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
[akpm@linux-foundation.org: fix build-breaking typos]
[arnd@arndb.de: fix build problems from lookup_page_ext]
Link: http://lkml.kernel.org/r/6285269.2CksypHdYp@wuerfel
[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/1464023768-31025-1-git-send-email-yang.shi@linaro.org
Signed-off-by: Yang Shi <yang.shi@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/page_owner.c b/mm/page_owner.c
index 792b56d..c6cda3e 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -55,6 +55,8 @@
for (i = 0; i < (1 << order); i++) {
page_ext = lookup_page_ext(page + i);
+ if (unlikely(!page_ext))
+ continue;
__clear_bit(PAGE_EXT_OWNER, &page_ext->flags);
}
}
@@ -62,6 +64,7 @@
void __set_page_owner(struct page *page, unsigned int order, gfp_t gfp_mask)
{
struct page_ext *page_ext = lookup_page_ext(page);
+
struct stack_trace trace = {
.nr_entries = 0,
.max_entries = ARRAY_SIZE(page_ext->trace_entries),
@@ -69,6 +72,9 @@
.skip = 3,
};
+ if (unlikely(!page_ext))
+ return;
+
save_stack_trace(&trace);
page_ext->order = order;
@@ -82,6 +88,8 @@
void __set_page_owner_migrate_reason(struct page *page, int reason)
{
struct page_ext *page_ext = lookup_page_ext(page);
+ if (unlikely(!page_ext))
+ return;
page_ext->last_migrate_reason = reason;
}
@@ -89,6 +97,12 @@
gfp_t __get_page_owner_gfp(struct page *page)
{
struct page_ext *page_ext = lookup_page_ext(page);
+ if (unlikely(!page_ext))
+ /*
+ * The caller just returns 0 if no valid gfp
+ * So return 0 here too.
+ */
+ return 0;
return page_ext->gfp_mask;
}
@@ -99,6 +113,9 @@
struct page_ext *new_ext = lookup_page_ext(newpage);
int i;
+ if (unlikely(!old_ext || !new_ext))
+ return;
+
new_ext->order = old_ext->order;
new_ext->gfp_mask = old_ext->gfp_mask;
new_ext->nr_entries = old_ext->nr_entries;
@@ -193,6 +210,11 @@
gfp_t gfp_mask = page_ext->gfp_mask;
int mt = gfpflags_to_migratetype(gfp_mask);
+ if (unlikely(!page_ext)) {
+ pr_alert("There is not page extension available.\n");
+ return;
+ }
+
if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) {
pr_alert("page_owner info is not active (free page?)\n");
return;
@@ -251,6 +273,8 @@
}
page_ext = lookup_page_ext(page);
+ if (unlikely(!page_ext))
+ continue;
/*
* Some pages could be missed by concurrent allocation or free,
@@ -317,6 +341,8 @@
continue;
page_ext = lookup_page_ext(page);
+ if (unlikely(!page_ext))
+ continue;
/* Maybe overraping zone */
if (test_bit(PAGE_EXT_OWNER, &page_ext->flags))