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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,
	jlayton@poochiereds.net, bfields@fieldses.org,
	Vlastimil Babka <vbabka@suse.cz>,
	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>,
	rknize@motorola.com, Rik van Riel <riel@redhat.com>,
	Gioh Kim <gurugio@hanmail.net>, Minchan Kim <minchan@kernel.org>
Subject: [PATCH v1 06/19] zsmalloc: clean up many BUG_ON
Date: Fri, 11 Mar 2016 16:30:10 +0900	[thread overview]
Message-ID: <1457681423-26664-7-git-send-email-minchan@kernel.org> (raw)
In-Reply-To: <1457681423-26664-1-git-send-email-minchan@kernel.org>

There are many BUG_ON in zsmalloc.c which is not recommened so
change them as alternatives.

Normal rule is as follows:

1. avoid BUG_ON if possible. Instead, use VM_BUG_ON or VM_BUG_ON_PAGE
2. use VM_BUG_ON_PAGE if we need to see struct page's fields
3. use those assertion in primitive functions so higher functions
can rely on the assertion in the primitive function.
4. Don't use assertion if following instruction can trigger Oops

Signed-off-by: Minchan Kim <minchan@kernel.org>
---
 mm/zsmalloc.c | 42 +++++++++++++++---------------------------
 1 file changed, 15 insertions(+), 27 deletions(-)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index bb29203ec6b3..3c82011cc405 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -419,7 +419,7 @@ static void get_zspage_mapping(struct page *first_page,
 				enum fullness_group *fullness)
 {
 	unsigned long m;
-	BUG_ON(!is_first_page(first_page));
+	VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
 
 	m = (unsigned long)first_page->mapping;
 	*fullness = m & FULLNESS_MASK;
@@ -431,7 +431,7 @@ static void set_zspage_mapping(struct page *first_page,
 				enum fullness_group fullness)
 {
 	unsigned long m;
-	BUG_ON(!is_first_page(first_page));
+	VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
 
 	m = ((class_idx & CLASS_IDX_MASK) << FULLNESS_BITS) |
 			(fullness & FULLNESS_MASK);
@@ -626,7 +626,8 @@ static enum fullness_group get_fullness_group(struct page *first_page)
 {
 	int inuse, max_objects;
 	enum fullness_group fg;
-	BUG_ON(!is_first_page(first_page));
+
+	VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
 
 	inuse = first_page->inuse;
 	max_objects = first_page->objects;
@@ -654,7 +655,7 @@ static void insert_zspage(struct page *first_page, struct size_class *class,
 {
 	struct page **head;
 
-	BUG_ON(!is_first_page(first_page));
+	VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
 
 	if (fullness >= _ZS_NR_FULLNESS_GROUPS)
 		return;
@@ -686,13 +687,13 @@ static void remove_zspage(struct page *first_page, struct size_class *class,
 {
 	struct page **head;
 
-	BUG_ON(!is_first_page(first_page));
+	VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
 
 	if (fullness >= _ZS_NR_FULLNESS_GROUPS)
 		return;
 
 	head = &class->fullness_list[fullness];
-	BUG_ON(!*head);
+	VM_BUG_ON_PAGE(!*head, first_page);
 	if (list_empty(&(*head)->lru))
 		*head = NULL;
 	else if (*head == first_page)
@@ -719,8 +720,6 @@ static enum fullness_group fix_fullness_group(struct size_class *class,
 	int class_idx;
 	enum fullness_group currfg, newfg;
 
-	BUG_ON(!is_first_page(first_page));
-
 	get_zspage_mapping(first_page, &class_idx, &currfg);
 	newfg = get_fullness_group(first_page);
 	if (newfg == currfg)
@@ -806,7 +805,7 @@ static void *location_to_obj(struct page *page, unsigned long obj_idx)
 	unsigned long obj;
 
 	if (!page) {
-		BUG_ON(obj_idx);
+		VM_BUG_ON(obj_idx);
 		return NULL;
 	}
 
@@ -839,7 +838,7 @@ static unsigned long obj_to_head(struct size_class *class, struct page *page,
 			void *obj)
 {
 	if (class->huge) {
-		VM_BUG_ON(!is_first_page(page));
+		VM_BUG_ON_PAGE(!is_first_page(page), page);
 		return page_private(page);
 	} else
 		return *(unsigned long *)obj;
@@ -889,8 +888,8 @@ static void free_zspage(struct page *first_page)
 {
 	struct page *nextp, *tmp, *head_extra;
 
-	BUG_ON(!is_first_page(first_page));
-	BUG_ON(first_page->inuse);
+	VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
+	VM_BUG_ON_PAGE(first_page->inuse, first_page);
 
 	head_extra = (struct page *)page_private(first_page);
 
@@ -916,7 +915,8 @@ static void init_zspage(struct page *first_page, struct size_class *class)
 	unsigned long off = 0;
 	struct page *page = first_page;
 
-	BUG_ON(!is_first_page(first_page));
+	VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
+
 	while (page) {
 		struct page *next_page;
 		struct link_free *link;
@@ -1235,7 +1235,7 @@ static bool can_merge(struct size_class *prev, int size, int pages_per_zspage)
 
 static bool zspage_full(struct page *first_page)
 {
-	BUG_ON(!is_first_page(first_page));
+	VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
 
 	return first_page->inuse == first_page->objects;
 }
@@ -1273,14 +1273,12 @@ void *zs_map_object(struct zs_pool *pool, unsigned long handle,
 	struct page *pages[2];
 	void *ret;
 
-	BUG_ON(!handle);
-
 	/*
 	 * Because we use per-cpu mapping areas shared among the
 	 * pools/users, we can't allow mapping in interrupt context
 	 * because it can corrupt another users mappings.
 	 */
-	BUG_ON(in_interrupt());
+	WARN_ON_ONCE(in_interrupt());
 
 	/* From now on, migration cannot move the object */
 	pin_tag(handle);
@@ -1324,8 +1322,6 @@ void zs_unmap_object(struct zs_pool *pool, unsigned long handle)
 	struct size_class *class;
 	struct mapping_area *area;
 
-	BUG_ON(!handle);
-
 	obj = handle_to_obj(handle);
 	obj_to_location(obj, &page, &obj_idx);
 	get_zspage_mapping(get_first_page(page), &class_idx, &fg);
@@ -1445,8 +1441,6 @@ static void obj_free(struct zs_pool *pool, struct size_class *class,
 	unsigned long f_objidx, f_offset;
 	void *vaddr;
 
-	BUG_ON(!obj);
-
 	obj &= ~OBJ_ALLOCATED_TAG;
 	obj_to_location(obj, &f_page, &f_objidx);
 	first_page = get_first_page(f_page);
@@ -1546,7 +1540,6 @@ static void zs_object_copy(unsigned long dst, unsigned long src,
 			kunmap_atomic(d_addr);
 			kunmap_atomic(s_addr);
 			s_page = get_next_page(s_page);
-			BUG_ON(!s_page);
 			s_addr = kmap_atomic(s_page);
 			d_addr = kmap_atomic(d_page);
 			s_size = class->size - written;
@@ -1556,7 +1549,6 @@ static void zs_object_copy(unsigned long dst, unsigned long src,
 		if (d_off >= PAGE_SIZE) {
 			kunmap_atomic(d_addr);
 			d_page = get_next_page(d_page);
-			BUG_ON(!d_page);
 			d_addr = kmap_atomic(d_page);
 			d_size = class->size - written;
 			d_off = 0;
@@ -1691,8 +1683,6 @@ static enum fullness_group putback_zspage(struct zs_pool *pool,
 {
 	enum fullness_group fullness;
 
-	BUG_ON(!is_first_page(first_page));
-
 	fullness = get_fullness_group(first_page);
 	insert_zspage(first_page, class, fullness);
 	set_zspage_mapping(first_page, class->index, fullness);
@@ -1753,8 +1743,6 @@ static void __zs_compact(struct zs_pool *pool, struct size_class *class)
 	spin_lock(&class->lock);
 	while ((src_page = isolate_source_page(class))) {
 
-		BUG_ON(!is_first_page(src_page));
-
 		if (!zs_can_compact(class))
 			break;
 
-- 
1.9.1

  parent reply	other threads:[~2016-03-11  7:30 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-11  7:30 [PATCH v1 00/19] Support non-lru page migration Minchan Kim
2016-03-11  7:30 ` [PATCH v1 01/19] mm: use put_page to free page instead of putback_lru_page Minchan Kim
2016-03-14  8:48   ` Vlastimil Babka
2016-03-15  1:16     ` Minchan Kim
2016-03-15 19:06       ` Vlastimil Babka
2016-03-11  7:30 ` [PATCH v1 02/19] mm/compaction: support non-lru movable page migration Minchan Kim
2016-03-11  8:11   ` kbuild test robot
2016-03-11  8:35     ` Minchan Kim
2016-03-11  7:30 ` [PATCH v1 03/19] fs/anon_inodes: new interface to create new inode Minchan Kim
2016-03-11  8:05   ` Al Viro
2016-03-11 14:24     ` Gioh Kim
2016-03-11  7:30 ` [PATCH v1 04/19] mm/balloon: use general movable page feature into balloon Minchan Kim
2016-03-11  7:30 ` [PATCH v1 05/19] zsmalloc: use first_page rather than page Minchan Kim
2016-03-15  6:19   ` Sergey Senozhatsky
2016-03-11  7:30 ` Minchan Kim [this message]
2016-03-15  6:19   ` [PATCH v1 06/19] zsmalloc: clean up many BUG_ON Sergey Senozhatsky
2016-03-11  7:30 ` [PATCH v1 07/19] zsmalloc: reordering function parameter Minchan Kim
2016-03-15  6:20   ` Sergey Senozhatsky
2016-03-11  7:30 ` [PATCH v1 08/19] zsmalloc: remove unused pool param in obj_free Minchan Kim
2016-03-15  6:21   ` Sergey Senozhatsky
2016-03-11  7:30 ` [PATCH v1 09/19] zsmalloc: keep max_object in size_class Minchan Kim
2016-03-12  1:44   ` xuyiping
2016-03-14  4:55     ` Minchan Kim
2016-03-15  6:28   ` Sergey Senozhatsky
2016-03-15  6:41     ` Minchan Kim
2016-03-11  7:30 ` [PATCH v1 10/19] zsmalloc: squeeze inuse into page->mapping Minchan Kim
2016-03-11  7:30 ` [PATCH v1 11/19] zsmalloc: squeeze freelist " Minchan Kim
2016-03-15  6:40   ` Sergey Senozhatsky
2016-03-15  6:51     ` Minchan Kim
2016-03-17 12:09       ` YiPing Xu
2016-03-17 22:17         ` Minchan Kim
2016-03-11  7:30 ` [PATCH v1 12/19] zsmalloc: move struct zs_meta from mapping to freelist Minchan Kim
2016-03-11  7:30 ` [PATCH v1 13/19] zsmalloc: factor page chain functionality out Minchan Kim
2016-03-12  3:09   ` xuyiping
2016-03-14  4:58     ` Minchan Kim
2016-03-11  7:30 ` [PATCH v1 14/19] zsmalloc: separate free_zspage from putback_zspage Minchan Kim
2016-03-11  7:30 ` [PATCH v1 15/19] zsmalloc: zs_compact refactoring Minchan Kim
2016-03-11  7:30 ` [PATCH v1 16/19] zsmalloc: migrate head page of zspage Minchan Kim
2016-03-11  7:30 ` [PATCH v1 17/19] zsmalloc: use single linked list for page chain Minchan Kim
2016-03-11  7:30 ` [PATCH v1 18/19] zsmalloc: migrate tail pages in zspage Minchan Kim
2016-03-11  7:30 ` [PATCH v1 19/19] zram: use __GFP_MOVABLE for memory allocation Minchan Kim
2016-03-15  6:56   ` Sergey Senozhatsky

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