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[PATCH v2 7/7] mm/page_alloc: introduce post allocation processing on page allocator

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  [PATCH v2 7/7] mm/page_alloc: introduce post allocation processing on page allocator js1304@gmail.com - 2016-05-26 04:40 +0200

#1407350 — [PATCH v2 7/7] mm/page_alloc: introduce post allocation processing on page allocator

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

This patch is motivated from Hugh and Vlastimil's concern [1].

There are two ways to get freepage from the allocator. One is using
normal memory allocation API and the other is __isolate_free_page() which
is internally used for compaction and pageblock isolation. Later usage is
rather tricky since it doesn't do whole post allocation processing
done by normal API.

One problematic thing I already know is that poisoned page would not be
checked if it is allocated by __isolate_free_page(). Perhaps, there would
be more.

We could add more debug logic for allocated page in the future and this
separation would cause more problem. I'd like to fix this situation
at this time. Solution is simple. This patch commonize some logic
for newly allocated page and uses it on all sites. This will solve
the problem.

[1] http://marc.info/?i=alpine.LSU.2.11.1604270029350.7066%40eggly.anvils%3E

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
---
 mm/compaction.c     |  8 +-------
 mm/internal.h       |  2 ++
 mm/page_alloc.c     | 22 +++++++++++++---------
 mm/page_isolation.c |  4 +---
 4 files changed, 17 insertions(+), 19 deletions(-)

diff --git a/mm/compaction.c b/mm/compaction.c
index 6043ef8..e15d350 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -75,14 +75,8 @@ static void map_pages(struct list_head *list)
 
 		order = page_private(page);
 		nr_pages = 1 << order;
-		set_page_private(page, 0);
-		set_page_refcounted(page);
 
-		arch_alloc_page(page, order);
-		kernel_map_pages(page, nr_pages, 1);
-		kasan_alloc_pages(page, order);
-
-		set_page_owner(page, order, __GFP_MOVABLE);
+		post_alloc_hook(page, order, __GFP_MOVABLE);
 		if (order)
 			split_page(page, order);
 
diff --git a/mm/internal.h b/mm/internal.h
index b6ead95..420bbe3 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -153,6 +153,8 @@ extern int __isolate_free_page(struct page *page, unsigned int order);
 extern void __free_pages_bootmem(struct page *page, unsigned long pfn,
 					unsigned int order);
 extern void prep_compound_page(struct page *page, unsigned int order);
+extern void post_alloc_hook(struct page *page, unsigned int order,
+					gfp_t gfp_flags);
 extern int user_min_free_kbytes;
 
 #if defined CONFIG_COMPACTION || defined CONFIG_CMA
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 616ada9..baa5999 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1722,6 +1722,18 @@ static bool check_new_pages(struct page *page, unsigned int order)
 	return false;
 }
 
+void post_alloc_hook(struct page *page, unsigned int order, gfp_t gfp_flags)
+{
+	set_page_private(page, 0);
+	set_page_refcounted(page);
+
+	arch_alloc_page(page, order);
+	kernel_map_pages(page, 1 << order, 1);
+	kernel_poison_pages(page, 1 << order, 1);
+	kasan_alloc_pages(page, order);
+	set_page_owner(page, order, gfp_flags);
+}
+
 static void prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags,
 							unsigned int alloc_flags)
 {
@@ -1734,13 +1746,7 @@ static void prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags
 			poisoned &= page_is_poisoned(p);
 	}
 
-	set_page_private(page, 0);
-	set_page_refcounted(page);
-
-	arch_alloc_page(page, order);
-	kernel_map_pages(page, 1 << order, 1);
-	kernel_poison_pages(page, 1 << order, 1);
-	kasan_alloc_pages(page, order);
+	post_alloc_hook(page, order, gfp_flags);
 
 	if (!free_pages_prezeroed(poisoned) && (gfp_flags & __GFP_ZERO))
 		for (i = 0; i < (1 << order); i++)
@@ -1749,8 +1755,6 @@ static void prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags
 	if (order && (gfp_flags & __GFP_COMP))
 		prep_compound_page(page, order);
 
-	set_page_owner(page, order, gfp_flags);
-
 	/*
 	 * page is set pfmemalloc when ALLOC_NO_WATERMARKS was necessary to
 	 * allocate the page. The expectation is that the caller is taking
diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index 927f5ee..4639163 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -128,9 +128,7 @@ static void unset_migratetype_isolate(struct page *page, unsigned migratetype)
 out:
 	spin_unlock_irqrestore(&zone->lock, flags);
 	if (isolated_page) {
-		kernel_map_pages(page, (1 << order), 1);
-		set_page_refcounted(page);
-		set_page_owner(page, order, __GFP_MOVABLE);
+		post_alloc_hook(page, order, __GFP_MOVABLE);
 		__free_pages(isolated_page, order);
 	}
 }
-- 
1.9.1

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