From: Minchan Kim <minchan@xxxxxxxxxx>
Subject: zsmalloc: clean up many BUG_ON
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@xxxxxxxxxx>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/zsmalloc.c | 42 +++++++++++++++---------------------------
1 file changed, 15 insertions(+), 27 deletions(-)
diff -puN mm/zsmalloc.c~zsmalloc-clean-up-many-bug_on mm/zsmalloc.c
--- a/mm/zsmalloc.c~zsmalloc-clean-up-many-bug_on
+++ a/mm/zsmalloc.c
@@ -418,7 +418,7 @@ static void get_zspage_mapping(struct pa
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;
@@ -430,7 +430,7 @@ static void set_zspage_mapping(struct pa
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);
@@ -631,7 +631,8 @@ static enum fullness_group get_fullness_
{
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;
@@ -659,7 +660,7 @@ static void insert_zspage(struct page *f
{
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;
@@ -691,13 +692,13 @@ static void remove_zspage(struct page *f
{
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)
@@ -724,8 +725,6 @@ static enum fullness_group fix_fullness_
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)
@@ -811,7 +810,7 @@ static void *location_to_obj(struct page
unsigned long obj;
if (!page) {
- BUG_ON(obj_idx);
+ VM_BUG_ON(obj_idx);
return NULL;
}
@@ -844,7 +843,7 @@ static unsigned long obj_to_head(struct
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;
@@ -894,8 +893,8 @@ static void free_zspage(struct page *fir
{
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);
@@ -921,7 +920,8 @@ static void init_zspage(struct page *fir
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;
@@ -1238,7 +1238,7 @@ static bool can_merge(struct size_class
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;
}
@@ -1276,14 +1276,12 @@ void *zs_map_object(struct zs_pool *pool
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);
@@ -1327,8 +1325,6 @@ void zs_unmap_object(struct zs_pool *poo
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);
@@ -1448,8 +1444,6 @@ static void obj_free(struct zs_pool *poo
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);
@@ -1549,7 +1543,6 @@ static void zs_object_copy(unsigned long
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;
@@ -1559,7 +1552,6 @@ static void zs_object_copy(unsigned long
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;
@@ -1694,8 +1686,6 @@ static enum fullness_group putback_zspag
{
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);
@@ -1759,8 +1749,6 @@ static void __zs_compact(struct zs_pool
spin_lock(&class->lock);
while ((src_page = isolate_source_page(class))) {
- BUG_ON(!is_first_page(src_page));
-
if (!zs_can_compact(class))
break;
_
--
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