find_get_page(mapping, index);
+}
+
 static inline int add_to_swap(struct page *page)
 {
 	return 0;
diff --git a/mm/mincore.c b/mm/mincore.c
index 453ff112470f..02db1a834021 100644
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -48,7 +48,7 @@ static int mincore_hugetlb(pte_t *pte, unsigned long hmask, unsigned long addr,
  * and is up to date; i.e. that no page-in operation would be required
  * at this time if an application were to map and access this page.
  */
-static unsigned char mincore_page(struct address_space *mapping, pgoff_t pgoff)
+static unsigned char mincore_page(struct address_space *mapping, pgoff_t index)
 {
 	unsigned char present = 0;
 	struct page *page;
@@ -59,31 +59,7 @@ static unsigned char mincore_page(struct address_space *mapping, pgoff_t pgoff)
 	 * any other file mapping (ie. marked !present and faulted in with
 	 * tmpfs's .fault). So swapped out tmpfs mappings are tested here.
 	 */
-#ifdef CONFIG_SWAP
-	if (shmem_mapping(mapping)) {
-		page = find_get_entry(mapping, pgoff);
-		/*
-		 * shmem/tmpfs may return swap: account for swapcache
-		 * page too.
-		 */
-		if (xa_is_value(page)) {
-			swp_entry_t swp = radix_to_swp_entry(page);
-			struct swap_info_struct *si;
-
-			/* Prevent swap device to being swapoff under us */
-			si = get_swap_device(swp);
-			if (si) {
-				page = find_get_page(swap_address_space(swp),
-						     swp_offset(swp));
-				put_swap_device(si);
-			} else
-				page = NULL;
-		}
-	} else
-		page = find_get_page(mapping, pgoff);
-#else
-	page = find_get_page(mapping, pgoff);
-#endif
+	page = find_get_incore_page(mapping, index);
 	if (page) {
 		present = PageUptodate(page);
 		put_page(page);
diff --git a/mm/swap_state.c b/mm/swap_state.c
index c16eebb81d8b..c79e2242dd04 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -21,6 +21,7 @@
 #include <linux/vmalloc.h>
 #include <linux/swap_slots.h>
 #include <linux/huge_mm.h>
+#include <linux/shmem_fs.h>
 #include "internal.h"
 
 /*
@@ -414,6 +415,37 @@ struct page *lookup_swap_cache(swp_entry_t entry, struct vm_area_struct *vma,
 	return page;
 }
 
+/**
+ * find_get_incore_page - Find and get a page from the page or swap caches.
+ * @mapping: The address_space to search.
+ * @index: The page cache index.
+ *
+ * This differs from find_get_page() in that it will also look for the
+ * page in the swap cache.
+ *
+ * Return: The found page or %NULL.
+ */
+struct page *find_get_incore_page(struct address_space *mapping, pgoff_t index)
+{
+	swp_entry_t swp;
+	struct swap_info_struct *si;
+	struct page *page = find_get_entry(mapping, index);
+
+	if (!xa_is_value(page))
+		return page;
+	if (!shmem_mapping(mapping))
+		return NULL;
+
+	swp = radix_to_swp_entry(page);
+	/* Prevent swapoff from happening to us */
+	si = get_swap_device(swp);
+	if (!si)
+		return NULL;
+	page = find_get_page(swap_address_space(swp), swp_offset(swp));
+	put_swap_device(si);
+	return page;
+}
+
 struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
 			struct vm_area_struct *vma, unsigned long addr,
 			bool *new_page_allocated)
-- 
2.28.0



  reply index

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-10 18:33 [PATCH v2 0/8] Return head pages from find_*_entry Matthew Wilcox (Oracle)
2020-09-10 18:33 ` Matthew Wilcox (Oracle) [this message]
2020-09-10 18:33 ` [PATCH v2 2/8] mm: Use find_get_incore_page in memcontrol Matthew Wilcox (Oracle)
2020-09-10 18:33 ` [PATCH v2 3/8] mm: Optimise madvise WILLNEED Matthew Wilcox (Oracle)
2020-09-14 16:17   ` Qian Cai
2020-09-14 16:47     ` Qian Cai
2020-09-14 16:50     ` Matthew Wilcox
2020-09-14 19:44       ` Qian Cai
2020-09-10 18:33 ` [PATCH v2 4/8] proc: Optimise smaps for shmem entries Matthew Wilcox (Oracle)
2020-09-10 18:33 ` [PATCH v2 5/8] i915: Use find_lock_page instead of find_lock_entry Matthew Wilcox (Oracle)
2020-09-10 18:33 ` [PATCH v2 6/8] mm: Convert find_get_entry to return the head page Matthew Wilcox (Oracle)
2020-09-14  8:55   ` [mm] 2037ab69a5: BUG:KASAN:null-ptr-deref_in_t kernel test robot
2020-09-14 11:27     ` Matthew Wilcox
2020-09-10 18:33 ` [PATCH v2 7/8] mm/shmem: Return head page from find_lock_entry Matthew Wilcox (Oracle)
2020-09-12  3:20   ` Matthew Wilcox
2020-09-10 18:33 ` [PATCH v2 8/8] mm: Add find_lock_head Matthew Wilcox (Oracle)
2020-09-15  8:10 ` [PATCH v2 0/8] Return head pages from find_*_entry Hugh Dickins
2020-09-15 12:53   ` Naresh Kamboju
2020-09-15 13:08     ` Matthew Wilcox

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