This is a note to let you know that I've just added the patch titled
mm: check the return value of lookup_page_ext for all call sites
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-check-the-return-value-of-lookup_page_ext-for-all-call-sites.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From f86e4271978bd93db466d6a95dad4b0fdcdb04f6 Mon Sep 17 00:00:00 2001
From: Yang Shi <yang.shi@xxxxxxxxxx>
Date: Fri, 3 Jun 2016 14:55:38 -0700
Subject: mm: check the return value of lookup_page_ext for all call sites
From: Yang Shi <yang.shi@xxxxxxxxxx>
commit f86e4271978bd93db466d6a95dad4b0fdcdb04f6 upstream.
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@xxxxxxxxxxxxxxxxxxxx: fix build-breaking typos]
[arnd@xxxxxxxx: fix build problems from lookup_page_ext]
Link: http://lkml.kernel.org/r/6285269.2CksypHdYp@wuerfel
[akpm@xxxxxxxxxxxxxxxxxxxx: coding-style fixes]
Link: http://lkml.kernel.org/r/1464023768-31025-1-git-send-email-yang.shi@xxxxxxxxxx
Signed-off-by: Yang Shi <yang.shi@xxxxxxxxxx>
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/linux/page_idle.h | 43 ++++++++++++++++++++++++++++++++++++-------
mm/debug-pagealloc.c | 6 ++++++
mm/page_alloc.c | 6 ++++++
mm/page_owner.c | 16 ++++++++++++++++
mm/vmstat.c | 2 ++
5 files changed, 66 insertions(+), 7 deletions(-)
--- a/include/linux/page_idle.h
+++ b/include/linux/page_idle.h
@@ -46,33 +46,62 @@ extern struct page_ext_operations page_i
static inline bool page_is_young(struct page *page)
{
- return test_bit(PAGE_EXT_YOUNG, &lookup_page_ext(page)->flags);
+ struct page_ext *page_ext = lookup_page_ext(page);
+
+ if (unlikely(!page_ext))
+ return false;
+
+ return test_bit(PAGE_EXT_YOUNG, &page_ext->flags);
}
static inline void set_page_young(struct page *page)
{
- set_bit(PAGE_EXT_YOUNG, &lookup_page_ext(page)->flags);
+ struct page_ext *page_ext = lookup_page_ext(page);
+
+ if (unlikely(!page_ext))
+ return;
+
+ set_bit(PAGE_EXT_YOUNG, &page_ext->flags);
}
static inline bool test_and_clear_page_young(struct page *page)
{
- return test_and_clear_bit(PAGE_EXT_YOUNG,
- &lookup_page_ext(page)->flags);
+ struct page_ext *page_ext = lookup_page_ext(page);
+
+ if (unlikely(!page_ext))
+ return false;
+
+ return test_and_clear_bit(PAGE_EXT_YOUNG, &page_ext->flags);
}
static inline bool page_is_idle(struct page *page)
{
- return test_bit(PAGE_EXT_IDLE, &lookup_page_ext(page)->flags);
+ struct page_ext *page_ext = lookup_page_ext(page);
+
+ if (unlikely(!page_ext))
+ return false;
+
+ return test_bit(PAGE_EXT_IDLE, &page_ext->flags);
}
static inline void set_page_idle(struct page *page)
{
- set_bit(PAGE_EXT_IDLE, &lookup_page_ext(page)->flags);
+ struct page_ext *page_ext = lookup_page_ext(page);
+
+ if (unlikely(!page_ext))
+ return;
+
+ set_bit(PAGE_EXT_IDLE, &page_ext->flags);
}
static inline void clear_page_idle(struct page *page)
{
- clear_bit(PAGE_EXT_IDLE, &lookup_page_ext(page)->flags);
+ struct page_ext *page_ext = lookup_page_ext(page);
+
+ if (unlikely(!page_ext))
+ return;
+
+ clear_bit(PAGE_EXT_IDLE, &page_ext->flags);
}
#endif /* CONFIG_64BIT */
--- a/mm/debug-pagealloc.c
+++ b/mm/debug-pagealloc.c
@@ -34,6 +34,8 @@ static inline void set_page_poison(struc
struct page_ext *page_ext;
page_ext = lookup_page_ext(page);
+ if (page_ext)
+ return;
__set_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags);
}
@@ -42,6 +44,8 @@ static inline void clear_page_poison(str
struct page_ext *page_ext;
page_ext = lookup_page_ext(page);
+ if (page_ext)
+ return;
__clear_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags);
}
@@ -50,6 +54,8 @@ static inline bool page_poison(struct pa
struct page_ext *page_ext;
page_ext = lookup_page_ext(page);
+ if (page_ext)
+ return false;
return test_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags);
}
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -569,6 +569,9 @@ static inline void set_page_guard(struct
return;
page_ext = lookup_page_ext(page);
+ if (unlikely(!page_ext))
+ return;
+
__set_bit(PAGE_EXT_DEBUG_GUARD, &page_ext->flags);
INIT_LIST_HEAD(&page->lru);
@@ -586,6 +589,9 @@ static inline void clear_page_guard(stru
return;
page_ext = lookup_page_ext(page);
+ if (unlikely(!page_ext))
+ return;
+
__clear_bit(PAGE_EXT_DEBUG_GUARD, &page_ext->flags);
set_page_private(page, 0);
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -53,6 +53,8 @@ void __reset_page_owner(struct page *pag
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);
}
}
@@ -60,6 +62,7 @@ void __reset_page_owner(struct page *pag
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),
@@ -67,6 +70,9 @@ void __set_page_owner(struct page *page,
.skip = 3,
};
+ if (unlikely(!page_ext))
+ return;
+
save_stack_trace(&trace);
page_ext->order = order;
@@ -79,6 +85,12 @@ void __set_page_owner(struct page *page,
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;
}
@@ -194,6 +206,8 @@ read_page_owner(struct file *file, char
}
page_ext = lookup_page_ext(page);
+ if (unlikely(!page_ext))
+ continue;
/*
* Some pages could be missed by concurrent allocation or free,
@@ -257,6 +271,8 @@ static void init_pages_in_zone(pg_data_t
continue;
page_ext = lookup_page_ext(page);
+ if (unlikely(!page_ext))
+ continue;
/* Maybe overraping zone */
if (test_bit(PAGE_EXT_OWNER, &page_ext->flags))
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1091,6 +1091,8 @@ static void pagetypeinfo_showmixedcount_
continue;
page_ext = lookup_page_ext(page);
+ if (unlikely(!page_ext))
+ continue;
if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags))
continue;
Patches currently in stable-queue which might be from yang.shi@xxxxxxxxxx are
queue-4.4/mm-check-the-return-value-of-lookup_page_ext-for-all-call-sites.patch