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Yang Shisfrothwell
Yang Shi
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sfrothwell
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mm: check the return value of lookup_page_ext for all call sites
Per the discussion with Joonsoo Kim [1], we need check the return value of lookup_page_ext() for all call sites since it might return NULL in some cases, although it is unlikely, i.e. memory hotplug. Tested with ltp with "page_owner=0". [1] http://lkml.kernel.org/r/20160519002809.GA10245@js1304-P5Q-DELUXE Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Yang Shi <[email protected]> Cc: Joonsoo Kim <[email protected]> Signed-off-by: Andrew Morton <[email protected]>
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5 files changed

+78
-8
lines changed

5 files changed

+78
-8
lines changed

‎include/linux/page_idle.h‎

Lines changed: 36 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -46,33 +46,62 @@ extern struct page_ext_operations page_idle_ops;
4646

4747
static inline bool page_is_young(struct page *page)
4848
{
49-
return test_bit(PAGE_EXT_YOUNG, &lookup_page_ext(page)->flags);
49+
struct page_ext *page_ext;
50+
page_ext = lookup_page_ext(page);
51+
if (unlikely(!page_ext)
52+
return false;
53+
54+
return test_bit(PAGE_EXT_YOUNG, &page_ext->flags);
5055
}
5156

5257
static inline void set_page_young(struct page *page)
5358
{
54-
set_bit(PAGE_EXT_YOUNG, &lookup_page_ext(page)->flags);
59+
struct page_ext *page_ext;
60+
page_ext = lookup_page_ext(page);
61+
if (unlikely(!page_ext)
62+
return;
63+
64+
set_bit(PAGE_EXT_YOUNG, &page_ext->flags);
5565
}
5666

5767
static inline bool test_and_clear_page_young(struct page *page)
5868
{
59-
return test_and_clear_bit(PAGE_EXT_YOUNG,
60-
&lookup_page_ext(page)->flags);
69+
struct page_ext *page_ext;
70+
page_ext = lookup_page_ext(page);
71+
if (unlikely(!page_ext)
72+
return false;
73+
74+
return test_and_clear_bit(PAGE_EXT_YOUNG, &page_ext->flags);
6175
}
6276

6377
static inline bool page_is_idle(struct page *page)
6478
{
65-
return test_bit(PAGE_EXT_IDLE, &lookup_page_ext(page)->flags);
79+
struct page_ext *page_ext;
80+
page_ext = lookup_page_ext(page);
81+
if (unlikely(!page_ext)
82+
return false;
83+
84+
return test_bit(PAGE_EXT_IDLE, &page_ext->flags);
6685
}
6786

6887
static inline void set_page_idle(struct page *page)
6988
{
70-
set_bit(PAGE_EXT_IDLE, &lookup_page_ext(page)->flags);
89+
struct page_ext *page_ext;
90+
page_ext = lookup_page_ext(page);
91+
if (unlikely(!page_ext)
92+
return;
93+
94+
set_bit(PAGE_EXT_IDLE, &page_ext->flags);
7195
}
7296

7397
static inline void clear_page_idle(struct page *page)
7498
{
75-
clear_bit(PAGE_EXT_IDLE, &lookup_page_ext(page)->flags);
99+
struct page_ext *page_ext;
100+
page_ext = lookup_page_ext(page);
101+
if (unlikely(!page_ext)
102+
return;
103+
104+
clear_bit(PAGE_EXT_IDLE, &page_ext->flags);
76105
}
77106
#endif /* CONFIG_64BIT */
78107

‎mm/page_alloc.c‎

Lines changed: 6 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -656,6 +656,9 @@ static inline void set_page_guard(struct zone *zone, struct page *page,
656656
return;
657657

658658
page_ext = lookup_page_ext(page);
659+
if (unlikely(!page_ext))
660+
return;
661+
659662
__set_bit(PAGE_EXT_DEBUG_GUARD, &page_ext->flags);
660663

661664
INIT_LIST_HEAD(&page->lru);
@@ -673,6 +676,9 @@ static inline void clear_page_guard(struct zone *zone, struct page *page,
673676
return;
674677

675678
page_ext = lookup_page_ext(page);
679+
if (unlikely(!page_ext))
680+
return;
681+
676682
__clear_bit(PAGE_EXT_DEBUG_GUARD, &page_ext->flags);
677683

678684
set_page_private(page, 0);

‎mm/page_owner.c‎

Lines changed: 27 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -55,13 +55,19 @@ void __reset_page_owner(struct page *page, unsigned int order)
5555

5656
for (i = 0; i < (1 << order); i++) {
5757
page_ext = lookup_page_ext(page + i);
58+
if (unlikely(!page_ext))
59+
continue;
5860
__clear_bit(PAGE_EXT_OWNER, &page_ext->flags);
5961
}
6062
}
6163

6264
void __set_page_owner(struct page *page, unsigned int order, gfp_t gfp_mask)
6365
{
6466
struct page_ext *page_ext = lookup_page_ext(page);
67+
68+
if (unlikely(!page_ext))
69+
return;
70+
6571
struct stack_trace trace = {
6672
.nr_entries = 0,
6773
.max_entries = ARRAY_SIZE(page_ext->trace_entries),
@@ -82,13 +88,21 @@ void __set_page_owner(struct page *page, unsigned int order, gfp_t gfp_mask)
8288
void __set_page_owner_migrate_reason(struct page *page, int reason)
8389
{
8490
struct page_ext *page_ext = lookup_page_ext(page);
91+
if (unlikely(!page_ext))
92+
return;
8593

8694
page_ext->last_migrate_reason = reason;
8795
}
8896

8997
gfp_t __get_page_owner_gfp(struct page *page)
9098
{
9199
struct page_ext *page_ext = lookup_page_ext(page);
100+
if (unlikely(!page_ext))
101+
/*
102+
* The caller just returns 0 if no valid gfp
103+
* So return 0 here too.
104+
*/
105+
return 0;
92106

93107
return page_ext->gfp_mask;
94108
}
@@ -97,6 +111,10 @@ void __copy_page_owner(struct page *oldpage, struct page *newpage)
97111
{
98112
struct page_ext *old_ext = lookup_page_ext(oldpage);
99113
struct page_ext *new_ext = lookup_page_ext(newpage);
114+
115+
if (unlikely(!old_ext || !new_ext))
116+
return;
117+
100118
int i;
101119

102120
new_ext->order = old_ext->order;
@@ -186,6 +204,11 @@ print_page_owner(char __user *buf, size_t count, unsigned long pfn,
186204
void __dump_page_owner(struct page *page)
187205
{
188206
struct page_ext *page_ext = lookup_page_ext(page);
207+
if (unlikely(!page_ext)) {
208+
pr_alert("There is not page extension available.\n");
209+
return;
210+
}
211+
189212
struct stack_trace trace = {
190213
.nr_entries = page_ext->nr_entries,
191214
.entries = &page_ext->trace_entries[0],
@@ -251,6 +274,8 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
251274
}
252275

253276
page_ext = lookup_page_ext(page);
277+
if (unlikely(!page_ext))
278+
continue;
254279

255280
/*
256281
* Some pages could be missed by concurrent allocation or free,
@@ -317,6 +342,8 @@ static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone)
317342
continue;
318343

319344
page_ext = lookup_page_ext(page);
345+
if (unlikely(!page_ext))
346+
continue;
320347

321348
/* Maybe overraping zone */
322349
if (test_bit(PAGE_EXT_OWNER, &page_ext->flags))

‎mm/page_poison.c‎

Lines changed: 7 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -54,6 +54,9 @@ static inline void set_page_poison(struct page *page)
5454
struct page_ext *page_ext;
5555

5656
page_ext = lookup_page_ext(page);
57+
if (unlikely(!page_ext))
58+
return;
59+
5760
__set_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags);
5861
}
5962

@@ -62,6 +65,9 @@ static inline void clear_page_poison(struct page *page)
6265
struct page_ext *page_ext;
6366

6467
page_ext = lookup_page_ext(page);
68+
if (unlikely(!page_ext))
69+
return;
70+
6571
__clear_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags);
6672
}
6773

@@ -70,7 +76,7 @@ bool page_is_poisoned(struct page *page)
7076
struct page_ext *page_ext;
7177

7278
page_ext = lookup_page_ext(page);
73-
if (!page_ext)
79+
if (unlikely(!page_ext))
7480
return false;
7581

7682
return test_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags);

‎mm/vmstat.c‎

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1061,6 +1061,8 @@ static void pagetypeinfo_showmixedcount_print(struct seq_file *m,
10611061
continue;
10621062

10631063
page_ext = lookup_page_ext(page);
1064+
if (unlikely(!page_ext))
1065+
continue;
10641066

10651067
if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags))
10661068
continue;

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